test: align test mode with ACK/time flow and expose ack metrics

- Compute ACK receive window from airtime with bounds and margin
- Retry once if initial window misses
- Document ACK window sizing

README.md

@@ -1,347 +1,129 @@
-# DD3 LoRa Bridge (Multi-Sender)
+# DD3-LoRa-Bridge-MultiSender
 
-Unified firmware for LilyGO T3 v1.6.1 (ESP32 + SX1276 + SSD1306) that runs as **Sender** or **Receiver** based on a GPIO jumper. Senders read DD3 smart meter values, compress JSON, and transmit over LoRa. The receiver validates packets, publishes to MQTT, provides a web UI, and shows per-sender status on the OLED.
+Firmware for LilyGO T3 v1.6.1 (`ESP32 + SX1276 + SSD1306`) that runs as either:
+- `Sender` (PIN `GPIO14` HIGH): reads multiple IEC 62056-21 meters, batches data, sends over LoRa.
+- `Receiver` (PIN `GPIO14` LOW): receives/ACKs batches, publishes MQTT, serves web UI, logs to SD.
 
-## Hardware
+## Current Architecture
-Board: **LilyGO T3 LoRa32 v1.6.1** (ESP32 + SX1276 + SSD1306 128x64 + LiPo)
-Variants:
-- SX1276 **433 MHz** module (default build)
-- SX1276 **868 MHz** module (use 868 build environments)
 
-### Pin Mapping
+- Single codebase, role selected at boot via `detect_role()` (`include/config.h`, `src/config.cpp`).
-- LoRa (SX1276)
+- LoRa link uses explicit CRC16 frame protection in firmware (`src/lora_transport.cpp`), in addition to LoRa PHY CRC.
-  - SCK: GPIO5
+- Sender batches up to `30` samples and retransmits on missing ACK (`BATCH_MAX_RETRIES=2`, policy `Keep`).
-  - MISO: GPIO19
+- Receiver handles AP fallback when STA config is missing/invalid and exposes a config/status web UI.
-  - MOSI: GPIO27
-  - NSS/CS: GPIO18
-  - RST: GPIO23
-  - DIO0: GPIO26
-- OLED (SSD1306)
-  - SDA: GPIO21
-  - SCL: GPIO22
-  - RST: **not used** (SSD1306 init uses `-1` reset pin)
-  - I2C address: 0x3C
-- I2C RTC (DS3231)
-  - SDA: GPIO21
-  - SCL: GPIO22
-  - I2C address: 0x68
-- Battery ADC: GPIO35 (via on-board divider)
-- **Role select**: GPIO13 (INPUT_PULLDOWN)
-  - LOW = Sender
-  - HIGH = Receiver
-- **OLED control**: GPIO14 (INPUT_PULLDOWN)
-  - HIGH = force OLED on
-  - LOW = allow auto-off after timeout
-- Smart meter UART RX: GPIO34 (input-only, always connected)
 
-### Notes on GPIOs
+## LoRa Frame Protocol (Current)
-- GPIO34/35/36/39 are input-only and have **no internal pullups/pulldowns**.
-- Strap pins (GPIO0/2/4/5/12/15) can affect boot; avoid for role or control jumpers.
 
-## Firmware Roles
+Frame format on-air:
-### Sender (battery-powered)
-- Reads smart meter via optical IR (UART 9600 7E1).
-- Extracts OBIS values:
-  - Energy total: 1-0:1.8.0*255
-  - Total power: 1-0:16.7.0*255
-  - Phase power: 36.7 / 56.7 / 76.7
-- Reads battery voltage and estimates SoC.
-- Builds JSON payload, compresses, wraps in LoRa packet, transmits.
-- Light sleeps between meter reads; batches are sent every 30s.
-- Listens for LoRa time sync packets to set UTC clock.
-- Uses DS3231 RTC after boot if no time sync has arrived yet.
-- OLED shows status + meter data pages.
 
-**Sender flow (pseudo-code)**:
+`[msg_kind:1][device_short_id:2][payload...][crc16:2]`
-```cpp
-void sender_loop() {
-  meter_read_every_second(); // OBIS -> MeterData samples
-  read_battery(data);        // VBAT + SoC
 
-  if (time_to_send_batch()) {
+`msg_kind`:
-    json = meterBatchToJson(samples, batch_id); // bat_v per batch, t_first/t_last included
+- `0` = `BatchUp`
-    compressed = compressBuffer(json);
+- `1` = `AckDown`
-    lora_send(packet(MeterBatch, compressed));
-  }
 
-  display_set_last_meter(data);
+### `BatchUp`
-  display_set_last_read(ok);
-  display_set_last_tx(ok);
-  display_tick();
 
-  lora_receive_time_sync(); // optional
+`BatchUp` is chunked in transport (`batch_id`, `chunk_index`, `chunk_count`, `total_len`) and then decoded via `payload_codec`.
-  light_sleep_until_next_event();
-}
-```
 
-**Key sender functions**:
+Payload header contains:
-```cpp
+- fixed magic/schema fields (`kMagic=0xDDB3`, `kSchema=2`)
-bool meter_read(MeterData &data);        // parse OBIS fields
+- `schema_id`
-void read_battery(MeterData &data);      // ADC -> volts + percent
+- sender/batch/time/error metadata
-bool meterDataToJson(const MeterData&, String&);
-bool compressBuffer(const uint8_t*, size_t, uint8_t*, size_t, size_t&);
-bool lora_send(const LoraPacket &pkt);   // add header + CRC16 and transmit
-```
 
-### Receiver (USB-powered)
+Supported payload schemas in this branch:
-- WiFi STA connect using stored config; if not available/fails, starts AP.
+- `schema_id=1` (`EnergyMulti`): integer kWh for up to 3 meters (`energy1_kwh`, `energy2_kwh`, `energy3_kwh`)
-- NTP sync (UTC) and local display in Europe/Berlin.
+- `schema_id=0` (legacy): older energy/power delta encoding path remains decode-compatible
-- Receives LoRa packets, verifies CRC16, decompresses, parses JSON.
-- Publishes meter JSON to MQTT.
-- Sends ACKs for MeterBatch packets and de-duplicates by batch_id.
-- Web UI:
-  - AP mode: status + WiFi/MQTT config.
-  - STA mode: status + per-sender pages.
-- OLED cycles through receiver status and per-sender pages (receiver OLED never sleeps).
 
-**Receiver loop (pseudo-code)**:
+`n == 0` is used as sync request (no meter samples).
-```cpp
-void receiver_loop() {
-  if (lora_receive(pkt)) {
-    if (pkt.type == MeterData) {
-      json = decompressBuffer(pkt.payload);
-      if (jsonToMeterData(json, data)) {
-        update_sender_status(data);
-        mqtt_publish_state(data);
-      }
-    } else if (pkt.type == MeterBatch) {
-      json = reassemble_and_decompress_batch(pkt);
-      for (sample in jsonToMeterBatch(json)) { // uses t_first/t_last for jittered timestamps
-        update_sender_status(sample);
-        mqtt_publish_state(sample);
-      }
-    }
-  }
 
-  if (time_to_send_timesync()) {
+### `AckDown` (7 bytes)
-    time_send_timesync(self_short_id); // 60s for first 10 min, then hourly if RTC is present
-  }
 
-  mqtt_loop();
+`[flags:1][batch_id_be:2][epoch_utc_be:4]`
-  web_server_loop();
-  display_set_receiver_status(...);
-  display_tick();
-}
-```
 
-**Key receiver functions**:
+- `flags bit0`: `time_valid`
-```cpp
+- Receiver sends ACK repeatedly (`ACK_REPEAT_COUNT=3`, `ACK_REPEAT_DELAY_MS=200`).
-bool lora_receive(LoraPacket &pkt, uint32_t timeout_ms);
+- Sender accepts time only if `time_valid=1` and `epoch >= MIN_ACCEPTED_EPOCH_UTC` (`2026-02-01 00:00:00 UTC`).
-bool jsonToMeterData(const String &json, MeterData &data);
-bool jsonToMeterBatch(const String &json, MeterData *samples, size_t max, size_t &count);
-bool mqtt_publish_state(const MeterData &data);
-void web_server_loop();                   // AP or STA UI
-void time_send_timesync(uint16_t self_id);
-```
 
-## Test Mode (compile-time)
+## Time Bootstrap Guardrail
-Enabled by `-DENABLE_TEST_MODE` (see `platformio.ini` test environment).
 
-- Sender: sends 4-digit test code every ~30s in JSON.
+On sender boot:
-- Receiver: shows last test code per sender and publishes to `/test` topic.
+- `g_time_acquired=false`
-- Normal behavior is excluded from test builds.
+- only sync requests every `SYNC_REQUEST_INTERVAL_MS` (15s)
+- no normal sampling/transmit until valid ACK time received
 
-**Test sender (pseudo-code)**:
+This prevents publishing/storing pre-threshold timestamps.
-```cpp
-void test_sender_loop() {
-  code = random_4_digits();
-  json = {id, role:"sender", test_code: code, ts};
-  lora_send(packet(TestCode, compress(json)));
-  display_set_test_code(code);
-}
-```
 
-**Test receiver (pseudo-code)**:
+## Multi-Meter Sender Behavior
-```cpp
-void test_receiver_loop() {
-  if (pkt.type == TestCode) {
-    json = decompress(pkt.payload);
-    update_sender_test_code(json);
-    mqtt_publish_test(id, json);
-  }
-}
-```
 
-## LoRa Protocol
+Implemented in `src/meter_driver.cpp` + sender path in `src/main.cpp`:
-Packet layout:
 
-```
+- Meter protocol: IEC 62056-21 ASCII, Mode D style framing (`/ ... !`)
-[0]    protocol_version (1)
+- UART settings: `9600 7E1`
-[1]    role (0=sender, 1=receiver)
+- Parsed OBIS: `1-0:1.8.0`
-[2..3] device_id_short (uint16)
+- Conversion: floor to integer kWh (`floorf`)
-[4]    payload_type (0=meter, 1=test, 2=time_sync, 3=meter_batch, 4=ack)
-[5..N-3] compressed payload
-[N-2..N-1] CRC16 (bytes 0..N-3)
-```
 
-LoRa radio settings:
+Meter count is build-dependent (`include/config.h`):
-- Frequency: **433 MHz** or **868 MHz** (set by build env via `LORA_FREQUENCY_HZ`)
+- Debug builds (`SERIAL_DEBUG_MODE=1`): `METER_COUNT=2`
-- SF10, BW 125 kHz, CR 4/5, CRC on, Sync Word 0x34
+- Prod builds (`SERIAL_DEBUG_MODE=0`): `METER_COUNT=3`
 
-## Data Format
+Default RX pins:
-JSON payload (sender + MQTT):
+- Meter1: `GPIO34` (`Serial2`)
+- Meter2: `GPIO25` (`Serial1`)
+- Meter3: `GPIO3` (`Serial`, prod only because debug serial is disabled)
 
-```json
+## Receiver Behavior
-{
-  "id": "F19C",
-  "ts": 1737200000,
-  "e_kwh": 1234.57,
-  "p_w": 950.00,
-  "p1_w": 500.00,
-  "p2_w": 450.00,
-  "p3_w": 0.00,
-  "bat_v": 3.92,
-  "bat_pct": 78
-}
-```
 
-MeterBatch JSON (compressed over LoRa) uses per-field arrays with integer units for easier ingestion:
+For valid `BatchUp` decode:
+1. Reassemble chunks and decode payload.
+2. Send `AckDown` immediately.
+3. Drop duplicate batches per sender (`batch_id` tracking).
+4. If `n==0`: treat as sync request only.
+5. Else convert to `MeterData`, log to SD, update web UI, publish MQTT.
 
-```json
+## MQTT Topics and Payloads
-{
-  "schema": 1,
-  "sender": "s01",
-  "batch_id": 1842,
-  "t0": 1738288000,
-  "t_first": 1738288000,
-  "t_last": 1738288030,
-  "dt_s": 1,
-  "n": 3,
-  "e_wh": [123456700, 123456701, 123456701],
-  "p_w": [930, 940, 950],
-  "p1_w": [480, 490, 500],
-  "p2_w": [450, 450, 450],
-  "p3_w": [0, 0, 0],
-  "bat_v": 3.92,
-  "meta": {
-    "rssi": -92,
-    "snr": 7.5,
-    "rx_ts": 1738288031
-  }
-}
-```
 
-Notes:
+State topic:
-- `sender` maps to `EXPECTED_SENDER_IDS` order (`s01` = first sender).
+- `smartmeter/<device_id>/state`
-- `meta` is injected by the receiver after batch reassembly.
-- `bat_v` is a single batch-level value (percent is calculated locally).
 
-## Device IDs
+Fault topic (retained):
-- Derived from WiFi STA MAC.
+- `smartmeter/<device_id>/faults`
-- `short_id = (MAC[4] << 8) | MAC[5]`
-- `device_id = dd3-%04X`
-- JSON `id` uses only the last 4 hex digits (e.g., `F19C`) to save airtime.
 
-Receiver expects known senders in `include/config.h` via:
+For `EnergyMulti` samples, state JSON includes:
-```cpp
+- `id`, `ts`
-constexpr uint8_t NUM_SENDERS = 1;
+- `energy1_kwh`, `energy2_kwh`, optional `energy3_kwh`
-inline constexpr uint16_t EXPECTED_SENDER_IDS[NUM_SENDERS] = { 0xF19C };
+- `bat_v`, `bat_pct`
-```
+- optional link fields: `rssi`, `snr`
+- fault/reject fields: `err_last`, `rx_reject`, `rx_reject_text` (+ non-zero counters)
 
-## OLED Behavior
+Home Assistant discovery publishing is enabled (`ENABLE_HA_DISCOVERY=true`) but still advertises legacy keys (`e_kwh`, `p_w`, `p1_w`, `p2_w`, `p3_w`) in `src/mqtt_client.cpp`.
-- Sender: OLED stays **ON for 10 seconds** on each wake, then powers down for sleep.
-- Receiver: OLED is always on (no auto-off).
-- Pages rotate every 4s.
 
-## Power & Battery
+## Web UI, Wi-Fi, Storage
-- Sender disables WiFi/BLE, reads VBAT via ADC, uses linear SoC map:
-  - 3.0 V = 0%
-  - 4.2 V = 100%
-- Uses deep sleep between cycles (`SENDER_WAKE_INTERVAL_SEC`).
 
-## Web UI
+- STA config is stored in Preferences (`wifi_manager`).
-- AP SSID: `DD3-Bridge-<short_id>`
+- If STA/MQTT config is unavailable, receiver starts AP mode with SSID prefix `DD3-Bridge-`.
-- AP password: `changeme123`
+- Web auth defaults are `admin/admin` (`WEB_AUTH_DEFAULT_USER/PASS`).
-- Endpoints:
+- SD logging is enabled (`ENABLE_SD_LOGGING=true`).
-  - `/`: status overview
-  - `/wifi`: WiFi/MQTT/NTP config (AP and STA)
-  - `/sender/<device_id>`: per-sender details
-
-## MQTT
-- Topic: `smartmeter/<deviceId>/state`
-- QoS 0
-- Test mode: `smartmeter/<deviceId>/test`
-- Client ID: `dd3-bridge-<device_id>` (stable, derived from MAC)
-
-## NTP
-- NTP servers are configurable in the web UI (`/wifi`).
-- Defaults: `pool.ntp.org` and `time.nist.gov`.
-## RTC (DS3231)
-- Optional DS3231 on the I2C bus. Connect SDA to GPIO21 and SCL to GPIO22 (same bus as the OLED).
-- Enable/disable with `ENABLE_DS3231` in `include/config.h`.
-- Receiver time sync packets set the RTC.
-- On boot, if no LoRa time sync has arrived yet, the sender uses the RTC time as the initial `ts_utc`.
-- When no RTC is present or enabled, the receiver keeps sending time sync every 60 seconds.
 
 ## Build Environments
-- `lilygo-t3-v1-6-1`: production build
-- `lilygo-t3-v1-6-1-test`: test build with `ENABLE_TEST_MODE`
-- `lilygo-t3-v1-6-1-868`: production build for 868 MHz modules
-- `lilygo-t3-v1-6-1-868-test`: test build for 868 MHz modules
 
-## Config Knobs
+From `platformio.ini`:
-Key timing settings in `include/config.h`:
-- `METER_SAMPLE_INTERVAL_MS`
-- `METER_SEND_INTERVAL_MS`
-- `BATCH_ACK_TIMEOUT_MS`
-- `BATCH_MAX_RETRIES`
- - `BATCH_QUEUE_DEPTH`
- - `BATCH_RETRY_POLICY` (keep or drop on retry exhaustion)
- - `SERIAL_DEBUG_MODE` / `SERIAL_DEBUG_DUMP_JSON`
- - `LORA_SEND_BYPASS` (debug only)
 
-## Limits & Known Constraints
+- `lilygo-t3-v1-6-1`
-- **Compression**: uses lightweight RLE (good for JSON but not optimal).
+- `lilygo-t3-v1-6-1-test`
-- **OBIS parsing**: supports IEC 62056-21 ASCII (Mode D); may need tuning for some meters.
+- `lilygo-t3-v1-6-1-868`
-- **Payload size**: single JSON frames < 256 bytes (ArduinoJson static doc); batch frames are chunked and reassembled.
+- `lilygo-t3-v1-6-1-868-test`
-- **Battery ADC**: uses simple linear calibration constant in `power_manager.cpp`.
+- `lilygo-t3-v1-6-1-payload-test`
-- **OLED**: no hardware reset line is used (matches working reference).
+- `lilygo-t3-v1-6-1-868-payload-test`
-- **Batch ACKs**: sender waits for ACK after a batch and retries up to `BATCH_MAX_RETRIES` with `BATCH_ACK_TIMEOUT_MS` between attempts.
+- `lilygo-t3-v1-6-1-prod`
+- `lilygo-t3-v1-6-1-868-prod`
 
-## Files & Modules
+Example:
-- `include/config.h`, `src/config.cpp`: pins, radio settings, sender IDs
-- `include/data_model.h`, `src/data_model.cpp`: MeterData + ID init
-- `include/json_codec.h`, `src/json_codec.cpp`: JSON encode/decode
-- `include/compressor.h`, `src/compressor.cpp`: RLE compression
-- `include/lora_transport.h`, `src/lora_transport.cpp`: LoRa packet + CRC
-- `include/meter_driver.h`, `src/meter_driver.cpp`: IEC 62056-21 ASCII parse
-- `include/power_manager.h`, `src/power_manager.cpp`: ADC + sleep
-- `include/time_manager.h`, `src/time_manager.cpp`: NTP + time sync
-- `include/wifi_manager.h`, `src/wifi_manager.cpp`: NVS config + WiFi
-- `include/mqtt_client.h`, `src/mqtt_client.cpp`: MQTT publish
-- `include/web_server.h`, `src/web_server.cpp`: AP/STA web pages
-- `include/display_ui.h`, `src/display_ui.cpp`: OLED pages + control
-- `include/test_mode.h`, `src/test_mode.cpp`: test sender/receiver
-- `src/main.cpp`: role detection and main loop
-
-## Quick Start
-1. Set role jumper on GPIO13:
-   - LOW: sender
-   - HIGH: receiver
-2. OLED control on GPIO14:
-   - HIGH: always on
-   - LOW: auto-off after 10 minutes
-3. Build and upload:
 
 ```bash
-pio run -e lilygo-t3-v1-6-1 -t upload --upload-port COMx
+~/.platformio/penv/bin/pio run -e lilygo-t3-v1-6-1
 ```
 
-Test mode:
+## Test Mode
-
-```bash
-pio run -e lilygo-t3-v1-6-1-test -t upload --upload-port COMx
-```
-
-868 MHz builds:
-
-```bash
-pio run -e lilygo-t3-v1-6-1-868 -t upload --upload-port COMx
-```
-
-868 MHz test mode:
-
-```bash
-pio run -e lilygo-t3-v1-6-1-868-test -t upload --upload-port COMx
-```
 
+`ENABLE_TEST_MODE` replaces normal sender/receiver loops with dedicated test loops (`src/test_mode.cpp`).
+It sends/receives plain JSON test frames and publishes to `smartmeter/<device_id>/test`.

include/compressor.h

@@ -1,6 +0,0 @@
-#pragma once
-
-#include <Arduino.h>
-
-bool compressBuffer(const uint8_t *in, size_t in_len, uint8_t *out, size_t out_max, size_t &out_len);
-bool decompressBuffer(const uint8_t *in, size_t in_len, uint8_t *out, size_t out_max, size_t &out_len);

include/config.h

@@ -7,21 +7,11 @@ enum class DeviceRole : uint8_t {
   Receiver = 1
 };
 
-enum class PayloadType : uint8_t {
-  MeterData = 0,
-  TestCode = 1,
-  TimeSync = 2,
-  MeterBatch = 3,
-  Ack = 4
-};
-
 enum class BatchRetryPolicy : uint8_t {
   Keep = 0,
   Drop = 1
 };
 
-constexpr uint8_t PROTOCOL_VERSION = 1;
-
 // Pin definitions
 constexpr uint8_t PIN_LORA_SCK = 5;
 constexpr uint8_t PIN_LORA_MISO = 19;
@@ -39,17 +29,19 @@ constexpr uint8_t OLED_HEIGHT = 64;
 
 constexpr uint8_t PIN_BAT_ADC = 35;
 
-constexpr uint8_t PIN_ROLE = 13;
+constexpr uint8_t PIN_ROLE = 14;
-constexpr uint8_t PIN_OLED_CTRL = 14;
+constexpr uint8_t PIN_OLED_CTRL = 13;
 
-constexpr uint8_t PIN_METER_RX = 34;
+constexpr uint8_t PIN_METER1_RX = 34; // UART2 RX
+constexpr uint8_t PIN_METER2_RX = 25; // UART1 RX
+constexpr uint8_t PIN_METER3_RX = 3;  // UART0 RX (prod only, when serial debug is off)
 
 // LoRa settings
 #ifndef LORA_FREQUENCY_HZ
 #define LORA_FREQUENCY_HZ 433E6
 #endif
 constexpr long LORA_FREQUENCY = LORA_FREQUENCY_HZ;
-constexpr uint8_t LORA_SPREADING_FACTOR = 10;
+constexpr uint8_t LORA_SPREADING_FACTOR = 12;
 constexpr long LORA_BANDWIDTH = 125E3;
 constexpr uint8_t LORA_CODING_RATE = 5;
 constexpr uint8_t LORA_SYNC_WORD = 0x34;
@@ -57,27 +49,50 @@ constexpr uint8_t LORA_PREAMBLE_LEN = 8;
 
 // Timing
 constexpr uint32_t SENDER_WAKE_INTERVAL_SEC = 30;
-constexpr uint32_t TIME_SYNC_INTERVAL_SEC = 60;
+constexpr uint32_t SYNC_REQUEST_INTERVAL_MS = 15000;
-constexpr uint32_t TIME_SYNC_SLOW_INTERVAL_SEC = 3600;
-constexpr uint32_t TIME_SYNC_FAST_WINDOW_MS = 10UL * 60UL * 1000UL;
-constexpr bool ENABLE_DS3231 = true;
 constexpr uint32_t OLED_PAGE_INTERVAL_MS = 4000;
 constexpr uint32_t OLED_AUTO_OFF_MS = 10UL * 60UL * 1000UL;
 constexpr uint32_t SENDER_OLED_READ_MS = 10000;
 constexpr uint32_t METER_SAMPLE_INTERVAL_MS = 1000;
 constexpr uint32_t METER_SEND_INTERVAL_MS = 30000;
+constexpr uint32_t BATTERY_SAMPLE_INTERVAL_MS = 60000;
+constexpr float BATTERY_CAL = 1.083f;
 constexpr uint32_t BATCH_ACK_TIMEOUT_MS = 3000;
+constexpr uint8_t ACK_REPEAT_COUNT = 3;
+constexpr uint32_t ACK_REPEAT_DELAY_MS = 200;
 constexpr uint8_t BATCH_MAX_RETRIES = 2;
 constexpr uint8_t METER_BATCH_MAX_SAMPLES = 30;
 constexpr uint8_t BATCH_QUEUE_DEPTH = 10;
 constexpr BatchRetryPolicy BATCH_RETRY_POLICY = BatchRetryPolicy::Keep;
 constexpr uint32_t WATCHDOG_TIMEOUT_SEC = 120;
 constexpr bool ENABLE_HA_DISCOVERY = true;
-constexpr bool SERIAL_DEBUG_MODE = false;
+#ifndef SERIAL_DEBUG_MODE_FLAG
+#define SERIAL_DEBUG_MODE_FLAG 0
+#endif
+constexpr bool SERIAL_DEBUG_MODE = SERIAL_DEBUG_MODE_FLAG != 0;
+constexpr uint8_t METER_COUNT_DEBUG = 2;
+constexpr uint8_t METER_COUNT_PROD = 3;
+constexpr uint8_t METER_COUNT = SERIAL_DEBUG_MODE ? METER_COUNT_DEBUG : METER_COUNT_PROD;
 constexpr bool SERIAL_DEBUG_DUMP_JSON = false;
 constexpr bool LORA_SEND_BYPASS = false;
+constexpr bool ENABLE_SD_LOGGING = true;
+constexpr uint8_t PIN_SD_CS = 13;
+constexpr uint8_t PIN_SD_MOSI = 15;
+constexpr uint8_t PIN_SD_MISO = 2;
+constexpr uint8_t PIN_SD_SCK = 14;
+constexpr uint16_t SD_HISTORY_MAX_DAYS = 30;
+constexpr uint16_t SD_HISTORY_MIN_RES_MIN = 1;
+constexpr uint16_t SD_HISTORY_MAX_BINS = 4000;
+constexpr uint16_t SD_HISTORY_TIME_BUDGET_MS = 10;
+constexpr const char *AP_SSID_PREFIX = "DD3-Bridge-";
+constexpr const char *AP_PASSWORD = "changeme123";
+constexpr bool WEB_AUTH_REQUIRE_STA = true;
+constexpr bool WEB_AUTH_REQUIRE_AP = false;
+constexpr const char *WEB_AUTH_DEFAULT_USER = "admin";
+constexpr const char *WEB_AUTH_DEFAULT_PASS = "admin";
 
 constexpr uint8_t NUM_SENDERS = 1;
+constexpr uint32_t MIN_ACCEPTED_EPOCH_UTC = 1769904000UL; // 2026-02-01 00:00:00 UTC
 inline constexpr uint16_t EXPECTED_SENDER_IDS[NUM_SENDERS] = {
   0xF19C //433mhz sender
   //0x7EB4 //868mhz sender

include/data_model.h

@@ -9,6 +9,15 @@ enum class FaultType : uint8_t {
   LoraTx = 3
 };
 
+enum class RxRejectReason : uint8_t {
+  None = 0,
+  CrcFail = 1,
+  InvalidMsgKind = 2,
+  LengthMismatch = 3,
+  DeviceIdMismatch = 4,
+  BatchIdMismatch = 5
+};
+
 struct FaultCounters {
   uint32_t meter_read_fail;
   uint32_t decode_fail;
@@ -19,6 +28,9 @@ struct MeterData {
   uint32_t ts_utc;
   uint16_t short_id;
   char device_id[16];
+  bool energy_multi;
+  uint8_t energy_meter_count;
+  uint32_t energy_kwh_int[3];
   float energy_total_kwh;
   float phase_power_w[3];
   float total_power_w;
@@ -32,12 +44,15 @@ struct MeterData {
   uint32_t err_decode;
   uint32_t err_lora_tx;
   FaultType last_error;
+  uint8_t rx_reject_reason;
 };
 
 struct SenderStatus {
   MeterData last_data;
   uint32_t last_update_ts_utc;
+  uint16_t last_acked_batch_id;
   bool has_data;
 };
 
 void init_device_ids(uint16_t &short_id, char *device_id, size_t device_id_len);
+const char *rx_reject_reason_text(RxRejectReason reason);

include/html_util.h

@@ -0,0 +1,7 @@
+#pragma once
+
+#include <Arduino.h>
+
+String html_escape(const String &input);
+String url_encode_component(const String &input);
+bool sanitize_device_id(const String &input, String &out_device_id);

include/json_codec.h

@@ -4,7 +4,3 @@
 #include "data_model.h"
 
 bool meterDataToJson(const MeterData &data, String &out_json);
-bool jsonToMeterData(const String &json, MeterData &data);
-bool meterBatchToJson(const MeterData *samples, size_t count, uint16_t batch_id, String &out_json,
-                      const FaultCounters *faults = nullptr, FaultType last_error = FaultType::None);
-bool jsonToMeterBatch(const String &json, MeterData *out_samples, size_t max_count, size_t &out_count);

include/lora_transport.h

@@ -2,14 +2,26 @@
 
 #include <Arduino.h>
 #include "config.h"
+#include "data_model.h"
 
 constexpr size_t LORA_MAX_PAYLOAD = 230;
+constexpr size_t LORA_FRAME_HEADER_LEN = 3; // msg_kind + dev_id_short
+constexpr size_t LORA_FRAME_CRC_LEN = 2;
+constexpr size_t LORA_ACK_DOWN_PAYLOAD_LEN = 7; // flags(1) + batch_id(2) + epoch_utc(4)
+static_assert(LORA_ACK_DOWN_PAYLOAD_LEN == 7, "ACK_DOWN payload must remain 7 bytes");
+
+constexpr size_t lora_frame_size(size_t payload_len) {
+  return LORA_FRAME_HEADER_LEN + payload_len + LORA_FRAME_CRC_LEN;
+}
+
+enum class LoraMsgKind : uint8_t {
+  BatchUp = 0,
+  AckDown = 1
+};
 
 struct LoraPacket {
-  uint8_t protocol_version;
+  LoraMsgKind msg_kind;
-  DeviceRole role;
   uint16_t device_id_short;
-  PayloadType payload_type;
   uint8_t payload[LORA_MAX_PAYLOAD];
   size_t payload_len;
   int16_t rssi_dbm;
@@ -19,5 +31,10 @@ struct LoraPacket {
 void lora_init();
 bool lora_send(const LoraPacket &pkt);
 bool lora_receive(LoraPacket &pkt, uint32_t timeout_ms);
+RxRejectReason lora_get_last_rx_reject_reason();
+bool lora_get_last_rx_signal(int16_t &rssi_dbm, float &snr_db);
+void lora_idle();
 void lora_sleep();
+void lora_receive_continuous();
+bool lora_receive_window(LoraPacket &pkt, uint32_t timeout_ms);
 uint32_t lora_airtime_ms(size_t packet_len);

include/meter_driver.h

@@ -1,7 +1,8 @@
 #pragma once
 
 #include <Arduino.h>
-#include "data_model.h"
 
 void meter_init();
-bool meter_read(MeterData &data);
+void meter_poll();
+uint8_t meter_count();
+bool meter_get_last_energy_kwh(uint8_t meter_idx, uint32_t &out_energy_kwh);

include/power_manager.h

@@ -5,6 +5,7 @@
 
 void power_sender_init();
 void power_receiver_init();
+void power_configure_unused_pins_sender();
 void read_battery(MeterData &data);
 uint8_t battery_percent_from_voltage(float voltage_v);
 void light_sleep_ms(uint32_t ms);

include/rtc_ds3231.h

@@ -1,8 +0,0 @@
-#pragma once
-
-#include <Arduino.h>
-
-bool rtc_ds3231_init();
-bool rtc_ds3231_is_present();
-bool rtc_ds3231_read_epoch(uint32_t &epoch_utc);
-bool rtc_ds3231_set_epoch(uint32_t epoch_utc);

include/time_manager.h

@@ -1,17 +1,11 @@
 #pragma once
 
 #include <Arduino.h>
-#include "lora_transport.h"
 
 void time_receiver_init(const char *ntp_server_1, const char *ntp_server_2);
 uint32_t time_get_utc();
 bool time_is_synced();
 void time_set_utc(uint32_t epoch);
-bool time_send_timesync(uint16_t device_id_short);
-bool time_handle_timesync_payload(const uint8_t *payload, size_t len);
 void time_get_local_hhmm(char *out, size_t out_len);
-void time_rtc_init();
-bool time_try_load_from_rtc();
-bool time_rtc_present();
 uint32_t time_get_last_sync_utc();
 uint32_t time_get_last_sync_age_sec();

include/wifi_manager.h

@@ -12,6 +12,8 @@ struct WifiMqttConfig {
   String mqtt_pass;
   String ntp_server_1;
   String ntp_server_2;
+  String web_user;
+  String web_pass;
   bool valid;
 };
 

platformio.ini

@@ -18,6 +18,8 @@ lib_deps =
   adafruit/Adafruit SSD1306@^2.5.9
   adafruit/Adafruit GFX Library@^1.11.9
   knolleary/PubSubClient@^2.8
+build_flags =
+  -DSERIAL_DEBUG_MODE_FLAG=1
 
 [env:lilygo-t3-v1-6-1-test]
 platform = https://github.com/pioarduino/platform-espressif32/releases/download/51.03.07/platform-espressif32.zip
@@ -30,6 +32,7 @@ lib_deps =
   adafruit/Adafruit GFX Library@^1.11.9
   knolleary/PubSubClient@^2.8
 build_flags =
+  -DSERIAL_DEBUG_MODE_FLAG=1
   -DENABLE_TEST_MODE
 
 [env:lilygo-t3-v1-6-1-868]
@@ -43,6 +46,7 @@ lib_deps =
   adafruit/Adafruit GFX Library@^1.11.9
   knolleary/PubSubClient@^2.8
 build_flags =
+  -DSERIAL_DEBUG_MODE_FLAG=1
   -DLORA_FREQUENCY_HZ=868E6
 
 [env:lilygo-t3-v1-6-1-868-test]
@@ -56,5 +60,62 @@ lib_deps =
   adafruit/Adafruit GFX Library@^1.11.9
   knolleary/PubSubClient@^2.8
 build_flags =
+  -DSERIAL_DEBUG_MODE_FLAG=1
   -DENABLE_TEST_MODE
   -DLORA_FREQUENCY_HZ=868E6
+
+[env:lilygo-t3-v1-6-1-payload-test]
+platform = https://github.com/pioarduino/platform-espressif32/releases/download/51.03.07/platform-espressif32.zip
+board = ttgo-lora32-v1
+framework = arduino
+lib_deps =
+  sandeepmistry/LoRa@^0.8.0
+  bblanchon/ArduinoJson@^6.21.5
+  adafruit/Adafruit SSD1306@^2.5.9
+  adafruit/Adafruit GFX Library@^1.11.9
+  knolleary/PubSubClient@^2.8
+build_flags =
+  -DSERIAL_DEBUG_MODE_FLAG=1
+  -DPAYLOAD_CODEC_TEST
+
+[env:lilygo-t3-v1-6-1-868-payload-test]
+platform = https://github.com/pioarduino/platform-espressif32/releases/download/51.03.07/platform-espressif32.zip
+board = ttgo-lora32-v1
+framework = arduino
+lib_deps =
+  sandeepmistry/LoRa@^0.8.0
+  bblanchon/ArduinoJson@^6.21.5
+  adafruit/Adafruit SSD1306@^2.5.9
+  adafruit/Adafruit GFX Library@^1.11.9
+  knolleary/PubSubClient@^2.8
+build_flags =
+  -DSERIAL_DEBUG_MODE_FLAG=1
+  -DPAYLOAD_CODEC_TEST
+  -DLORA_FREQUENCY_HZ=868E6
+
+[env:lilygo-t3-v1-6-1-prod]
+platform = https://github.com/pioarduino/platform-espressif32/releases/download/51.03.07/platform-espressif32.zip
+board = ttgo-lora32-v1
+framework = arduino
+lib_deps =
+  sandeepmistry/LoRa@^0.8.0
+  bblanchon/ArduinoJson@^6.21.5
+  adafruit/Adafruit SSD1306@^2.5.9
+  adafruit/Adafruit GFX Library@^1.11.9
+  knolleary/PubSubClient@^2.8
+build_flags =
+  -DSERIAL_DEBUG_MODE_FLAG=0
+
+[env:lilygo-t3-v1-6-1-868-prod]
+platform = https://github.com/pioarduino/platform-espressif32/releases/download/51.03.07/platform-espressif32.zip
+board = ttgo-lora32-v1
+framework = arduino
+lib_deps =
+  sandeepmistry/LoRa@^0.8.0
+  bblanchon/ArduinoJson@^6.21.5
+  adafruit/Adafruit SSD1306@^2.5.9
+  adafruit/Adafruit GFX Library@^1.11.9
+  knolleary/PubSubClient@^2.8
+build_flags =
+  -DSERIAL_DEBUG_MODE_FLAG=0
+  -DLORA_FREQUENCY_HZ=868E6

src/compressor.cpp

@@ -1,71 +0,0 @@
-#include "compressor.h"
-
-static constexpr uint8_t RLE_MARKER = 0xFF;
-
-bool compressBuffer(const uint8_t *in, size_t in_len, uint8_t *out, size_t out_max, size_t &out_len) {
-  out_len = 0;
-  if (!in || !out) {
-    return false;
-  }
-
-  size_t i = 0;
-  while (i < in_len) {
-    uint8_t value = in[i];
-    size_t run = 1;
-    while (i + run < in_len && in[i + run] == value && run < 255) {
-      run++;
-    }
-
-    if (value == RLE_MARKER || run >= 4) {
-      if (out_len + 3 > out_max) {
-        return false;
-      }
-      out[out_len++] = RLE_MARKER;
-      out[out_len++] = static_cast<uint8_t>(run);
-      out[out_len++] = value;
-    } else {
-      if (out_len + run > out_max) {
-        return false;
-      }
-      for (size_t j = 0; j < run; ++j) {
-        out[out_len++] = value;
-      }
-    }
-
-    i += run;
-  }
-
-  return true;
-}
-
-bool decompressBuffer(const uint8_t *in, size_t in_len, uint8_t *out, size_t out_max, size_t &out_len) {
-  out_len = 0;
-  if (!in || !out) {
-    return false;
-  }
-
-  size_t i = 0;
-  while (i < in_len) {
-    uint8_t value = in[i++];
-    if (value == RLE_MARKER) {
-      if (i + 1 >= in_len) {
-        return false;
-      }
-      uint8_t run = in[i++];
-      uint8_t data = in[i++];
-      if (out_len + run > out_max) {
-        return false;
-      }
-      for (uint8_t j = 0; j < run; ++j) {
-        out[out_len++] = data;
-      }
-    } else {
-      if (out_len + 1 > out_max) {
-        return false;
-      }
-      out[out_len++] = value;
-    }
-  }
-
-  return true;
-}

src/config.cpp

@@ -2,5 +2,5 @@
 
 DeviceRole detect_role() {
   pinMode(PIN_ROLE, INPUT_PULLDOWN);
-  return digitalRead(PIN_ROLE) == HIGH ? DeviceRole::Receiver : DeviceRole::Sender;
+  return digitalRead(PIN_ROLE) == HIGH ? DeviceRole::Sender : DeviceRole::Receiver;
 }

src/data_model.cpp

@@ -8,3 +8,20 @@ void init_device_ids(uint16_t &short_id, char *device_id, size_t device_id_len)
   short_id = (static_cast<uint16_t>(mac[4]) << 8) | mac[5];
   snprintf(device_id, device_id_len, "dd3-%04X", short_id);
 }
+
+const char *rx_reject_reason_text(RxRejectReason reason) {
+  switch (reason) {
+    case RxRejectReason::CrcFail:
+      return "crc_fail";
+    case RxRejectReason::InvalidMsgKind:
+      return "invalid_msg_kind";
+    case RxRejectReason::LengthMismatch:
+      return "length_mismatch";
+    case RxRejectReason::DeviceIdMismatch:
+      return "device_id_mismatch";
+    case RxRejectReason::BatchIdMismatch:
+      return "batch_id_mismatch";
+    default:
+      return "none";
+  }
+}

src/display_ui.cpp

@@ -4,6 +4,8 @@
 #include <Wire.h>
 #include <Adafruit_GFX.h>
 #include <Adafruit_SSD1306.h>
+#include <limits.h>
+#include <math.h>
 #include <time.h>
 
 static Adafruit_SSD1306 display(OLED_WIDTH, OLED_HEIGHT, &Wire, -1);
@@ -36,10 +38,9 @@ static bool g_mqtt_ok = false;
 
 static bool g_oled_on = true;
 static bool g_prev_ctrl_high = false;
-static uint32_t g_oled_off_start = 0;
 static uint32_t g_last_page_ms = 0;
 static uint8_t g_page = 0;
-static uint32_t g_boot_ms = 0;
+static uint32_t g_last_activity_ms = 0;
 static bool g_display_ready = false;
 static uint32_t g_last_init_attempt_ms = 0;
 static bool g_last_oled_on = true;
@@ -69,7 +70,9 @@ void display_power_down() {
 }
 
 void display_init() {
+  if (g_role == DeviceRole::Sender) {
     pinMode(PIN_OLED_CTRL, INPUT_PULLDOWN);
+  }
   Wire.begin(PIN_OLED_SDA, PIN_OLED_SCL);
   Wire.setClock(100000);
   g_display_ready = display.begin(SSD1306_SWITCHCAPVCC, OLED_I2C_ADDR);
@@ -81,7 +84,7 @@ void display_init() {
     display.display();
   }
   g_last_init_attempt_ms = millis();
-  g_boot_ms = millis();
+  g_last_activity_ms = millis();
 }
 
 void display_set_role(DeviceRole role) {
@@ -160,6 +163,20 @@ static uint32_t age_seconds(uint32_t ts_utc, uint32_t ts_ms) {
   return (millis() - ts_ms) / 1000;
 }
 
+static int32_t round_power_w(float value) {
+  if (isnan(value)) {
+    return 0;
+  }
+  long rounded = lroundf(value);
+  if (rounded > INT32_MAX) {
+    return INT32_MAX;
+  }
+  if (rounded < INT32_MIN) {
+    return INT32_MIN;
+  }
+  return static_cast<int32_t>(rounded);
+}
+
 static bool render_last_error_line(uint8_t y) {
   if (g_last_error == FaultType::None) {
     return false;
@@ -235,15 +252,15 @@ static void render_sender_status() {
 static void render_sender_measurement() {
   display.clearDisplay();
   display.setCursor(0, 0);
-  display.printf("E %.1f kWh", g_last_meter.energy_total_kwh);
+  display.printf("E %.2f kWh", g_last_meter.energy_total_kwh);
   display.setCursor(0, 12);
-  display.printf("P %.0fW", g_last_meter.total_power_w);
+  display.printf("P %dW", static_cast<int>(round_power_w(g_last_meter.total_power_w)));
   display.setCursor(0, 24);
-  display.printf("L1 %.0fW", g_last_meter.phase_power_w[0]);
+  display.printf("L1 %dW", static_cast<int>(round_power_w(g_last_meter.phase_power_w[0])));
   display.setCursor(0, 36);
-  display.printf("L2 %.0fW", g_last_meter.phase_power_w[1]);
+  display.printf("L2 %dW", static_cast<int>(round_power_w(g_last_meter.phase_power_w[1])));
   display.setCursor(0, 48);
-  display.printf("L3 %.0fW", g_last_meter.phase_power_w[2]);
+  display.printf("L3 %dW", static_cast<int>(round_power_w(g_last_meter.phase_power_w[2])));
   display.display();
 }
 
@@ -268,16 +285,10 @@ static void render_receiver_status() {
   display.printf("Time: %s", time_buf);
 
   uint32_t latest = 0;
-  bool link_valid = false;
-  int16_t link_rssi = 0;
-  float link_snr = 0.0f;
   if (g_statuses) {
     for (uint8_t i = 0; i < g_status_count; ++i) {
       if (g_statuses[i].has_data && g_statuses[i].last_update_ts_utc > latest) {
         latest = g_statuses[i].last_update_ts_utc;
-        link_valid = g_statuses[i].last_data.link_valid;
-        link_rssi = g_statuses[i].last_data.link_rssi_dbm;
-        link_snr = g_statuses[i].last_data.link_snr_db;
       }
     }
   }
@@ -291,9 +302,6 @@ static void render_receiver_status() {
     localtime_r(&t, &timeinfo);
     display.printf("Upd %02d:%02d", timeinfo.tm_hour, timeinfo.tm_min);
   }
-  if (link_valid) {
-    display.printf(" R:%d S:%.1f", link_rssi, link_snr);
-  }
 
   render_last_error_line(56);
   display.display();
@@ -342,15 +350,37 @@ static void render_receiver_sender(uint8_t index) {
 #endif
 
   display.setCursor(0, 12);
-  display.printf("E %.1f kWh", status.last_data.energy_total_kwh);
+  if (status.last_data.energy_multi) {
-  display.setCursor(0, 24);
+    display.printf("E1 %lu E2 %lu", static_cast<unsigned long>(status.last_data.energy_kwh_int[0]),
-  display.printf("P %.0fW", status.last_data.total_power_w);
+                   static_cast<unsigned long>(status.last_data.energy_kwh_int[1]));
-  display.setCursor(0, 36);
+  } else {
-  display.printf("L1 %.0fW", status.last_data.phase_power_w[0]);
+    display.printf("E %.2f kWh", status.last_data.energy_total_kwh);
-  display.setCursor(0, 48);
+  }
-  display.printf("L2 %.0fW", status.last_data.phase_power_w[1]);
+  display.setCursor(0, 22);
-  display.setCursor(0, 56);
+  if (status.last_data.energy_multi && status.last_data.energy_meter_count >= 3) {
-  display.printf("L3 %.0fW", status.last_data.phase_power_w[2]);
+    display.printf("E3 %lu", static_cast<unsigned long>(status.last_data.energy_kwh_int[2]));
+  } else {
+    display.printf("L1 %dW", static_cast<int>(round_power_w(status.last_data.phase_power_w[0])));
+  }
+  display.setCursor(0, 32);
+  display.printf("L2 %dW", static_cast<int>(round_power_w(status.last_data.phase_power_w[1])));
+  display.setCursor(0, 42);
+  display.printf("L3 %dW", static_cast<int>(round_power_w(status.last_data.phase_power_w[2])));
+  display.setCursor(0, 52);
+  display.print("P");
+  char p_buf[16];
+  snprintf(p_buf, sizeof(p_buf), "%dW", static_cast<int>(round_power_w(status.last_data.total_power_w)));
+  int16_t x1 = 0;
+  int16_t y1 = 0;
+  uint16_t w = 0;
+  uint16_t h = 0;
+  display.getTextBounds(p_buf, 0, 0, &x1, &y1, &w, &h);
+  int16_t x = static_cast<int16_t>(display.width() - w);
+  if (x < 0) {
+    x = 0;
+  }
+  display.setCursor(x, 52);
+  display.print(p_buf);
   display.display();
 }
 
@@ -369,29 +399,21 @@ void display_tick() {
     }
     return;
   }
-  bool ctrl_high = digitalRead(PIN_OLED_CTRL) == HIGH;
+  bool ctrl_high = false;
+  if (g_role == DeviceRole::Sender) {
+    ctrl_high = digitalRead(PIN_OLED_CTRL) == HIGH;
+  }
 
-  bool in_boot_window = (millis() - g_boot_ms) < OLED_AUTO_OFF_MS;
+  uint32_t now_ms = millis();
+  bool ctrl_falling_edge = g_prev_ctrl_high && !ctrl_high;
   if (g_role == DeviceRole::Receiver) {
     g_oled_on = true;
-    g_oled_off_start = 0;
+    g_last_activity_ms = now_ms;
-  } else if (in_boot_window) {
-    g_oled_on = true;
   } else {
-    if (ctrl_high) {
+    if (ctrl_high || ctrl_falling_edge) {
-      g_oled_on = true;
+      g_last_activity_ms = now_ms;
-      g_oled_off_start = 0;
-    } else if (g_prev_ctrl_high && !ctrl_high) {
-      g_oled_off_start = millis();
-    } else if (!g_prev_ctrl_high && !ctrl_high && g_oled_off_start == 0) {
-      g_oled_off_start = millis();
     }
-
+    g_oled_on = (now_ms - g_last_activity_ms) < OLED_AUTO_OFF_MS;
-    if (!ctrl_high && g_oled_off_start > 0 && millis() - g_oled_off_start > OLED_AUTO_OFF_MS) {
-      g_oled_on = false;
-    }
-
-    // fall through to power gating below
   }
 
   if (g_oled_on) {

src/html_util.cpp

@@ -0,0 +1,98 @@
+#include "html_util.h"
+
+String html_escape(const String &input) {
+  String out;
+  out.reserve(input.length() + 8);
+  for (size_t i = 0; i < input.length(); ++i) {
+    char c = input[i];
+    switch (c) {
+      case '&':
+        out += "&amp;";
+        break;
+      case '<':
+        out += "&lt;";
+        break;
+      case '>':
+        out += "&gt;";
+        break;
+      case '"':
+        out += "&quot;";
+        break;
+      case '\'':
+        out += "&#39;";
+        break;
+      default:
+        out += c;
+        break;
+    }
+  }
+  return out;
+}
+
+String url_encode_component(const String &input) {
+  String out;
+  out.reserve(input.length() * 3);
+  const char *hex = "0123456789ABCDEF";
+  for (size_t i = 0; i < input.length(); ++i) {
+    unsigned char c = static_cast<unsigned char>(input[i]);
+    bool safe = (c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z') ||
+        (c >= '0' && c <= '9') || c == '-' || c == '_' || c == '.' || c == '~';
+    if (safe) {
+      out += static_cast<char>(c);
+    } else {
+      out += '%';
+      out += hex[(c >> 4) & 0x0F];
+      out += hex[c & 0x0F];
+    }
+  }
+  return out;
+}
+
+static bool is_hex_char(char c) {
+  return (c >= '0' && c <= '9') ||
+      (c >= 'a' && c <= 'f') ||
+      (c >= 'A' && c <= 'F');
+}
+
+static String to_upper_hex4(const String &input) {
+  String out = input;
+  out.toUpperCase();
+  return out;
+}
+
+bool sanitize_device_id(const String &input, String &out_device_id) {
+  String trimmed = input;
+  trimmed.trim();
+  if (trimmed.length() == 0) {
+    return false;
+  }
+  if (trimmed.indexOf('/') >= 0 || trimmed.indexOf('\\') >= 0 || trimmed.indexOf("..") >= 0) {
+    return false;
+  }
+  if (trimmed.indexOf('%') >= 0) {
+    return false;
+  }
+
+  if (trimmed.length() == 4) {
+    for (size_t i = 0; i < 4; ++i) {
+      if (!is_hex_char(trimmed[i])) {
+        return false;
+      }
+    }
+    out_device_id = String("dd3-") + to_upper_hex4(trimmed);
+    return true;
+  }
+
+  if (trimmed.length() == 8 && trimmed.startsWith("dd3-")) {
+    String hex = trimmed.substring(4);
+    for (size_t i = 0; i < 4; ++i) {
+      if (!is_hex_char(hex[i])) {
+        return false;
+      }
+    }
+    out_device_id = String("dd3-") + to_upper_hex4(hex);
+    return true;
+  }
+
+  return false;
+}

src/json_codec.cpp

@@ -2,8 +2,6 @@
 #include <ArduinoJson.h>
 #include <limits.h>
 #include <math.h>
-#include "config.h"
-#include "power_manager.h"
 
 static float round2(float value) {
   if (isnan(value)) {
@@ -12,20 +10,6 @@ static float round2(float value) {
   return roundf(value * 100.0f) / 100.0f;
 }
 
-static uint32_t kwh_to_wh(float value) {
-  if (isnan(value)) {
-    return 0;
-  }
-  double wh = static_cast<double>(value) * 1000.0;
-  if (wh < 0.0) {
-    wh = 0.0;
-  }
-  if (wh > static_cast<double>(UINT32_MAX)) {
-    wh = static_cast<double>(UINT32_MAX);
-  }
-  return static_cast<uint32_t>(llround(wh));
-}
-
 static int32_t round_to_i32(float value) {
   if (isnan(value)) {
     return 0;
@@ -51,31 +35,6 @@ static const char *short_id_from_device_id(const char *device_id) {
   return device_id;
 }
 
-static void sender_label_from_short_id(uint16_t short_id, char *out, size_t out_len) {
-  if (!out || out_len == 0) {
-    return;
-  }
-  for (uint8_t i = 0; i < NUM_SENDERS; ++i) {
-    if (EXPECTED_SENDER_IDS[i] == short_id) {
-      snprintf(out, out_len, "s%02u", static_cast<unsigned>(i + 1));
-      return;
-    }
-  }
-  snprintf(out, out_len, "s00");
-}
-
-static uint16_t short_id_from_sender_label(const char *sender_label) {
-  if (!sender_label || strlen(sender_label) < 2 || sender_label[0] != 's') {
-    return 0;
-  }
-  char *end = nullptr;
-  long idx = strtol(sender_label + 1, &end, 10);
-  if (end == sender_label + 1 || idx <= 0 || idx > NUM_SENDERS) {
-    return 0;
-  }
-  return EXPECTED_SENDER_IDS[idx - 1];
-}
-
 static void format_float_2(char *buf, size_t buf_len, float value) {
   if (!buf || buf_len == 0) {
     return;
@@ -87,21 +46,36 @@ static void format_float_2(char *buf, size_t buf_len, float value) {
   snprintf(buf, buf_len, "%.2f", round2(value));
 }
 
+static void set_int_or_null(JsonDocument &doc, const char *key, float value) {
+  if (!key || key[0] == '\0') {
+    return;
+  }
+  if (isnan(value)) {
+    doc[key] = nullptr;
+    return;
+  }
+  doc[key] = round_to_i32(value);
+}
+
 bool meterDataToJson(const MeterData &data, String &out_json) {
-  StaticJsonDocument<256> doc;
+  StaticJsonDocument<320> doc;
   doc["id"] = short_id_from_device_id(data.device_id);
   doc["ts"] = data.ts_utc;
   char buf[16];
+  if (data.energy_multi) {
+    doc["energy1_kwh"] = data.energy_kwh_int[0];
+    doc["energy2_kwh"] = data.energy_kwh_int[1];
+    if (data.energy_meter_count >= 3) {
+      doc["energy3_kwh"] = data.energy_kwh_int[2];
+    }
+  } else {
     format_float_2(buf, sizeof(buf), data.energy_total_kwh);
     doc["e_kwh"] = serialized(buf);
-  format_float_2(buf, sizeof(buf), data.total_power_w);
+    set_int_or_null(doc, "p_w", data.total_power_w);
-  doc["p_w"] = serialized(buf);
+    set_int_or_null(doc, "p1_w", data.phase_power_w[0]);
-  format_float_2(buf, sizeof(buf), data.phase_power_w[0]);
+    set_int_or_null(doc, "p2_w", data.phase_power_w[1]);
-  doc["p1_w"] = serialized(buf);
+    set_int_or_null(doc, "p3_w", data.phase_power_w[2]);
-  format_float_2(buf, sizeof(buf), data.phase_power_w[1]);
+  }
-  doc["p2_w"] = serialized(buf);
-  format_float_2(buf, sizeof(buf), data.phase_power_w[2]);
-  doc["p3_w"] = serialized(buf);
   format_float_2(buf, sizeof(buf), data.battery_voltage_v);
   doc["bat_v"] = serialized(buf);
   doc["bat_pct"] = data.battery_percent;
@@ -118,202 +92,11 @@ bool meterDataToJson(const MeterData &data, String &out_json) {
   if (data.err_lora_tx > 0) {
     doc["err_tx"] = data.err_lora_tx;
   }
-  if (data.last_error != FaultType::None) {
   doc["err_last"] = static_cast<uint8_t>(data.last_error);
-  }
+  doc["rx_reject"] = data.rx_reject_reason;
+  doc["rx_reject_text"] = rx_reject_reason_text(static_cast<RxRejectReason>(data.rx_reject_reason));
 
   out_json = "";
   size_t len = serializeJson(doc, out_json);
-  return len > 0 && len < 256;
+  return len > 0 && len < 320;
-}
-
-bool jsonToMeterData(const String &json, MeterData &data) {
-  StaticJsonDocument<256> doc;
-  DeserializationError err = deserializeJson(doc, json);
-  if (err) {
-    return false;
-  }
-
-  const char *id = doc["id"] | "";
-  if (strlen(id) == 4) {
-    snprintf(data.device_id, sizeof(data.device_id), "dd3-%s", id);
-  } else {
-    strncpy(data.device_id, id, sizeof(data.device_id));
-  }
-  data.device_id[sizeof(data.device_id) - 1] = '\0';
-
-  data.ts_utc = doc["ts"] | 0;
-  data.energy_total_kwh = doc["e_kwh"] | NAN;
-  data.total_power_w = doc["p_w"] | NAN;
-  data.phase_power_w[0] = doc["p1_w"] | NAN;
-  data.phase_power_w[1] = doc["p2_w"] | NAN;
-  data.phase_power_w[2] = doc["p3_w"] | NAN;
-  data.battery_voltage_v = doc["bat_v"] | NAN;
-  if (doc["bat_pct"].isNull() && !isnan(data.battery_voltage_v)) {
-    data.battery_percent = battery_percent_from_voltage(data.battery_voltage_v);
-  } else {
-    data.battery_percent = doc["bat_pct"] | 0;
-  }
-  data.valid = true;
-  data.link_valid = false;
-  data.link_rssi_dbm = 0;
-  data.link_snr_db = NAN;
-  data.err_meter_read = doc["err_m"] | 0;
-  data.err_decode = doc["err_d"] | 0;
-  data.err_lora_tx = doc["err_tx"] | 0;
-  data.last_error = static_cast<FaultType>(doc["err_last"] | 0);
-
-  if (strlen(data.device_id) >= 8) {
-    const char *suffix = data.device_id + strlen(data.device_id) - 4;
-    data.short_id = static_cast<uint16_t>(strtoul(suffix, nullptr, 16));
-  }
-
-  return true;
-}
-
-bool meterBatchToJson(const MeterData *samples, size_t count, uint16_t batch_id, String &out_json, const FaultCounters *faults, FaultType last_error) {
-  if (!samples || count == 0) {
-    return false;
-  }
-
-  DynamicJsonDocument doc(8192);
-  doc["schema"] = 1;
-  char sender_label[8] = {};
-  sender_label_from_short_id(samples[count - 1].short_id, sender_label, sizeof(sender_label));
-  doc["sender"] = sender_label;
-  doc["batch_id"] = batch_id;
-  doc["t0"] = samples[0].ts_utc;
-  doc["t_first"] = samples[0].ts_utc;
-  doc["t_last"] = samples[count - 1].ts_utc;
-  uint32_t dt_s = METER_SAMPLE_INTERVAL_MS / 1000;
-  doc["dt_s"] = dt_s > 0 ? dt_s : 1;
-  doc["n"] = static_cast<uint32_t>(count);
-  if (faults) {
-    if (faults->meter_read_fail > 0) {
-      doc["err_m"] = faults->meter_read_fail;
-    }
-    if (faults->lora_tx_fail > 0) {
-      doc["err_tx"] = faults->lora_tx_fail;
-    }
-  }
-  if (last_error != FaultType::None) {
-    doc["err_last"] = static_cast<uint8_t>(last_error);
-  }
-  if (!isnan(samples[count - 1].battery_voltage_v)) {
-    char bat_buf[16];
-    format_float_2(bat_buf, sizeof(bat_buf), samples[count - 1].battery_voltage_v);
-    doc["bat_v"] = serialized(bat_buf);
-  }
-
-  JsonArray energy = doc.createNestedArray("e_wh");
-  JsonArray p_w = doc.createNestedArray("p_w");
-  JsonArray p1_w = doc.createNestedArray("p1_w");
-  JsonArray p2_w = doc.createNestedArray("p2_w");
-  JsonArray p3_w = doc.createNestedArray("p3_w");
-  for (size_t i = 0; i < count; ++i) {
-    energy.add(kwh_to_wh(samples[i].energy_total_kwh));
-    p_w.add(round_to_i32(samples[i].total_power_w));
-    p1_w.add(round_to_i32(samples[i].phase_power_w[0]));
-    p2_w.add(round_to_i32(samples[i].phase_power_w[1]));
-    p3_w.add(round_to_i32(samples[i].phase_power_w[2]));
-  }
-
-  out_json = "";
-  size_t len = serializeJson(doc, out_json);
-  return len > 0;
-}
-
-bool jsonToMeterBatch(const String &json, MeterData *out_samples, size_t max_count, size_t &out_count) {
-  out_count = 0;
-  if (!out_samples || max_count == 0) {
-    return false;
-  }
-
-  DynamicJsonDocument doc(8192);
-  DeserializationError err = deserializeJson(doc, json);
-  if (err) {
-    return false;
-  }
-
-  const char *id = doc["id"] | "";
-  const char *sender = doc["sender"] | "";
-  uint32_t err_m = doc["err_m"] | 0;
-  uint32_t err_tx = doc["err_tx"] | 0;
-  FaultType last_error = static_cast<FaultType>(doc["err_last"] | 0);
-  float bat_v = doc["bat_v"] | NAN;
-
-  if (!doc["schema"].isNull()) {
-    if ((doc["schema"] | 0) != 1) {
-      return false;
-    }
-    size_t count = doc["n"] | 0;
-    if (count == 0) {
-      return false;
-    }
-    if (count > max_count) {
-      count = max_count;
-    }
-
-    uint32_t t0 = doc["t0"] | 0;
-    uint32_t t_first = doc["t_first"] | t0;
-    uint32_t t_last = doc["t_last"] | t_first;
-    uint32_t dt_s = doc["dt_s"] | 1;
-    JsonArray energy = doc["e_wh"].as<JsonArray>();
-    JsonArray p_w = doc["p_w"].as<JsonArray>();
-    JsonArray p1_w = doc["p1_w"].as<JsonArray>();
-    JsonArray p2_w = doc["p2_w"].as<JsonArray>();
-    JsonArray p3_w = doc["p3_w"].as<JsonArray>();
-
-    for (size_t idx = 0; idx < count; ++idx) {
-      MeterData &data = out_samples[idx];
-      data = {};
-      uint16_t short_id = short_id_from_sender_label(sender);
-      if (short_id != 0) {
-        snprintf(data.device_id, sizeof(data.device_id), "dd3-%04X", short_id);
-        data.short_id = short_id;
-      } else if (id[0] != '\0') {
-        strncpy(data.device_id, id, sizeof(data.device_id));
-        data.device_id[sizeof(data.device_id) - 1] = '\0';
-      } else {
-        snprintf(data.device_id, sizeof(data.device_id), "dd3-0000");
-      }
-
-      if (count > 1 && t_last >= t_first) {
-        uint32_t span = t_last - t_first;
-        uint32_t step = span / static_cast<uint32_t>(count - 1);
-        data.ts_utc = t_first + static_cast<uint32_t>(idx) * step;
-      } else {
-        data.ts_utc = t0 + static_cast<uint32_t>(idx) * dt_s;
-      }
-      data.energy_total_kwh = static_cast<float>((energy[idx] | 0)) / 1000.0f;
-      data.total_power_w = static_cast<float>(p_w[idx] | 0);
-      data.phase_power_w[0] = static_cast<float>(p1_w[idx] | 0);
-      data.phase_power_w[1] = static_cast<float>(p2_w[idx] | 0);
-      data.phase_power_w[2] = static_cast<float>(p3_w[idx] | 0);
-      data.battery_voltage_v = bat_v;
-      if (!isnan(bat_v)) {
-        data.battery_percent = battery_percent_from_voltage(bat_v);
-      } else {
-        data.battery_percent = 0;
-      }
-      data.valid = true;
-      data.link_valid = false;
-      data.link_rssi_dbm = 0;
-      data.link_snr_db = NAN;
-      data.err_meter_read = err_m;
-      data.err_decode = 0;
-      data.err_lora_tx = err_tx;
-      data.last_error = last_error;
-
-      if (data.short_id == 0 && strlen(data.device_id) >= 8) {
-        const char *suffix = data.device_id + strlen(data.device_id) - 4;
-        data.short_id = static_cast<uint16_t>(strtoul(suffix, nullptr, 16));
-      }
-    }
-
-    out_count = count;
-    return count > 0;
-  }
-
-  return false;
 }

src/lora_transport.cpp

@@ -3,6 +3,38 @@
 #include <SPI.h>
 #include <math.h>
 
+static RxRejectReason g_last_rx_reject_reason = RxRejectReason::None;
+static uint32_t g_last_rx_reject_log_ms = 0;
+static bool g_last_rx_signal_valid = false;
+static int16_t g_last_rx_rssi_dbm = 0;
+static float g_last_rx_snr_db = 0.0f;
+
+static void note_reject(RxRejectReason reason) {
+  g_last_rx_reject_reason = reason;
+  if (SERIAL_DEBUG_MODE) {
+    uint32_t now_ms = millis();
+    if (now_ms - g_last_rx_reject_log_ms >= 1000) {
+      g_last_rx_reject_log_ms = now_ms;
+      Serial.printf("lora_rx: reject reason=%s\n", rx_reject_reason_text(reason));
+    }
+  }
+}
+
+RxRejectReason lora_get_last_rx_reject_reason() {
+  RxRejectReason reason = g_last_rx_reject_reason;
+  g_last_rx_reject_reason = RxRejectReason::None;
+  return reason;
+}
+
+bool lora_get_last_rx_signal(int16_t &rssi_dbm, float &snr_db) {
+  if (!g_last_rx_signal_valid) {
+    return false;
+  }
+  rssi_dbm = g_last_rx_rssi_dbm;
+  snr_db = g_last_rx_snr_db;
+  return true;
+}
+
 static uint16_t crc16_ccitt(const uint8_t *data, size_t len) {
   uint16_t crc = 0xFFFF;
   for (size_t i = 0; i < len; ++i) {
@@ -33,13 +65,23 @@ bool lora_send(const LoraPacket &pkt) {
   if (LORA_SEND_BYPASS) {
     return true;
   }
-  uint8_t buffer[5 + LORA_MAX_PAYLOAD + 2];
+  uint32_t t0 = 0;
+  uint32_t t1 = 0;
+  uint32_t t2 = 0;
+  uint32_t t3 = 0;
+  uint32_t t4 = 0;
+  if (SERIAL_DEBUG_MODE) {
+    t0 = millis();
+  }
+  LoRa.idle();
+  if (SERIAL_DEBUG_MODE) {
+    t1 = millis();
+  }
+  uint8_t buffer[1 + 2 + LORA_MAX_PAYLOAD + 2];
   size_t idx = 0;
-  buffer[idx++] = pkt.protocol_version;
+  buffer[idx++] = static_cast<uint8_t>(pkt.msg_kind);
-  buffer[idx++] = static_cast<uint8_t>(pkt.role);
   buffer[idx++] = static_cast<uint8_t>(pkt.device_id_short >> 8);
   buffer[idx++] = static_cast<uint8_t>(pkt.device_id_short & 0xFF);
-  buffer[idx++] = static_cast<uint8_t>(pkt.payload_type);
 
   if (pkt.payload_len > LORA_MAX_PAYLOAD) {
     return false;
@@ -53,8 +95,24 @@ bool lora_send(const LoraPacket &pkt) {
   buffer[idx++] = static_cast<uint8_t>(crc & 0xFF);
 
   LoRa.beginPacket();
+  if (SERIAL_DEBUG_MODE) {
+    t2 = millis();
+  }
   LoRa.write(buffer, idx);
-  int result = LoRa.endPacket();
+  if (SERIAL_DEBUG_MODE) {
+    t3 = millis();
+  }
+  int result = LoRa.endPacket(false);
+  if (SERIAL_DEBUG_MODE) {
+    t4 = millis();
+    Serial.printf("lora_tx: idle=%lums begin=%lums write=%lums end=%lums total=%lums len=%u\n",
+                  static_cast<unsigned long>(t1 - t0),
+                  static_cast<unsigned long>(t2 - t1),
+                  static_cast<unsigned long>(t3 - t2),
+                  static_cast<unsigned long>(t4 - t3),
+                  static_cast<unsigned long>(t4 - t0),
+                  static_cast<unsigned>(idx));
+  }
   return result == 1;
 }
 
@@ -63,40 +121,61 @@ bool lora_receive(LoraPacket &pkt, uint32_t timeout_ms) {
   while (true) {
     int packet_size = LoRa.parsePacket();
     if (packet_size > 0) {
-      if (packet_size < 7) {
+      g_last_rx_rssi_dbm = static_cast<int16_t>(LoRa.packetRssi());
+      g_last_rx_snr_db = LoRa.packetSnr();
+      g_last_rx_signal_valid = true;
+
+      if (packet_size < 5) {
         while (LoRa.available()) {
           LoRa.read();
         }
+        note_reject(RxRejectReason::LengthMismatch);
         return false;
       }
 
-      uint8_t buffer[5 + LORA_MAX_PAYLOAD + 2];
+      uint8_t buffer[1 + 2 + LORA_MAX_PAYLOAD + 2];
       size_t len = 0;
       while (LoRa.available() && len < sizeof(buffer)) {
         buffer[len++] = LoRa.read();
       }
+      if (LoRa.available()) {
+        while (LoRa.available()) {
+          LoRa.read();
+        }
+        if (SERIAL_DEBUG_MODE) {
+          Serial.println("rx_reject: oversize packet drained");
+        }
+        note_reject(RxRejectReason::LengthMismatch);
+        return false;
+      }
 
-      if (len < 7) {
+      if (len < 5) {
+        note_reject(RxRejectReason::LengthMismatch);
         return false;
       }
 
       uint16_t crc_calc = crc16_ccitt(buffer, len - 2);
       uint16_t crc_rx = static_cast<uint16_t>(buffer[len - 2] << 8) | buffer[len - 1];
       if (crc_calc != crc_rx) {
+        note_reject(RxRejectReason::CrcFail);
+        return false;
+      }
+      uint8_t msg_kind = buffer[0];
+      if (msg_kind > static_cast<uint8_t>(LoraMsgKind::AckDown)) {
+        note_reject(RxRejectReason::InvalidMsgKind);
         return false;
       }
 
-      pkt.protocol_version = buffer[0];
+      pkt.msg_kind = static_cast<LoraMsgKind>(msg_kind);
-      pkt.role = static_cast<DeviceRole>(buffer[1]);
+      pkt.device_id_short = static_cast<uint16_t>(buffer[1] << 8) | buffer[2];
-      pkt.device_id_short = static_cast<uint16_t>(buffer[2] << 8) | buffer[3];
+      pkt.payload_len = len - 5;
-      pkt.payload_type = static_cast<PayloadType>(buffer[4]);
-      pkt.payload_len = len - 7;
       if (pkt.payload_len > LORA_MAX_PAYLOAD) {
+        note_reject(RxRejectReason::LengthMismatch);
         return false;
       }
-      memcpy(pkt.payload, &buffer[5], pkt.payload_len);
+      memcpy(pkt.payload, &buffer[3], pkt.payload_len);
-      pkt.rssi_dbm = static_cast<int16_t>(LoRa.packetRssi());
+      pkt.rssi_dbm = g_last_rx_rssi_dbm;
-      pkt.snr_db = LoRa.packetSnr();
+      pkt.snr_db = g_last_rx_snr_db;
       return true;
     }
 
@@ -107,10 +186,31 @@ bool lora_receive(LoraPacket &pkt, uint32_t timeout_ms) {
   }
 }
 
+void lora_idle() {
+  LoRa.idle();
+}
+
 void lora_sleep() {
   LoRa.sleep();
 }
 
+void lora_receive_continuous() {
+  LoRa.receive();
+}
+
+bool lora_receive_window(LoraPacket &pkt, uint32_t timeout_ms) {
+  if (timeout_ms == 0) {
+    return false;
+  }
+  g_last_rx_signal_valid = false;
+  g_last_rx_rssi_dbm = 0;
+  g_last_rx_snr_db = 0.0f;
+  LoRa.receive();
+  bool got = lora_receive(pkt, timeout_ms);
+  LoRa.sleep();
+  return got;
+}
+
 uint32_t lora_airtime_ms(size_t packet_len) {
   if (packet_len == 0) {
     return 0;

src/main.cpp

@@ -1,8 +1,7 @@
 #include <Arduino.h>
 #include "config.h"
 #include "data_model.h"
-#include "json_codec.h"
+#include "payload_codec.h"
-#include "compressor.h"
 #include "lora_transport.h"
 #include "meter_driver.h"
 #include "power_manager.h"
@@ -12,8 +11,9 @@
 #include "web_server.h"
 #include "display_ui.h"
 #include "test_mode.h"
-#include <ArduinoJson.h>
+#include "sd_logger.h"
 #include <stdarg.h>
+#include <math.h>
 #ifdef ARDUINO_ARCH_ESP32
 #include <esp_task_wdt.h>
 #include <esp_system.h>
@@ -26,8 +26,6 @@ static char g_device_id[16] = "";
 static SenderStatus g_sender_statuses[NUM_SENDERS];
 static bool g_ap_mode = false;
 static WifiMqttConfig g_cfg;
-static uint32_t g_last_timesync_ms = 0;
-static constexpr uint32_t TIME_SYNC_OFFSET_MS = 15000;
 static uint32_t g_boot_ms = 0;
 static FaultCounters g_sender_faults = {};
 static FaultCounters g_receiver_faults = {};
@@ -51,14 +49,16 @@ static bool g_receiver_discovery_sent = false;
 static constexpr size_t BATCH_HEADER_SIZE = 6;
 static constexpr size_t BATCH_CHUNK_PAYLOAD = LORA_MAX_PAYLOAD - BATCH_HEADER_SIZE;
 static constexpr size_t BATCH_MAX_COMPRESSED = 4096;
-static constexpr size_t BATCH_MAX_DECOMPRESSED = 8192;
 static constexpr uint32_t BATCH_RX_MARGIN_MS = 800;
 
 struct BatchBuffer {
   uint16_t batch_id;
   bool batch_id_valid;
   uint8_t count;
-  MeterData samples[METER_BATCH_MAX_SAMPLES];
+  struct EnergySample {
+    uint32_t ts_utc;
+    uint32_t energy_kwh[3];
+  } samples[METER_BATCH_MAX_SAMPLES];
 };
 
 static BatchBuffer g_batch_queue[BATCH_QUEUE_DEPTH];
@@ -66,7 +66,7 @@ static uint8_t g_batch_head = 0;
 static uint8_t g_batch_tail = 0;
 static uint8_t g_batch_count = 0;
 
-static MeterData g_build_samples[METER_BATCH_MAX_SAMPLES];
+static BatchBuffer::EnergySample g_build_samples[METER_BATCH_MAX_SAMPLES];
 static uint8_t g_build_count = 0;
 
 static uint32_t g_last_sample_ms = 0;
@@ -82,11 +82,21 @@ static uint16_t g_last_acked_batch_id = 0;
 static uint8_t g_batch_retry_count = 0;
 static bool g_batch_ack_pending = false;
 static uint32_t g_batch_ack_timeout_ms = BATCH_ACK_TIMEOUT_MS;
-static MeterData g_inflight_samples[METER_BATCH_MAX_SAMPLES];
+static BatchBuffer::EnergySample g_inflight_samples[METER_BATCH_MAX_SAMPLES];
 static uint8_t g_inflight_count = 0;
 static uint16_t g_inflight_batch_id = 0;
 static bool g_inflight_active = false;
+static bool g_inflight_sync_request = false;
 static uint32_t g_last_debug_log_ms = 0;
+static uint32_t g_sender_rx_window_ms = 0;
+static uint32_t g_sender_sleep_ms = 0;
+static uint32_t g_sender_power_log_ms = 0;
+static RxRejectReason g_sender_rx_reject_reason = RxRejectReason::None;
+static uint32_t g_sender_rx_reject_log_ms = 0;
+static uint32_t g_last_energy_kwh[3] = {};
+static bool g_last_energy_valid[3] = {};
+static bool g_time_acquired = false;
+static uint32_t g_last_sync_request_ms = 0;
 
 static void watchdog_kick();
 
@@ -102,25 +112,6 @@ static void serial_debug_printf(const char *fmt, ...) {
   Serial.println(buf);
 }
 
-static void serial_debug_print_json(const String &json) {
-  if (!SERIAL_DEBUG_MODE || !SERIAL_DEBUG_DUMP_JSON) {
-    return;
-  }
-  const char *data = json.c_str();
-  size_t len = json.length();
-  const size_t chunk = 128;
-  for (size_t i = 0; i < len; i += chunk) {
-    size_t n = len - i;
-    if (n > chunk) {
-      n = chunk;
-    }
-    Serial.write(reinterpret_cast<const uint8_t *>(data + i), n);
-    watchdog_kick();
-    delay(0);
-  }
-  Serial.write('\n');
-}
-
 static uint16_t g_last_batch_id_rx[NUM_SENDERS] = {};
 
 struct BatchRxState {
@@ -142,6 +133,7 @@ static void init_sender_statuses() {
     g_sender_statuses[i] = {};
     g_sender_statuses[i].has_data = false;
     g_sender_statuses[i].last_update_ts_utc = 0;
+    g_sender_statuses[i].last_acked_batch_id = 0;
     g_sender_statuses[i].last_data.short_id = EXPECTED_SENDER_IDS[i];
     snprintf(g_sender_statuses[i].last_data.device_id, sizeof(g_sender_statuses[i].last_data.device_id), "dd3-%04X", EXPECTED_SENDER_IDS[i]);
     g_sender_faults_remote[i] = {};
@@ -162,6 +154,10 @@ static void update_battery_cache() {
   g_last_battery_ms = millis();
 }
 
+static bool battery_sample_due(uint32_t now_ms) {
+  return g_last_battery_ms == 0 || now_ms - g_last_battery_ms >= BATTERY_SAMPLE_INTERVAL_MS;
+}
+
 static bool batch_queue_drop_oldest() {
   if (g_batch_count == 0) {
     return false;
@@ -174,12 +170,25 @@ static bool batch_queue_drop_oldest() {
     g_inflight_active = false;
     g_inflight_count = 0;
     g_inflight_batch_id = 0;
+    g_inflight_sync_request = false;
   }
   g_batch_tail = (g_batch_tail + 1) % BATCH_QUEUE_DEPTH;
   g_batch_count--;
   return dropped_inflight;
 }
 
+static void sender_note_rx_reject(RxRejectReason reason, const char *context) {
+  if (reason == RxRejectReason::None) {
+    return;
+  }
+  g_sender_rx_reject_reason = reason;
+  uint32_t now_ms = millis();
+  if (SERIAL_DEBUG_MODE && now_ms - g_sender_rx_reject_log_ms >= 1000) {
+    g_sender_rx_reject_log_ms = now_ms;
+    serial_debug_printf("rx_reject: %s reason=%s", context, rx_reject_reason_text(reason));
+  }
+}
+
 static BatchBuffer *batch_queue_peek() {
   if (g_batch_count == 0) {
     return nullptr;
@@ -187,7 +196,7 @@ static BatchBuffer *batch_queue_peek() {
   return &g_batch_queue[g_batch_tail];
 }
 
-static void batch_queue_enqueue(const MeterData *samples, uint8_t count) {
+static void batch_queue_enqueue(const BatchBuffer::EnergySample *samples, uint8_t count) {
   if (!samples || count == 0) {
     return;
   }
@@ -283,13 +292,66 @@ static uint16_t read_u16_le(const uint8_t *src) {
   return static_cast<uint16_t>(src[0]) | (static_cast<uint16_t>(src[1]) << 8);
 }
 
+static void write_u16_be(uint8_t *dst, uint16_t value) {
+  dst[0] = static_cast<uint8_t>((value >> 8) & 0xFF);
+  dst[1] = static_cast<uint8_t>(value & 0xFF);
+}
+
+static uint16_t read_u16_be(const uint8_t *src) {
+  return static_cast<uint16_t>(src[0] << 8) | static_cast<uint16_t>(src[1]);
+}
+
+static void write_u32_be(uint8_t *dst, uint32_t value) {
+  dst[0] = static_cast<uint8_t>((value >> 24) & 0xFF);
+  dst[1] = static_cast<uint8_t>((value >> 16) & 0xFF);
+  dst[2] = static_cast<uint8_t>((value >> 8) & 0xFF);
+  dst[3] = static_cast<uint8_t>(value & 0xFF);
+}
+
+static uint32_t read_u32_be(const uint8_t *src) {
+  return (static_cast<uint32_t>(src[0]) << 24) |
+      (static_cast<uint32_t>(src[1]) << 16) |
+      (static_cast<uint32_t>(src[2]) << 8) |
+      static_cast<uint32_t>(src[3]);
+}
+
+static uint16_t sender_id_from_short_id(uint16_t short_id) {
+  for (uint8_t i = 0; i < NUM_SENDERS; ++i) {
+    if (EXPECTED_SENDER_IDS[i] == short_id) {
+      return static_cast<uint16_t>(i + 1);
+    }
+  }
+  return 0;
+}
+
+static uint16_t short_id_from_sender_id(uint16_t sender_id) {
+  if (sender_id == 0 || sender_id > NUM_SENDERS) {
+    return 0;
+  }
+  return EXPECTED_SENDER_IDS[sender_id - 1];
+}
+
+static uint16_t battery_mv_from_voltage(float value) {
+  if (isnan(value) || value <= 0.0f) {
+    return 0;
+  }
+  long mv = lroundf(value * 1000.0f);
+  if (mv < 0) {
+    mv = 0;
+  }
+  if (mv > UINT16_MAX) {
+    mv = UINT16_MAX;
+  }
+  return static_cast<uint16_t>(mv);
+}
+
 static uint32_t compute_batch_rx_timeout_ms(uint16_t total_len, uint8_t chunk_count) {
   if (total_len == 0 || chunk_count == 0) {
     return 10000;
   }
   size_t max_chunk_payload = total_len > BATCH_CHUNK_PAYLOAD ? BATCH_CHUNK_PAYLOAD : total_len;
   size_t payload_len = BATCH_HEADER_SIZE + max_chunk_payload;
-  size_t packet_len = 5 + payload_len + 2;
+  size_t packet_len = 3 + payload_len + 2;
   uint32_t per_chunk_toa_ms = lora_airtime_ms(packet_len);
   uint32_t timeout_ms = static_cast<uint32_t>(chunk_count) * per_chunk_toa_ms + BATCH_RX_MARGIN_MS;
   return timeout_ms < 10000 ? 10000 : timeout_ms;
@@ -300,28 +362,12 @@ static uint32_t compute_batch_ack_timeout_ms(size_t payload_len) {
     return 10000;
   }
   uint8_t chunk_count = static_cast<uint8_t>((payload_len + BATCH_CHUNK_PAYLOAD - 1) / BATCH_CHUNK_PAYLOAD);
-  size_t packet_len = 5 + BATCH_HEADER_SIZE + (payload_len > BATCH_CHUNK_PAYLOAD ? BATCH_CHUNK_PAYLOAD : payload_len) + 2;
+  size_t packet_len = 3 + BATCH_HEADER_SIZE + (payload_len > BATCH_CHUNK_PAYLOAD ? BATCH_CHUNK_PAYLOAD : payload_len) + 2;
   uint32_t per_chunk_toa_ms = lora_airtime_ms(packet_len);
   uint32_t timeout_ms = static_cast<uint32_t>(chunk_count) * per_chunk_toa_ms + BATCH_RX_MARGIN_MS;
   return timeout_ms < 10000 ? 10000 : timeout_ms;
 }
 
-static bool inject_batch_meta(String &json, int16_t rssi_dbm, float snr_db, uint32_t rx_ts_utc) {
-  DynamicJsonDocument doc(8192);
-  DeserializationError err = deserializeJson(doc, json);
-  if (err) {
-    return false;
-  }
-
-  JsonObject meta = doc.createNestedObject("meta");
-  meta["rssi"] = rssi_dbm;
-  meta["snr"] = snr_db;
-  meta["rx_ts"] = rx_ts_utc;
-
-  json = "";
-  return serializeJson(doc, json) > 0;
-}
-
 static bool send_batch_payload(const uint8_t *data, size_t len, uint32_t ts_for_display, uint16_t batch_id) {
   if (!data || len == 0 || len > BATCH_MAX_COMPRESSED) {
     return false;
@@ -339,10 +385,8 @@ static bool send_batch_payload(const uint8_t *data, size_t len, uint32_t ts_for_
       chunk_len = BATCH_CHUNK_PAYLOAD;
     }
     LoraPacket pkt = {};
-    pkt.protocol_version = PROTOCOL_VERSION;
+    pkt.msg_kind = LoraMsgKind::BatchUp;
-    pkt.role = DeviceRole::Sender;
     pkt.device_id_short = g_short_id;
-    pkt.payload_type = PayloadType::MeterBatch;
     pkt.payload_len = chunk_len + BATCH_HEADER_SIZE;
 
     uint8_t *payload = pkt.payload;
@@ -373,17 +417,32 @@ static bool send_batch_payload(const uint8_t *data, size_t len, uint32_t ts_for_
   return all_ok;
 }
 
-static void send_batch_ack(uint16_t batch_id, uint16_t sender_id) {
+static void send_batch_ack(uint16_t batch_id, uint8_t sample_count) {
+  uint32_t epoch = time_get_utc();
+  uint8_t time_valid = (time_is_synced() && epoch >= MIN_ACCEPTED_EPOCH_UTC) ? 1 : 0;
+  if (!time_valid) {
+    epoch = 0;
+  }
   LoraPacket ack = {};
-  ack.protocol_version = PROTOCOL_VERSION;
+  ack.msg_kind = LoraMsgKind::AckDown;
-  ack.role = DeviceRole::Receiver;
   ack.device_id_short = g_short_id;
-  ack.payload_type = PayloadType::Ack;
+  ack.payload_len = LORA_ACK_DOWN_PAYLOAD_LEN;
-  ack.payload_len = 6;
+  ack.payload[0] = time_valid;
-  write_u16_le(&ack.payload[0], batch_id);
+  write_u16_be(&ack.payload[1], batch_id);
-  write_u16_le(&ack.payload[2], sender_id);
+  write_u32_be(&ack.payload[3], epoch);
-  write_u16_le(&ack.payload[4], g_short_id);
+  uint8_t repeats = ACK_REPEAT_COUNT == 0 ? 1 : ACK_REPEAT_COUNT;
+  for (uint8_t i = 0; i < repeats; ++i) {
     lora_send(ack);
+    if (i + 1 < repeats && ACK_REPEAT_DELAY_MS > 0) {
+      delay(ACK_REPEAT_DELAY_MS);
+    }
+  }
+  serial_debug_printf("ack: tx batch_id=%u time_valid=%u epoch=%lu samples=%u",
+                      batch_id,
+                      static_cast<unsigned>(time_valid),
+                      static_cast<unsigned long>(epoch),
+                      static_cast<unsigned>(sample_count));
+  lora_receive_continuous();
 }
 
 static bool prepare_inflight_from_queue() {
@@ -408,47 +467,67 @@ static bool prepare_inflight_from_queue() {
 }
 
 static bool send_inflight_batch(uint32_t ts_for_display) {
-  if (!g_inflight_active || g_inflight_count == 0) {
+  if (!g_inflight_active) {
     return false;
   }
-  uint32_t json_start = millis();
+  BatchInput input = {};
-  String json;
+  input.schema_id = 1;
-  if (!meterBatchToJson(g_inflight_samples, g_inflight_count, g_inflight_batch_id, json, &g_sender_faults, g_sender_last_error)) {
+  input.sender_id = sender_id_from_short_id(g_short_id);
-    return false;
+  input.batch_id = g_inflight_batch_id;
-  }
+  input.t_last = g_inflight_sync_request ? time_get_utc() :
-  uint32_t json_ms = millis() - json_start;
+      g_inflight_samples[g_inflight_count - 1].ts_utc;
-  if (SERIAL_DEBUG_MODE) {
+  uint32_t dt_s = METER_SAMPLE_INTERVAL_MS / 1000;
-    serial_debug_printf("tx: batch_id=%u count=%u json_len=%u", g_inflight_batch_id, g_inflight_count, static_cast<unsigned>(json.length()));
+  input.dt_s = dt_s > 0 ? static_cast<uint8_t>(dt_s) : 1;
-    if (json_ms > 200) {
+  input.n = g_inflight_sync_request ? 0 : g_inflight_count;
-      serial_debug_printf("tx: json encode took %lums", static_cast<unsigned long>(json_ms));
+  input.meter_count = METER_COUNT;
-    }
+  input.battery_mV = battery_mv_from_voltage(g_last_battery_voltage_v);
-    serial_debug_print_json(json);
+  input.err_m = g_sender_faults.meter_read_fail > 255 ? 255 : static_cast<uint8_t>(g_sender_faults.meter_read_fail);
+  input.err_d = g_sender_faults.decode_fail > 255 ? 255 : static_cast<uint8_t>(g_sender_faults.decode_fail);
+  input.err_tx = g_sender_faults.lora_tx_fail > 255 ? 255 : static_cast<uint8_t>(g_sender_faults.lora_tx_fail);
+  input.err_last = static_cast<uint8_t>(g_sender_last_error);
+  input.err_rx_reject = static_cast<uint8_t>(g_sender_rx_reject_reason);
+  for (uint8_t i = 0; i < input.n; ++i) {
+    input.energy1_kwh[i] = g_inflight_samples[i].energy_kwh[0];
+    input.energy2_kwh[i] = g_inflight_samples[i].energy_kwh[1];
+    input.energy3_kwh[i] = g_inflight_samples[i].energy_kwh[2];
   }
 
-  static uint8_t compressed[BATCH_MAX_COMPRESSED];
+  static uint8_t encoded[BATCH_MAX_COMPRESSED];
-  size_t compressed_len = 0;
+  size_t encoded_len = 0;
-  uint32_t compress_start = millis();
+  uint32_t encode_start = millis();
-  if (!compressBuffer(reinterpret_cast<const uint8_t *>(json.c_str()), json.length(), compressed, sizeof(compressed), compressed_len)) {
+  if (!encode_batch(input, encoded, sizeof(encoded), &encoded_len)) {
     return false;
   }
-  uint32_t compress_ms = millis() - compress_start;
+  uint32_t encode_ms = millis() - encode_start;
-  if (SERIAL_DEBUG_MODE && compress_ms > 200) {
+  if (SERIAL_DEBUG_MODE) {
-    serial_debug_printf("tx: compress took %lums", static_cast<unsigned long>(compress_ms));
+    serial_debug_printf("tx: batch_id=%u count=%u bin_len=%u", g_inflight_batch_id, input.n,
+                        static_cast<unsigned>(encoded_len));
+    if (encode_ms > 200) {
+      serial_debug_printf("tx: encode took %lums", static_cast<unsigned long>(encode_ms));
     }
-  g_batch_ack_timeout_ms = compute_batch_ack_timeout_ms(compressed_len);
+  }
+  g_batch_ack_timeout_ms = compute_batch_ack_timeout_ms(encoded_len);
 
   uint32_t send_start = millis();
-  bool ok = send_batch_payload(compressed, compressed_len, ts_for_display, g_inflight_batch_id);
+  bool ok = send_batch_payload(encoded, encoded_len, ts_for_display, g_inflight_batch_id);
   uint32_t send_ms = millis() - send_start;
   if (SERIAL_DEBUG_MODE && send_ms > 1000) {
     serial_debug_printf("tx: send batch took %lums", static_cast<unsigned long>(send_ms));
   }
   if (ok) {
     g_last_batch_send_ms = millis();
-    serial_debug_printf("tx: sent batch_id=%u len=%u", g_inflight_batch_id, static_cast<unsigned>(compressed_len));
+    if (g_inflight_sync_request) {
+      serial_debug_printf("sync: request tx batch_id=%u", g_inflight_batch_id);
+    } else {
+      serial_debug_printf("tx: sent batch_id=%u len=%u", g_inflight_batch_id, static_cast<unsigned>(encoded_len));
+    }
+  } else {
+    if (g_inflight_sync_request) {
+      serial_debug_printf("sync: request tx failed batch_id=%u", g_inflight_batch_id);
     } else {
       serial_debug_printf("tx: send failed batch_id=%u", g_inflight_batch_id);
     }
+  }
   return ok;
 }
 
@@ -456,6 +535,7 @@ static bool send_meter_batch(uint32_t ts_for_display) {
   if (!prepare_inflight_from_queue()) {
     return false;
   }
+  g_inflight_sync_request = false;
   bool ok = send_inflight_batch(ts_for_display);
   if (ok) {
     g_last_sent_batch_id = g_inflight_batch_id;
@@ -464,12 +544,36 @@ static bool send_meter_batch(uint32_t ts_for_display) {
     g_inflight_active = false;
     g_inflight_count = 0;
     g_inflight_batch_id = 0;
+    g_inflight_sync_request = false;
+  }
+  return ok;
+}
+
+static bool send_sync_request() {
+  if (g_batch_ack_pending) {
+    return false;
+  }
+  if (battery_sample_due(millis())) {
+    update_battery_cache();
+  }
+  g_inflight_active = true;
+  g_inflight_sync_request = true;
+  g_inflight_count = 0;
+  g_inflight_batch_id = g_batch_id;
+  bool ok = send_inflight_batch(time_get_utc());
+  if (ok) {
+    g_last_sent_batch_id = g_inflight_batch_id;
+    g_batch_ack_pending = true;
+  } else {
+    g_inflight_active = false;
+    g_inflight_sync_request = false;
+    g_inflight_batch_id = 0;
   }
   return ok;
 }
 
 static bool resend_inflight_batch(uint32_t ts_for_display) {
-  if (!g_batch_ack_pending || !g_inflight_active || g_inflight_count == 0) {
+  if (!g_batch_ack_pending || !g_inflight_active || (!g_inflight_sync_request && g_inflight_count == 0)) {
     return false;
   }
   return send_inflight_batch(ts_for_display);
@@ -484,6 +588,7 @@ static void finish_inflight_batch() {
   g_inflight_active = false;
   g_inflight_count = 0;
   g_inflight_batch_id = 0;
+  g_inflight_sync_request = false;
   g_batch_id++;
 }
 
@@ -498,7 +603,7 @@ static void reset_batch_rx() {
   g_batch_rx.timeout_ms = 0;
 }
 
-static bool process_batch_packet(const LoraPacket &pkt, String &out_json, bool &decode_error, uint16_t &out_batch_id) {
+static bool process_batch_packet(const LoraPacket &pkt, BatchInput &out_batch, bool &decode_error, uint16_t &out_batch_id) {
   decode_error = false;
   if (pkt.payload_len < BATCH_HEADER_SIZE) {
     return false;
@@ -545,20 +650,11 @@ static bool process_batch_packet(const LoraPacket &pkt, String &out_json, bool &
   g_batch_rx.last_rx_ms = now_ms;
 
   if (g_batch_rx.next_index == g_batch_rx.expected_chunks && g_batch_rx.received_len == g_batch_rx.total_len) {
-    static uint8_t decompressed[BATCH_MAX_DECOMPRESSED];
+    if (!decode_batch(g_batch_rx.buffer, g_batch_rx.received_len, &out_batch)) {
-    size_t decompressed_len = 0;
-    if (!decompressBuffer(g_batch_rx.buffer, g_batch_rx.received_len, decompressed, sizeof(decompressed) - 1, decompressed_len)) {
       decode_error = true;
       reset_batch_rx();
       return false;
     }
-    if (decompressed_len >= sizeof(decompressed)) {
-      decode_error = true;
-      reset_batch_rx();
-      return false;
-    }
-    decompressed[decompressed_len] = '\0';
-    out_json = String(reinterpret_cast<const char *>(decompressed));
     out_batch_id = batch_id;
     reset_batch_rx();
     return true;
@@ -568,13 +664,19 @@ static bool process_batch_packet(const LoraPacket &pkt, String &out_json, bool &
 }
 
 void setup() {
+  if (SERIAL_DEBUG_MODE) {
     Serial.begin(115200);
     delay(200);
+  }
+#ifdef PAYLOAD_CODEC_TEST
+  payload_codec_self_test();
+#endif
 
   watchdog_init();
   g_boot_ms = millis();
   g_role = detect_role();
   init_device_ids(g_short_id, g_device_id, sizeof(g_device_id));
+  display_set_role(g_role);
   if (SERIAL_DEBUG_MODE) {
 #ifdef ARDUINO_ARCH_ESP32
     serial_debug_printf("boot: reset_reason=%d", static_cast<int>(esp_reset_reason()));
@@ -585,19 +687,22 @@ void setup() {
 
   lora_init();
   display_init();
-  time_rtc_init();
-  time_try_load_from_rtc();
-  display_set_role(g_role);
   display_set_self_ids(g_short_id, g_device_id);
 
   if (g_role == DeviceRole::Sender) {
     power_sender_init();
+    power_configure_unused_pins_sender();
     meter_init();
     g_last_sample_ms = millis() - METER_SAMPLE_INTERVAL_MS;
     g_last_send_ms = millis();
+    g_last_sync_request_ms = millis() - SYNC_REQUEST_INTERVAL_MS;
+    g_time_acquired = false;
     update_battery_cache();
   } else {
     power_receiver_init();
+    lora_receive_continuous();
+    pinMode(PIN_ROLE, INPUT); // release pulldown before SD uses GPIO14 as SCK
+    sd_logger_init();
     wifi_manager_init();
     init_sender_statuses();
     display_set_sender_statuses(g_sender_statuses, NUM_SENDERS);
@@ -613,8 +718,8 @@ void setup() {
     } else {
       g_ap_mode = true;
       char ap_ssid[32];
-      snprintf(ap_ssid, sizeof(ap_ssid), "DD3-Bridge-%04X", g_short_id);
+      snprintf(ap_ssid, sizeof(ap_ssid), "%s%04X", AP_SSID_PREFIX, g_short_id);
-      wifi_start_ap(ap_ssid, "changeme123");
+      wifi_start_ap(ap_ssid, AP_PASSWORD);
       if (g_cfg.ntp_server_1.isEmpty()) {
         g_cfg.ntp_server_1 = "pool.ntp.org";
       }
@@ -645,80 +750,166 @@ static void sender_loop() {
                         g_batch_retry_count);
   }
 
+  if (g_time_acquired) {
+    meter_poll();
+    for (uint8_t i = 0; i < meter_count() && i < 3; ++i) {
+      uint32_t e_kwh = 0;
+      if (meter_get_last_energy_kwh(i, e_kwh)) {
+        g_last_energy_kwh[i] = e_kwh;
+        g_last_energy_valid[i] = true;
+      }
+    }
+
     if (now_ms - g_last_sample_ms >= METER_SAMPLE_INTERVAL_MS) {
       g_last_sample_ms = now_ms;
-    MeterData data = {};
+      bool any_meter_valid = false;
-    data.short_id = g_short_id;
+      for (uint8_t i = 0; i < meter_count() && i < 3; ++i) {
-    strncpy(data.device_id, g_device_id, sizeof(data.device_id));
+        if (g_last_energy_valid[i]) {
-
+          any_meter_valid = true;
-    bool meter_ok = meter_read(data);
+          break;
-    if (!meter_ok) {
+        }
+      }
+      if (!any_meter_valid) {
         note_fault(g_sender_faults, g_sender_last_error, g_sender_last_error_utc, g_sender_last_error_ms, FaultType::MeterRead);
         display_set_last_error(g_sender_last_error, g_sender_last_error_utc, g_sender_last_error_ms);
-    }
+      } else {
-    if (g_build_count == 0) {
+        BatchBuffer::EnergySample sample = {};
-      update_battery_cache();
+        sample.ts_utc = time_get_utc();
-    }
+        sample.energy_kwh[0] = g_last_energy_valid[0] ? g_last_energy_kwh[0] : 0;
-    data.battery_voltage_v = g_last_battery_voltage_v;
+        sample.energy_kwh[1] = g_last_energy_valid[1] ? g_last_energy_kwh[1] : 0;
-    data.battery_percent = g_last_battery_percent;
+        sample.energy_kwh[2] = (meter_count() >= 3 && g_last_energy_valid[2]) ? g_last_energy_kwh[2] : 0;
-
+        g_last_sample_ts_utc = sample.ts_utc;
-    uint32_t now_utc = time_get_utc();
+        g_build_samples[g_build_count++] = sample;
-    data.ts_utc = now_utc > 0 ? now_utc : millis() / 1000;
-    data.valid = meter_ok;
-
-    g_last_sample_ts_utc = data.ts_utc;
-    g_build_samples[g_build_count++] = data;
         if (g_build_count >= METER_BATCH_MAX_SAMPLES) {
           batch_queue_enqueue(g_build_samples, g_build_count);
           g_build_count = 0;
         }
-    display_set_last_meter(data);
+
-    display_set_last_read(meter_ok, data.ts_utc);
+        MeterData view = {};
+        view.short_id = g_short_id;
+        strncpy(view.device_id, g_device_id, sizeof(view.device_id));
+        view.ts_utc = sample.ts_utc;
+        view.energy_multi = true;
+        view.energy_meter_count = meter_count();
+        view.energy_kwh_int[0] = sample.energy_kwh[0];
+        view.energy_kwh_int[1] = sample.energy_kwh[1];
+        view.energy_kwh_int[2] = sample.energy_kwh[2];
+        view.energy_total_kwh = static_cast<float>(sample.energy_kwh[0]);
+        view.valid = true;
+        view.battery_voltage_v = g_last_battery_voltage_v;
+        view.battery_percent = g_last_battery_percent;
+        display_set_last_meter(view);
+        display_set_last_read(true, view.ts_utc);
+      }
+
+      if (g_build_count == 0 && battery_sample_due(now_ms)) {
+        update_battery_cache();
+      }
     }
 
     if (!g_batch_ack_pending && now_ms - g_last_send_ms >= METER_SEND_INTERVAL_MS) {
       g_last_send_ms = now_ms;
       send_meter_batch(last_sample_ts());
     }
+  } else {
+    if (!g_batch_ack_pending && now_ms - g_last_sync_request_ms >= SYNC_REQUEST_INTERVAL_MS) {
+      g_last_sync_request_ms = now_ms;
+      send_sync_request();
+    }
+  }
 
   if (g_batch_ack_pending) {
-    uint32_t end_ms = millis() + 400;
-    while (millis() < end_ms) {
     LoraPacket ack_pkt = {};
-      if (!lora_receive(ack_pkt, 0) || ack_pkt.protocol_version != PROTOCOL_VERSION) {
+    constexpr size_t ack_len = lora_frame_size(LORA_ACK_DOWN_PAYLOAD_LEN);
-        delay(5);
+    uint32_t ack_air_ms = lora_airtime_ms(ack_len);
-        continue;
+    uint32_t ack_window_ms = ack_air_ms + 300;
+    if (ack_window_ms < 1200) {
+      ack_window_ms = 1200;
+    }
+    if (ack_window_ms > 4000) {
+      ack_window_ms = 4000;
+    }
+    if (SERIAL_DEBUG_MODE) {
+      serial_debug_printf("ack: rx window=%lu airtime=%lu", static_cast<unsigned long>(ack_window_ms),
+                          static_cast<unsigned long>(ack_air_ms));
+    }
+    uint32_t rx_start = millis();
+    bool got_ack = lora_receive_window(ack_pkt, ack_window_ms);
+    if (!got_ack) {
+      got_ack = lora_receive_window(ack_pkt, ack_window_ms / 2);
+    }
+    uint32_t rx_elapsed = millis() - rx_start;
+    if (SERIAL_DEBUG_MODE) {
+      g_sender_rx_window_ms += rx_elapsed;
+    }
+    if (!got_ack) {
+      RxRejectReason reason = lora_get_last_rx_reject_reason();
+      sender_note_rx_reject(reason, "ack");
+      if (SERIAL_DEBUG_MODE) {
+        int16_t rssi_dbm = 0;
+        float snr_db = 0.0f;
+        bool has_signal = lora_get_last_rx_signal(rssi_dbm, snr_db);
+        const char *reason_text = reason == RxRejectReason::None ? "timeout" : rx_reject_reason_text(reason);
+        if (has_signal) {
+          serial_debug_printf("ack: rx miss reason=%s rssi=%d snr=%.1f",
+                              reason_text,
+                              static_cast<int>(rssi_dbm),
+                              static_cast<double>(snr_db));
+        } else {
+          serial_debug_printf("ack: rx miss reason=%s", reason_text);
+        }
+      }
+    } else if (ack_pkt.msg_kind != LoraMsgKind::AckDown) {
+      sender_note_rx_reject(RxRejectReason::InvalidMsgKind, "ack");
+      if (SERIAL_DEBUG_MODE) {
+        uint16_t ack_id = ack_pkt.payload_len >= 3 ? read_u16_be(&ack_pkt.payload[1]) : 0;
+        serial_debug_printf("ack: reject msg_kind=%u payload_len=%u ack_id=%u",
+                            static_cast<unsigned>(ack_pkt.msg_kind),
+                            static_cast<unsigned>(ack_pkt.payload_len),
+                            ack_id);
+      }
+    } else if (ack_pkt.payload_len < LORA_ACK_DOWN_PAYLOAD_LEN) {
+      sender_note_rx_reject(RxRejectReason::LengthMismatch, "ack");
+      if (SERIAL_DEBUG_MODE) {
+        uint16_t ack_id = ack_pkt.payload_len >= 3 ? read_u16_be(&ack_pkt.payload[1]) : 0;
+        serial_debug_printf("ack: reject msg_kind=%u payload_len=%u ack_id=%u",
+                            static_cast<unsigned>(ack_pkt.msg_kind),
+                            static_cast<unsigned>(ack_pkt.payload_len),
+                            ack_id);
+      }
+    } else {
+      uint8_t time_valid = ack_pkt.payload[0] & 0x01;
+      uint16_t ack_id = read_u16_be(&ack_pkt.payload[1]);
+      uint32_t ack_epoch = read_u32_be(&ack_pkt.payload[3]);
+      bool set_time = false;
+      if (g_batch_ack_pending && ack_id == g_last_sent_batch_id) {
+        if (time_valid == 1 && ack_epoch >= MIN_ACCEPTED_EPOCH_UTC) {
+          time_set_utc(ack_epoch);
+          g_time_acquired = true;
+          set_time = true;
         }
-      if (ack_pkt.payload_type == PayloadType::Ack && ack_pkt.payload_len >= 6 && ack_pkt.role == DeviceRole::Receiver) {
-        uint16_t ack_id = read_u16_le(ack_pkt.payload);
-        uint16_t ack_sender = read_u16_le(&ack_pkt.payload[2]);
-        uint16_t ack_receiver = read_u16_le(&ack_pkt.payload[4]);
-        if (ack_sender == g_short_id && ack_receiver == ack_pkt.device_id_short &&
-            g_batch_ack_pending && ack_id == g_last_sent_batch_id) {
         g_last_acked_batch_id = ack_id;
-          serial_debug_printf("ack: ok batch_id=%u", ack_id);
+        serial_debug_printf("ack: rx ok batch_id=%u time_valid=%u epoch=%lu set=%u",
+                            ack_id,
+                            static_cast<unsigned>(time_valid),
+                            static_cast<unsigned long>(ack_epoch),
+                            set_time ? 1 : 0);
         finish_inflight_batch();
-          break;
+      } else {
+        if (ack_id != g_last_sent_batch_id) {
+          sender_note_rx_reject(RxRejectReason::BatchIdMismatch, "ack");
+          if (SERIAL_DEBUG_MODE) {
+            serial_debug_printf("ack: reject msg_kind=%u payload_len=%u ack_id=%u",
+                                static_cast<unsigned>(ack_pkt.msg_kind),
+                                static_cast<unsigned>(ack_pkt.payload_len),
+                                ack_id);
           }
         }
       }
     }
-
-  LoraPacket rx = {};
-  if (lora_receive(rx, 0) && rx.protocol_version == PROTOCOL_VERSION) {
-    if (rx.payload_type == PayloadType::TimeSync) {
-      time_handle_timesync_payload(rx.payload, rx.payload_len);
-    } else if (rx.payload_type == PayloadType::Ack && rx.payload_len >= 6 && rx.role == DeviceRole::Receiver) {
-      uint16_t ack_id = read_u16_le(rx.payload);
-      uint16_t ack_sender = read_u16_le(&rx.payload[2]);
-      uint16_t ack_receiver = read_u16_le(&rx.payload[4]);
-      if (ack_sender == g_short_id && ack_receiver == rx.device_id_short &&
-          g_batch_ack_pending && ack_id == g_last_sent_batch_id) {
-        g_last_acked_batch_id = ack_id;
-        serial_debug_printf("ack: ok batch_id=%u", ack_id);
-        finish_inflight_batch();
-      }
   }
+  if (!g_batch_ack_pending) {
+    lora_sleep();
   }
 
   if (g_batch_ack_pending && (now_ms - g_last_batch_send_ms >= g_batch_ack_timeout_ms)) {
@@ -737,6 +928,7 @@ static void sender_loop() {
         g_inflight_active = false;
         g_inflight_count = 0;
         g_inflight_batch_id = 0;
+        g_inflight_sync_request = false;
       }
       note_fault(g_sender_faults, g_sender_last_error, g_sender_last_error_utc, g_sender_last_error_ms, FaultType::LoraTx);
       display_set_last_error(g_sender_last_error, g_sender_last_error_utc, g_sender_last_error_ms);
@@ -745,78 +937,38 @@ static void sender_loop() {
 
   display_tick();
 
-  uint32_t next_sample_due = g_last_sample_ms + METER_SAMPLE_INTERVAL_MS;
+  uint32_t next_due = g_time_acquired ? (g_last_sample_ms + METER_SAMPLE_INTERVAL_MS) :
+      (g_last_sync_request_ms + SYNC_REQUEST_INTERVAL_MS);
+  if (g_time_acquired) {
     uint32_t next_send_due = g_last_send_ms + METER_SEND_INTERVAL_MS;
-  uint32_t next_due = next_sample_due < next_send_due ? next_sample_due : next_send_due;
+    if (next_send_due < next_due) {
+      next_due = next_send_due;
+    }
+  }
   if (!g_batch_ack_pending && next_due > now_ms) {
     watchdog_kick();
+    if (SERIAL_DEBUG_MODE) {
+      g_sender_sleep_ms += (next_due - now_ms);
+      if (now_ms - g_sender_power_log_ms >= 10000) {
+        g_sender_power_log_ms = now_ms;
+        serial_debug_printf("power: rx_ms=%lu sleep_ms=%lu", static_cast<unsigned long>(g_sender_rx_window_ms),
+                            static_cast<unsigned long>(g_sender_sleep_ms));
+      }
+    }
+    lora_sleep();
     light_sleep_ms(next_due - now_ms);
   }
 }
 
 static void receiver_loop() {
   watchdog_kick();
-  if (g_last_timesync_ms == 0) {
-    g_last_timesync_ms = millis() - (TIME_SYNC_INTERVAL_SEC * 1000UL - TIME_SYNC_OFFSET_MS);
-  }
   LoraPacket pkt = {};
-  if (lora_receive(pkt, 0) && pkt.protocol_version == PROTOCOL_VERSION) {
+  if (lora_receive(pkt, 0)) {
-    if (pkt.payload_type == PayloadType::MeterData) {
+    if (pkt.msg_kind == LoraMsgKind::BatchUp) {
-      uint8_t decompressed[256];
+      BatchInput batch = {};
-      size_t decompressed_len = 0;
-      if (!decompressBuffer(pkt.payload, pkt.payload_len, decompressed, sizeof(decompressed) - 1, decompressed_len)) {
-        note_fault(g_receiver_faults, g_receiver_last_error, g_receiver_last_error_utc, g_receiver_last_error_ms, FaultType::Decode);
-        display_set_last_error(g_receiver_last_error, g_receiver_last_error_utc, g_receiver_last_error_ms);
-      } else {
-        if (decompressed_len >= sizeof(decompressed)) {
-          note_fault(g_receiver_faults, g_receiver_last_error, g_receiver_last_error_utc, g_receiver_last_error_ms, FaultType::Decode);
-          display_set_last_error(g_receiver_last_error, g_receiver_last_error_utc, g_receiver_last_error_ms);
-          return;
-        }
-        decompressed[decompressed_len] = '\0';
-        MeterData data = {};
-        if (jsonToMeterData(String(reinterpret_cast<const char *>(decompressed)), data)) {
-          data.link_valid = true;
-          data.link_rssi_dbm = pkt.rssi_dbm;
-          data.link_snr_db = pkt.snr_db;
-          for (uint8_t i = 0; i < NUM_SENDERS; ++i) {
-            if (pkt.device_id_short == EXPECTED_SENDER_IDS[i]) {
-              data.short_id = pkt.device_id_short;
-              g_sender_statuses[i].last_data = data;
-              g_sender_statuses[i].last_update_ts_utc = data.ts_utc;
-              g_sender_statuses[i].has_data = true;
-              g_sender_faults_remote[i].meter_read_fail = data.err_meter_read;
-              g_sender_faults_remote[i].lora_tx_fail = data.err_lora_tx;
-              g_sender_last_error_remote[i] = data.last_error;
-              g_sender_last_error_remote_utc[i] = time_get_utc();
-              g_sender_last_error_remote_ms[i] = millis();
-              mqtt_publish_state(data);
-              if (ENABLE_HA_DISCOVERY && !g_sender_discovery_sent[i]) {
-                g_sender_discovery_sent[i] = mqtt_publish_discovery(data.device_id);
-              }
-              publish_faults_if_needed(data.device_id, g_sender_faults_remote[i], g_sender_faults_remote_published[i],
-                                       g_sender_last_error_remote[i], g_sender_last_error_remote_published[i],
-                                       g_sender_last_error_remote_utc[i], g_sender_last_error_remote_ms[i]);
-              break;
-            }
-          }
-        } else {
-          note_fault(g_receiver_faults, g_receiver_last_error, g_receiver_last_error_utc, g_receiver_last_error_ms, FaultType::Decode);
-          display_set_last_error(g_receiver_last_error, g_receiver_last_error_utc, g_receiver_last_error_ms);
-        }
-      }
-    } else if (pkt.payload_type == PayloadType::MeterBatch) {
-      String json;
       bool decode_error = false;
       uint16_t batch_id = 0;
-      if (process_batch_packet(pkt, json, decode_error, batch_id)) {
+      if (process_batch_packet(pkt, batch, decode_error, batch_id)) {
-        uint32_t rx_ts_utc = time_get_utc();
-        if (rx_ts_utc == 0) {
-          rx_ts_utc = millis() / 1000;
-        }
-        inject_batch_meta(json, pkt.rssi_dbm, pkt.snr_db, rx_ts_utc);
-        MeterData samples[METER_BATCH_MAX_SAMPLES];
-        size_t count = 0;
         int8_t sender_idx = -1;
         for (uint8_t i = 0; i < NUM_SENDERS; ++i) {
           if (pkt.device_id_short == EXPECTED_SENDER_IDS[i]) {
@@ -824,20 +976,92 @@ static void receiver_loop() {
             break;
           }
         }
+
         bool duplicate = sender_idx >= 0 && g_last_batch_id_rx[sender_idx] == batch_id;
+        send_batch_ack(batch_id, batch.n);
         if (duplicate) {
-          send_batch_ack(batch_id, pkt.device_id_short);
+          goto receiver_loop_done;
-        } else if (jsonToMeterBatch(json, samples, METER_BATCH_MAX_SAMPLES, count)) {
+        }
         if (sender_idx >= 0) {
+          g_last_batch_id_rx[sender_idx] = batch_id;
+        }
+        if (batch.n == 0) {
+          goto receiver_loop_done;
+        }
+        if (batch.n > METER_BATCH_MAX_SAMPLES) {
+          note_fault(g_receiver_faults, g_receiver_last_error, g_receiver_last_error_utc, g_receiver_last_error_ms, FaultType::Decode);
+          display_set_last_error(g_receiver_last_error, g_receiver_last_error_utc, g_receiver_last_error_ms);
+          goto receiver_loop_done;
+        }
+
+        size_t count = batch.n;
+        uint16_t short_id = pkt.device_id_short;
+        if (short_id == 0) {
+          short_id = short_id_from_sender_id(batch.sender_id);
+        }
+        uint64_t span = static_cast<uint64_t>(batch.dt_s) * static_cast<uint64_t>(count - 1);
+        if (batch.t_last < span || batch.t_last < MIN_ACCEPTED_EPOCH_UTC) {
+          note_fault(g_receiver_faults, g_receiver_last_error, g_receiver_last_error_utc, g_receiver_last_error_ms, FaultType::Decode);
+          display_set_last_error(g_receiver_last_error, g_receiver_last_error_utc, g_receiver_last_error_ms);
+          goto receiver_loop_done;
+        }
+        uint32_t t_first = batch.t_last - static_cast<uint32_t>(span);
+        if (t_first < MIN_ACCEPTED_EPOCH_UTC) {
+          note_fault(g_receiver_faults, g_receiver_last_error, g_receiver_last_error_utc, g_receiver_last_error_ms, FaultType::Decode);
+          display_set_last_error(g_receiver_last_error, g_receiver_last_error_utc, g_receiver_last_error_ms);
+          goto receiver_loop_done;
+        }
+
+        MeterData samples[METER_BATCH_MAX_SAMPLES];
+        float bat_v = batch.battery_mV > 0 ? static_cast<float>(batch.battery_mV) / 1000.0f : NAN;
+        for (size_t s = 0; s < count; ++s) {
+          MeterData &data = samples[s];
+          data = {};
+          data.short_id = short_id;
+          if (short_id != 0) {
+            snprintf(data.device_id, sizeof(data.device_id), "dd3-%04X", short_id);
+          } else {
+            snprintf(data.device_id, sizeof(data.device_id), "dd3-0000");
+          }
+          data.ts_utc = t_first + static_cast<uint32_t>(s) * batch.dt_s;
+          if (batch.schema_id == 1) {
+            data.energy_multi = true;
+            data.energy_meter_count = batch.meter_count;
+            data.energy_kwh_int[0] = batch.energy1_kwh[s];
+            data.energy_kwh_int[1] = batch.energy2_kwh[s];
+            data.energy_kwh_int[2] = batch.energy3_kwh[s];
+            data.energy_total_kwh = static_cast<float>(batch.energy1_kwh[s]);
+            data.phase_power_w[0] = 0.0f;
+            data.phase_power_w[1] = 0.0f;
+            data.phase_power_w[2] = 0.0f;
+            data.total_power_w = 0.0f;
+          } else {
+            data.energy_total_kwh = static_cast<float>(batch.energy_wh[s]) / 1000.0f;
+            data.phase_power_w[0] = static_cast<float>(batch.p1_w[s]);
+            data.phase_power_w[1] = static_cast<float>(batch.p2_w[s]);
+            data.phase_power_w[2] = static_cast<float>(batch.p3_w[s]);
+            data.total_power_w = data.phase_power_w[0] + data.phase_power_w[1] + data.phase_power_w[2];
+          }
+          data.battery_voltage_v = bat_v;
+          data.battery_percent = !isnan(bat_v) ? battery_percent_from_voltage(bat_v) : 0;
+          data.valid = true;
+          data.link_valid = true;
+          data.link_rssi_dbm = pkt.rssi_dbm;
+          data.link_snr_db = pkt.snr_db;
+          data.err_meter_read = batch.err_m;
+          data.err_decode = batch.err_d;
+          data.err_lora_tx = batch.err_tx;
+          data.last_error = static_cast<FaultType>(batch.err_last);
+          data.rx_reject_reason = batch.err_rx_reject;
+          sd_logger_log_sample(data, (s + 1 == count) && data.last_error != FaultType::None);
+        }
+
+        if (sender_idx >= 0) {
+          g_sender_statuses[sender_idx].last_acked_batch_id = batch_id;
           web_server_set_last_batch(static_cast<uint8_t>(sender_idx), samples, count);
           for (size_t s = 0; s < count; ++s) {
-              samples[s].link_valid = true;
-              samples[s].link_rssi_dbm = pkt.rssi_dbm;
-              samples[s].link_snr_db = pkt.snr_db;
-              samples[s].short_id = pkt.device_id_short;
             mqtt_publish_state(samples[s]);
           }
-            if (count > 0) {
           g_sender_statuses[sender_idx].last_data = samples[count - 1];
           g_sender_statuses[sender_idx].last_update_ts_utc = samples[count - 1].ts_utc;
           g_sender_statuses[sender_idx].has_data = true;
@@ -853,13 +1077,6 @@ static void receiver_loop() {
                                    g_sender_last_error_remote[sender_idx], g_sender_last_error_remote_published[sender_idx],
                                    g_sender_last_error_remote_utc[sender_idx], g_sender_last_error_remote_ms[sender_idx]);
         }
-            g_last_batch_id_rx[sender_idx] = batch_id;
-            send_batch_ack(batch_id, pkt.device_id_short);
-          }
-        } else {
-          note_fault(g_receiver_faults, g_receiver_last_error, g_receiver_last_error_utc, g_receiver_last_error_ms, FaultType::Decode);
-          display_set_last_error(g_receiver_last_error, g_receiver_last_error_utc, g_receiver_last_error_ms);
-        }
       } else if (decode_error) {
         note_fault(g_receiver_faults, g_receiver_last_error, g_receiver_last_error_utc, g_receiver_last_error_ms, FaultType::Decode);
         display_set_last_error(g_receiver_last_error, g_receiver_last_error_utc, g_receiver_last_error_ms);
@@ -867,18 +1084,7 @@ static void receiver_loop() {
     }
   }
 
-  uint32_t interval_sec = TIME_SYNC_INTERVAL_SEC;
+receiver_loop_done:
-  if (time_rtc_present() && millis() - g_boot_ms >= TIME_SYNC_FAST_WINDOW_MS) {
-    interval_sec = TIME_SYNC_SLOW_INTERVAL_SEC;
-  }
-  if (!g_ap_mode && millis() - g_last_timesync_ms > interval_sec * 1000UL) {
-    g_last_timesync_ms = millis();
-    if (!time_send_timesync(g_short_id)) {
-      note_fault(g_receiver_faults, g_receiver_last_error, g_receiver_last_error_utc, g_receiver_last_error_ms, FaultType::LoraTx);
-      display_set_last_error(g_receiver_last_error, g_receiver_last_error_utc, g_receiver_last_error_ms);
-    }
-  }
-
   mqtt_loop();
   web_server_loop();
   if (ENABLE_HA_DISCOVERY && !g_receiver_discovery_sent) {

src/meter_driver.cpp

@@ -4,11 +4,31 @@
 #include <stdlib.h>
 #include <string.h>
 
-static constexpr uint32_t METER_READ_TIMEOUT_MS = 2000;
+static constexpr uint32_t METER_FRAME_TIMEOUT_MS = 1500;
+static constexpr size_t METER_FRAME_MAX = 512;
 
-void meter_init() {
+enum class MeterRxState : uint8_t {
-  Serial2.begin(9600, SERIAL_7E1, PIN_METER_RX, -1);
+  WaitStart = 0,
-}
+  InFrame = 1
+};
+
+struct MeterPort {
+  HardwareSerial *serial;
+  MeterRxState state;
+  char frame_buf[METER_FRAME_MAX + 1];
+  size_t frame_len;
+  uint32_t last_rx_ms;
+  uint32_t bytes_rx;
+  uint32_t frames_ok;
+  uint32_t frames_parse_fail;
+  uint32_t rx_overflow;
+  uint32_t rx_timeout;
+  uint32_t last_energy_kwh;
+  bool has_energy;
+};
+
+static MeterPort g_ports[METER_COUNT] = {};
+static uint32_t g_last_log_ms = 0;
 
 static bool parse_obis_ascii_value(const char *line, const char *obis, float &out_value) {
   const char *p = strstr(line, obis);
@@ -45,121 +65,142 @@ static bool parse_obis_ascii_value(const char *line, const char *obis, float &ou
   return true;
 }
 
-static bool parse_obis_ascii_unit_scale(const char *line, const char *obis, float &value) {
+static bool parse_energy_kwh_floor(const char *frame, size_t len, uint32_t &out_kwh) {
-  const char *p = strstr(line, obis);
-  if (!p) {
-    return false;
-  }
-  const char *asterisk = strchr(p, '*');
-  if (!asterisk) {
-    return false;
-  }
-  const char *end = strchr(asterisk, ')');
-  if (!end) {
-    return false;
-  }
-  char unit_buf[8];
-  size_t ulen = 0;
-  for (const char *c = asterisk + 1; c < end && ulen + 1 < sizeof(unit_buf); ++c) {
-    if (*c == ' ') {
-      continue;
-    }
-    unit_buf[ulen++] = *c;
-  }
-  unit_buf[ulen] = '\0';
-  if (ulen == 0) {
-    return false;
-  }
-  if (strcmp(unit_buf, "Wh") == 0) {
-    value *= 0.001f;
-    return true;
-  }
-  return false;
-}
-
-static bool meter_read_ascii(MeterData &data) {
-  const uint32_t start_ms = millis();
-  bool in_telegram = false;
-  bool got_any = false;
-
-  bool energy_ok = false;
-  bool total_p_ok = false;
-  bool p1_ok = false;
-  bool p2_ok = false;
-  bool p3_ok = false;
   char line[128];
   size_t line_len = 0;
-
+  for (size_t i = 0; i < len; ++i) {
-  while (millis() - start_ms < METER_READ_TIMEOUT_MS) {
+    char c = frame[i];
-    while (Serial2.available()) {
-      char c = static_cast<char>(Serial2.read());
-      if (!in_telegram) {
-        if (c == '/') {
-          in_telegram = true;
-          line_len = 0;
-          line[line_len++] = c;
-        }
-        continue;
-      }
-
     if (c == '\r') {
       continue;
     }
-      if (c == '\n') {
+    if (c == '\n' || c == '!') {
       line[line_len] = '\0';
-        if (line[0] == '!') {
-          return got_any;
-        }
-
       float value = NAN;
-        if (parse_obis_ascii_value(line, "1-0:1.8.0", value)) {
+      if (parse_obis_ascii_value(line, "1-0:1.8.0", value) && !isnan(value) && value >= 0.0f) {
-          parse_obis_ascii_unit_scale(line, "1-0:1.8.0", value);
+        out_kwh = static_cast<uint32_t>(floorf(value));
-          data.energy_total_kwh = value;
+        return true;
-          energy_ok = true;
-          got_any = true;
       }
-        if (parse_obis_ascii_value(line, "1-0:16.7.0", value)) {
-          data.total_power_w = value;
-          total_p_ok = true;
-          got_any = true;
-        }
-        if (parse_obis_ascii_value(line, "1-0:36.7.0", value)) {
-          data.phase_power_w[0] = value;
-          p1_ok = true;
-          got_any = true;
-        }
-        if (parse_obis_ascii_value(line, "1-0:56.7.0", value)) {
-          data.phase_power_w[1] = value;
-          p2_ok = true;
-          got_any = true;
-        }
-        if (parse_obis_ascii_value(line, "1-0:76.7.0", value)) {
-          data.phase_power_w[2] = value;
-          p3_ok = true;
-          got_any = true;
-        }
-
       line_len = 0;
+      if (c == '!') {
+        break;
+      }
       continue;
     }
     if (line_len + 1 < sizeof(line)) {
       line[line_len++] = c;
     }
   }
-    delay(5);
+  return false;
+}
+
+static void meter_debug_log() {
+  if (!SERIAL_DEBUG_MODE) {
+    return;
+  }
+  uint32_t now_ms = millis();
+  if (now_ms - g_last_log_ms < 60000) {
+    return;
+  }
+  g_last_log_ms = now_ms;
+  for (uint8_t i = 0; i < METER_COUNT; ++i) {
+    const MeterPort &p = g_ports[i];
+    Serial.printf("meter%u: ok=%lu parse_fail=%lu overflow=%lu timeout=%lu bytes=%lu e=%lu valid=%u\n",
+                  static_cast<unsigned>(i + 1),
+                  static_cast<unsigned long>(p.frames_ok),
+                  static_cast<unsigned long>(p.frames_parse_fail),
+                  static_cast<unsigned long>(p.rx_overflow),
+                  static_cast<unsigned long>(p.rx_timeout),
+                  static_cast<unsigned long>(p.bytes_rx),
+                  static_cast<unsigned long>(p.last_energy_kwh),
+                  p.has_energy ? 1 : 0);
+  }
+}
+
+void meter_init() {
+  g_ports[0].serial = &Serial2;
+  g_ports[0].serial->begin(9600, SERIAL_7E1, PIN_METER1_RX, -1);
+  g_ports[0].state = MeterRxState::WaitStart;
+
+  if (METER_COUNT >= 2) {
+    g_ports[1].serial = &Serial1;
+    g_ports[1].serial->begin(9600, SERIAL_7E1, PIN_METER2_RX, -1);
+    g_ports[1].state = MeterRxState::WaitStart;
   }
 
-  data.valid = energy_ok || total_p_ok || p1_ok || p2_ok || p3_ok;
+  if (METER_COUNT >= 3) {
-  return data.valid;
+    g_ports[2].serial = &Serial;
+    g_ports[2].serial->begin(9600, SERIAL_7E1, PIN_METER3_RX, -1);
+    g_ports[2].state = MeterRxState::WaitStart;
+  }
 }
 
-bool meter_read(MeterData &data) {
+static void meter_poll_port(MeterPort &port) {
-  data.energy_total_kwh = NAN;
+  if (!port.serial) {
-  data.total_power_w = NAN;
+    return;
-  data.phase_power_w[0] = NAN;
+  }
-  data.phase_power_w[1] = NAN;
+  uint32_t now_ms = millis();
-  data.phase_power_w[2] = NAN;
+  if (port.state == MeterRxState::InFrame && (now_ms - port.last_rx_ms > METER_FRAME_TIMEOUT_MS)) {
-  data.valid = false;
+    port.rx_timeout++;
+    port.state = MeterRxState::WaitStart;
+    port.frame_len = 0;
+  }
 
-  return meter_read_ascii(data);
+  while (port.serial->available()) {
+    char c = static_cast<char>(port.serial->read());
+    port.bytes_rx++;
+    port.last_rx_ms = now_ms;
+
+    if (port.state == MeterRxState::WaitStart) {
+      if (c == '/') {
+        port.state = MeterRxState::InFrame;
+        port.frame_len = 0;
+        port.frame_buf[port.frame_len++] = c;
+      }
+      continue;
+    }
+
+    if (port.frame_len + 1 >= sizeof(port.frame_buf)) {
+      port.rx_overflow++;
+      port.state = MeterRxState::WaitStart;
+      port.frame_len = 0;
+      continue;
+    }
+
+    port.frame_buf[port.frame_len++] = c;
+    if (c == '!') {
+      port.frame_buf[port.frame_len] = '\0';
+      uint32_t energy_kwh = 0;
+      if (parse_energy_kwh_floor(port.frame_buf, port.frame_len, energy_kwh)) {
+        port.last_energy_kwh = energy_kwh;
+        port.has_energy = true;
+        port.frames_ok++;
+      } else {
+        port.frames_parse_fail++;
+      }
+      port.state = MeterRxState::WaitStart;
+      port.frame_len = 0;
+    }
+  }
+}
+
+void meter_poll() {
+  for (uint8_t i = 0; i < METER_COUNT; ++i) {
+    meter_poll_port(g_ports[i]);
+  }
+  meter_debug_log();
+}
+
+uint8_t meter_count() {
+  return METER_COUNT;
+}
+
+bool meter_get_last_energy_kwh(uint8_t meter_idx, uint32_t &out_energy_kwh) {
+  if (meter_idx >= METER_COUNT) {
+    return false;
+  }
+  if (!g_ports[meter_idx].has_energy) {
+    return false;
+  }
+  out_energy_kwh = g_ports[meter_idx].last_energy_kwh;
+  return true;
 }

src/mqtt_client.cpp

@@ -10,6 +10,19 @@ static PubSubClient mqtt_client(wifi_client);
 static WifiMqttConfig g_cfg;
 static String g_client_id;
 
+static const char *fault_text(FaultType fault) {
+  switch (fault) {
+    case FaultType::MeterRead:
+      return "meter";
+    case FaultType::Decode:
+      return "decode";
+    case FaultType::LoraTx:
+      return "loratx";
+    default:
+      return "none";
+  }
+}
+
 void mqtt_init(const WifiMqttConfig &config, const char *device_id) {
   g_cfg = config;
   mqtt_client.setServer(config.mqtt_host.c_str(), config.mqtt_port);
@@ -66,10 +79,9 @@ bool mqtt_publish_faults(const char *device_id, const FaultCounters &counters, F
   doc["err_m"] = counters.meter_read_fail;
   doc["err_d"] = counters.decode_fail;
   doc["err_tx"] = counters.lora_tx_fail;
-  if (last_error != FaultType::None) {
   doc["err_last"] = static_cast<uint8_t>(last_error);
-    doc["err_last_age"] = last_error_age_sec;
+  doc["err_last_text"] = fault_text(last_error);
-  }
+  doc["err_last_age"] = last_error != FaultType::None ? last_error_age_sec : 0;
 
   String payload;
   size_t len = serializeJson(doc, payload);
@@ -138,6 +150,8 @@ bool mqtt_publish_discovery(const char *device_id) {
   ok = ok && publish_discovery_sensor(device_id, "err_m", "Meter Read Errors", "count", "", faults_topic.c_str(), "{{ value_json.err_m }}");
   ok = ok && publish_discovery_sensor(device_id, "err_d", "Decode Errors", "count", "", faults_topic.c_str(), "{{ value_json.err_d }}");
   ok = ok && publish_discovery_sensor(device_id, "err_tx", "LoRa TX Errors", "count", "", faults_topic.c_str(), "{{ value_json.err_tx }}");
+  ok = ok && publish_discovery_sensor(device_id, "err_last", "Last Error Code", "", "", faults_topic.c_str(), "{{ value_json.err_last }}");
+  ok = ok && publish_discovery_sensor(device_id, "err_last_text", "Last Error", "", "", faults_topic.c_str(), "{{ value_json.err_last_text }}");
   ok = ok && publish_discovery_sensor(device_id, "err_last_age", "Last Error Age", "s", "", faults_topic.c_str(), "{{ value_json.err_last_age }}");
   return ok;
 }

src/payload_codec.cpp

@@ -0,0 +1,406 @@
+#include "payload_codec.h"
+#include <limits.h>
+
+static constexpr uint16_t kMagic = 0xDDB3;
+static constexpr uint8_t kSchema = 2;
+static constexpr uint8_t kFlags = 0x01;
+static constexpr size_t kMaxSamples = 30;
+static constexpr uint8_t kPayloadSchemaLegacy = 0;
+static constexpr uint8_t kPayloadSchemaEnergyMulti = 1;
+
+static void write_u16_le(uint8_t *dst, uint16_t value) {
+  dst[0] = static_cast<uint8_t>(value & 0xFF);
+  dst[1] = static_cast<uint8_t>((value >> 8) & 0xFF);
+}
+
+static void write_u32_le(uint8_t *dst, uint32_t value) {
+  dst[0] = static_cast<uint8_t>(value & 0xFF);
+  dst[1] = static_cast<uint8_t>((value >> 8) & 0xFF);
+  dst[2] = static_cast<uint8_t>((value >> 16) & 0xFF);
+  dst[3] = static_cast<uint8_t>((value >> 24) & 0xFF);
+}
+
+static uint16_t read_u16_le(const uint8_t *src) {
+  return static_cast<uint16_t>(src[0]) | (static_cast<uint16_t>(src[1]) << 8);
+}
+
+static uint32_t read_u32_le(const uint8_t *src) {
+  return static_cast<uint32_t>(src[0]) |
+         (static_cast<uint32_t>(src[1]) << 8) |
+         (static_cast<uint32_t>(src[2]) << 16) |
+         (static_cast<uint32_t>(src[3]) << 24);
+}
+
+size_t uleb128_encode(uint32_t v, uint8_t *out, size_t cap) {
+  size_t i = 0;
+  do {
+    if (i >= cap) {
+      return 0;
+    }
+    uint8_t byte = static_cast<uint8_t>(v & 0x7F);
+    v >>= 7;
+    if (v != 0) {
+      byte |= 0x80;
+    }
+    out[i++] = byte;
+  } while (v != 0);
+  return i;
+}
+
+bool uleb128_decode(const uint8_t *in, size_t len, size_t *pos, uint32_t *v) {
+  if (!in || !pos || !v) {
+    return false;
+  }
+  uint32_t result = 0;
+  uint8_t shift = 0;
+  size_t p = *pos;
+  for (uint8_t i = 0; i < 5; ++i) {
+    if (p >= len) {
+      return false;
+    }
+    uint8_t byte = in[p++];
+    if (i == 4 && (byte & 0xF0) != 0) {
+      return false;
+    }
+    result |= static_cast<uint32_t>(byte & 0x7F) << shift;
+    if ((byte & 0x80) == 0) {
+      *pos = p;
+      *v = result;
+      return true;
+    }
+    shift = static_cast<uint8_t>(shift + 7);
+  }
+  return false;
+}
+
+uint32_t zigzag32(int32_t x) {
+  return (static_cast<uint32_t>(x) << 1) ^ static_cast<uint32_t>(x >> 31);
+}
+
+int32_t unzigzag32(uint32_t u) {
+  return static_cast<int32_t>((u >> 1) ^ (static_cast<uint32_t>(-static_cast<int32_t>(u & 1))));
+}
+
+size_t svarint_encode(int32_t x, uint8_t *out, size_t cap) {
+  uint32_t zz = zigzag32(x);
+  return uleb128_encode(zz, out, cap);
+}
+
+bool svarint_decode(const uint8_t *in, size_t len, size_t *pos, int32_t *x) {
+  uint32_t u = 0;
+  if (!uleb128_decode(in, len, pos, &u)) {
+    return false;
+  }
+  *x = unzigzag32(u);
+  return true;
+}
+
+static bool ensure_capacity(size_t needed, size_t cap, size_t pos) {
+  return pos + needed <= cap;
+}
+
+bool encode_batch(const BatchInput &in, uint8_t *out, size_t out_cap, size_t *out_len) {
+  if (!out || !out_len) {
+    return false;
+  }
+  if (in.n > kMaxSamples) {
+    return false;
+  }
+  if (in.dt_s == 0) {
+    return false;
+  }
+  size_t pos = 0;
+  if (!ensure_capacity(23, out_cap, pos)) {
+    return false;
+  }
+  write_u16_le(&out[pos], kMagic);
+  pos += 2;
+  out[pos++] = kSchema;
+  out[pos++] = kFlags;
+  out[pos++] = in.schema_id;
+  write_u16_le(&out[pos], in.sender_id);
+  pos += 2;
+  write_u16_le(&out[pos], in.batch_id);
+  pos += 2;
+  write_u32_le(&out[pos], in.t_last);
+  pos += 4;
+  out[pos++] = in.dt_s;
+  out[pos++] = in.n;
+  write_u16_le(&out[pos], in.battery_mV);
+  pos += 2;
+  out[pos++] = in.err_m;
+  out[pos++] = in.err_d;
+  out[pos++] = in.err_tx;
+  out[pos++] = in.err_last;
+  out[pos++] = in.err_rx_reject;
+  out[pos++] = in.meter_count;
+
+  if (in.n == 0) {
+    *out_len = pos;
+    return true;
+  }
+
+  if (in.schema_id == kPayloadSchemaEnergyMulti) {
+    if (in.meter_count == 0 || in.meter_count > 3) {
+      return false;
+    }
+    if (!ensure_capacity(static_cast<size_t>(in.n) * 12, out_cap, pos)) {
+      return false;
+    }
+    for (uint8_t i = 0; i < in.n; ++i) {
+      write_u32_le(&out[pos], in.energy1_kwh[i]);
+      pos += 4;
+      write_u32_le(&out[pos], in.energy2_kwh[i]);
+      pos += 4;
+      write_u32_le(&out[pos], in.energy3_kwh[i]);
+      pos += 4;
+    }
+    *out_len = pos;
+    return true;
+  }
+
+  if (!ensure_capacity(4, out_cap, pos)) {
+    return false;
+  }
+  write_u32_le(&out[pos], in.energy_wh[0]);
+  pos += 4;
+  for (uint8_t i = 1; i < in.n; ++i) {
+    if (in.energy_wh[i] < in.energy_wh[i - 1]) {
+      return false;
+    }
+    uint32_t delta = in.energy_wh[i] - in.energy_wh[i - 1];
+    size_t wrote = uleb128_encode(delta, &out[pos], out_cap - pos);
+    if (wrote == 0) {
+      return false;
+    }
+    pos += wrote;
+  }
+
+  auto encode_phase = [&](const int16_t *phase) -> bool {
+    if (!ensure_capacity(2, out_cap, pos)) {
+      return false;
+    }
+    write_u16_le(&out[pos], static_cast<uint16_t>(phase[0]));
+    pos += 2;
+    for (uint8_t i = 1; i < in.n; ++i) {
+      int32_t delta = static_cast<int32_t>(phase[i]) - static_cast<int32_t>(phase[i - 1]);
+      size_t wrote = svarint_encode(delta, &out[pos], out_cap - pos);
+      if (wrote == 0) {
+        return false;
+      }
+      pos += wrote;
+    }
+    return true;
+  };
+
+  if (!encode_phase(in.p1_w)) {
+    return false;
+  }
+  if (!encode_phase(in.p2_w)) {
+    return false;
+  }
+  if (!encode_phase(in.p3_w)) {
+    return false;
+  }
+
+  *out_len = pos;
+  return true;
+}
+
+bool decode_batch(const uint8_t *buf, size_t len, BatchInput *out) {
+  if (!buf || !out) {
+    return false;
+  }
+  size_t pos = 0;
+  if (len < 23) {
+    return false;
+  }
+  uint16_t magic = read_u16_le(&buf[pos]);
+  pos += 2;
+  uint8_t schema = buf[pos++];
+  uint8_t flags = buf[pos++];
+  if (magic != kMagic || schema != kSchema || (flags & 0x01) == 0) {
+    return false;
+  }
+  out->schema_id = buf[pos++];
+  out->sender_id = read_u16_le(&buf[pos]);
+  pos += 2;
+  out->batch_id = read_u16_le(&buf[pos]);
+  pos += 2;
+  out->t_last = read_u32_le(&buf[pos]);
+  pos += 4;
+  out->dt_s = buf[pos++];
+  out->n = buf[pos++];
+  out->battery_mV = read_u16_le(&buf[pos]);
+  pos += 2;
+  out->err_m = buf[pos++];
+  out->err_d = buf[pos++];
+  out->err_tx = buf[pos++];
+  out->err_last = buf[pos++];
+  out->err_rx_reject = buf[pos++];
+  out->meter_count = buf[pos++];
+
+  if (out->n > kMaxSamples || out->dt_s == 0) {
+    return false;
+  }
+  if (out->n == 0) {
+    for (uint8_t i = 0; i < kMaxSamples; ++i) {
+      out->energy_wh[i] = 0;
+      out->p1_w[i] = 0;
+      out->p2_w[i] = 0;
+      out->p3_w[i] = 0;
+    }
+    return pos == len;
+  }
+  if (out->schema_id == kPayloadSchemaEnergyMulti) {
+    if (out->meter_count == 0 || out->meter_count > 3) {
+      return false;
+    }
+    if (pos + static_cast<size_t>(out->n) * 12 > len) {
+      return false;
+    }
+    for (uint8_t i = 0; i < out->n; ++i) {
+      out->energy1_kwh[i] = read_u32_le(&buf[pos]);
+      pos += 4;
+      out->energy2_kwh[i] = read_u32_le(&buf[pos]);
+      pos += 4;
+      out->energy3_kwh[i] = read_u32_le(&buf[pos]);
+      pos += 4;
+    }
+    for (uint8_t i = out->n; i < kMaxSamples; ++i) {
+      out->energy1_kwh[i] = 0;
+      out->energy2_kwh[i] = 0;
+      out->energy3_kwh[i] = 0;
+    }
+    return pos == len;
+  }
+
+  if (pos + 4 > len) {
+    return false;
+  }
+  out->energy_wh[0] = read_u32_le(&buf[pos]);
+  pos += 4;
+  for (uint8_t i = 1; i < out->n; ++i) {
+    uint32_t delta = 0;
+    if (!uleb128_decode(buf, len, &pos, &delta)) {
+      return false;
+    }
+    uint64_t sum = static_cast<uint64_t>(out->energy_wh[i - 1]) + static_cast<uint64_t>(delta);
+    if (sum > UINT32_MAX) {
+      return false;
+    }
+    out->energy_wh[i] = static_cast<uint32_t>(sum);
+  }
+
+  auto decode_phase = [&](int16_t *phase) -> bool {
+    if (pos + 2 > len) {
+      return false;
+    }
+    phase[0] = static_cast<int16_t>(read_u16_le(&buf[pos]));
+    pos += 2;
+    int32_t prev = static_cast<int32_t>(phase[0]);
+    for (uint8_t i = 1; i < out->n; ++i) {
+      int32_t delta = 0;
+      if (!svarint_decode(buf, len, &pos, &delta)) {
+        return false;
+      }
+      int32_t value = prev + delta;
+      if (value < INT16_MIN || value > INT16_MAX) {
+        return false;
+      }
+      phase[i] = static_cast<int16_t>(value);
+      prev = value;
+    }
+    return true;
+  };
+
+  if (!decode_phase(out->p1_w)) {
+    return false;
+  }
+  if (!decode_phase(out->p2_w)) {
+    return false;
+  }
+  if (!decode_phase(out->p3_w)) {
+    return false;
+  }
+
+  for (uint8_t i = out->n; i < kMaxSamples; ++i) {
+    out->energy_wh[i] = 0;
+    out->p1_w[i] = 0;
+    out->p2_w[i] = 0;
+    out->p3_w[i] = 0;
+  }
+
+  return pos == len;
+}
+
+#ifdef PAYLOAD_CODEC_TEST
+bool payload_codec_self_test() {
+  BatchInput in = {};
+  in.schema_id = kPayloadSchemaLegacy;
+  in.sender_id = 1;
+  in.batch_id = 42;
+  in.t_last = 1700000000;
+  in.dt_s = 1;
+  in.n = 5;
+  in.battery_mV = 3750;
+  in.err_m = 2;
+  in.err_d = 1;
+  in.err_tx = 3;
+  in.err_last = 2;
+  in.err_rx_reject = 1;
+  in.meter_count = 0;
+  in.energy_wh[0] = 100000;
+  in.energy_wh[1] = 100001;
+  in.energy_wh[2] = 100050;
+  in.energy_wh[3] = 100050;
+  in.energy_wh[4] = 100200;
+  in.p1_w[0] = -120;
+  in.p1_w[1] = -90;
+  in.p1_w[2] = 1910;
+  in.p1_w[3] = -90;
+  in.p1_w[4] = 500;
+  in.p2_w[0] = 50;
+  in.p2_w[1] = -1950;
+  in.p2_w[2] = 60;
+  in.p2_w[3] = 2060;
+  in.p2_w[4] = -10;
+  in.p3_w[0] = 0;
+  in.p3_w[1] = 10;
+  in.p3_w[2] = -1990;
+  in.p3_w[3] = 10;
+  in.p3_w[4] = 20;
+
+  uint8_t buf[256];
+  size_t len = 0;
+  if (!encode_batch(in, buf, sizeof(buf), &len)) {
+    Serial.println("payload_codec_self_test: encode failed");
+    return false;
+  }
+
+  BatchInput out = {};
+  if (!decode_batch(buf, len, &out)) {
+    Serial.println("payload_codec_self_test: decode failed");
+    return false;
+  }
+
+  if (out.sender_id != in.sender_id || out.batch_id != in.batch_id || out.t_last != in.t_last ||
+      out.dt_s != in.dt_s || out.n != in.n || out.battery_mV != in.battery_mV ||
+      out.err_m != in.err_m || out.err_d != in.err_d || out.err_tx != in.err_tx || out.err_last != in.err_last ||
+      out.err_rx_reject != in.err_rx_reject) {
+    Serial.println("payload_codec_self_test: header mismatch");
+    return false;
+  }
+
+  for (uint8_t i = 0; i < in.n; ++i) {
+    if (out.energy_wh[i] != in.energy_wh[i] || out.p1_w[i] != in.p1_w[i] || out.p2_w[i] != in.p2_w[i] ||
+        out.p3_w[i] != in.p3_w[i]) {
+      Serial.println("payload_codec_self_test: sample mismatch");
+      return false;
+    }
+  }
+
+  Serial.printf("payload_codec_self_test: ok len=%u\n", static_cast<unsigned>(len));
+  return true;
+}
+#endif

src/payload_codec.h

@@ -0,0 +1,42 @@
+#pragma once
+
+#include <Arduino.h>
+
+struct BatchInput {
+  uint8_t schema_id;
+  uint16_t sender_id;
+  uint16_t batch_id;
+  uint32_t t_last;
+  uint8_t dt_s;
+  uint8_t n;
+  uint8_t meter_count;
+  uint16_t battery_mV;
+  uint8_t err_m;
+  uint8_t err_d;
+  uint8_t err_tx;
+  uint8_t err_last;
+  uint8_t err_rx_reject;
+  uint32_t energy1_kwh[30];
+  uint32_t energy2_kwh[30];
+  uint32_t energy3_kwh[30];
+  uint32_t energy_wh[30];
+  int16_t p1_w[30];
+  int16_t p2_w[30];
+  int16_t p3_w[30];
+};
+
+bool encode_batch(const BatchInput &in, uint8_t *out, size_t out_cap, size_t *out_len);
+bool decode_batch(const uint8_t *buf, size_t len, BatchInput *out);
+
+size_t uleb128_encode(uint32_t v, uint8_t *out, size_t cap);
+bool uleb128_decode(const uint8_t *in, size_t len, size_t *pos, uint32_t *v);
+
+uint32_t zigzag32(int32_t x);
+int32_t unzigzag32(uint32_t u);
+
+size_t svarint_encode(int32_t x, uint8_t *out, size_t cap);
+bool svarint_decode(const uint8_t *in, size_t len, size_t *pos, int32_t *x);
+
+#ifdef PAYLOAD_CODEC_TEST
+bool payload_codec_self_test();
+#endif

src/power_manager.cpp

@@ -6,11 +6,13 @@
 #include <esp_sleep.h>
 
 static constexpr float BATTERY_DIVIDER = 2.0f;
-static constexpr float BATTERY_CAL = 1.0f;
 static constexpr float ADC_REF_V = 3.3f;
 
 void power_sender_init() {
+  setCpuFrequencyMhz(80);
+  WiFi.mode(WIFI_OFF);
   esp_wifi_stop();
+  esp_wifi_deinit();
   btStop();
   analogReadResolution(12);
   pinMode(PIN_BAT_ADC, INPUT);
@@ -22,22 +24,79 @@ void power_receiver_init() {
   pinMode(PIN_BAT_ADC, INPUT);
 }
 
-void read_battery(MeterData &data) {
+void power_configure_unused_pins_sender() {
-  const int samples = 8;
+  // Board-specific: only touch pins that are known unused and safe on TTGO LoRa32 v1.6.1
-  uint32_t sum = 0;
+  const uint8_t pins[] = {32, 33};
-  for (int i = 0; i < samples; ++i) {
+  for (uint8_t pin : pins) {
-    sum += analogRead(PIN_BAT_ADC);
+    pinMode(pin, INPUT_PULLDOWN);
-    delay(5);
   }
-  float avg = static_cast<float>(sum) / samples;
+}
+
+void read_battery(MeterData &data) {
+  uint32_t sum = 0;
+  uint16_t samples[5] = {};
+  for (uint8_t i = 0; i < 5; ++i) {
+    samples[i] = analogRead(PIN_BAT_ADC);
+    sum += samples[i];
+  }
+  float avg = static_cast<float>(sum) / 5.0f;
   float v = (avg / 4095.0f) * ADC_REF_V * BATTERY_DIVIDER * BATTERY_CAL;
+  if (SERIAL_DEBUG_MODE) {
+    Serial.printf("bat_adc: %u %u %u %u %u avg=%.1f v=%.3f\n",
+                  samples[0], samples[1], samples[2], samples[3], samples[4],
+                  static_cast<double>(avg), static_cast<double>(v));
+  }
 
   data.battery_voltage_v = v;
   data.battery_percent = battery_percent_from_voltage(v);
 }
 
 uint8_t battery_percent_from_voltage(float voltage_v) {
-  float pct = (voltage_v - 3.0f) / (4.2f - 3.0f) * 100.0f;
+  if (isnan(voltage_v)) {
+    return 0;
+  }
+  struct LutPoint {
+    float v;
+    uint8_t pct;
+  };
+  static const LutPoint kCurve[] = {
+      {4.20f, 100},
+      {4.15f, 95},
+      {4.11f, 90},
+      {4.08f, 85},
+      {4.02f, 80},
+      {3.98f, 75},
+      {3.95f, 70},
+      {3.91f, 60},
+      {3.87f, 50},
+      {3.85f, 45},
+      {3.84f, 40},
+      {3.82f, 35},
+      {3.80f, 30},
+      {3.77f, 25},
+      {3.75f, 20},
+      {3.73f, 15},
+      {3.70f, 10},
+      {3.65f, 5},
+      {3.60f, 2},
+      {2.90f, 0},
+  };
+  if (voltage_v >= kCurve[0].v) {
+    return kCurve[0].pct;
+  }
+  if (voltage_v <= kCurve[sizeof(kCurve) / sizeof(kCurve[0]) - 1].v) {
+    return 0;
+  }
+  for (size_t i = 0; i + 1 < sizeof(kCurve) / sizeof(kCurve[0]); ++i) {
+    const LutPoint &hi = kCurve[i];
+    const LutPoint &lo = kCurve[i + 1];
+    if (voltage_v <= hi.v && voltage_v >= lo.v) {
+      float span = hi.v - lo.v;
+      if (span <= 0.0f) {
+        return lo.pct;
+      }
+      float t = (voltage_v - lo.v) / span;
+      float pct = lo.pct + t * (hi.pct - lo.pct);
       if (pct < 0.0f) {
         pct = 0.0f;
       }
@@ -45,6 +104,9 @@ uint8_t battery_percent_from_voltage(float voltage_v) {
         pct = 100.0f;
       }
       return static_cast<uint8_t>(pct + 0.5f);
+    }
+  }
+  return 0;
 }
 
 void light_sleep_ms(uint32_t ms) {

src/rtc_ds3231.cpp

@@ -1,122 +0,0 @@
-#include "rtc_ds3231.h"
-#include "config.h"
-#include <Wire.h>
-#include <time.h>
-
-static constexpr uint8_t DS3231_ADDR = 0x68;
-
-static uint8_t bcd_to_dec(uint8_t val) {
-  return static_cast<uint8_t>((val >> 4) * 10 + (val & 0x0F));
-}
-
-static uint8_t dec_to_bcd(uint8_t val) {
-  return static_cast<uint8_t>(((val / 10) << 4) | (val % 10));
-}
-
-static time_t timegm_fallback(struct tm *tm_utc) {
-  if (!tm_utc) {
-    return static_cast<time_t>(-1);
-  }
-  char *old_tz = getenv("TZ");
-  setenv("TZ", "UTC0", 1);
-  tzset();
-  time_t t = mktime(tm_utc);
-  if (old_tz) {
-    setenv("TZ", old_tz, 1);
-  } else {
-    unsetenv("TZ");
-  }
-  tzset();
-  return t;
-}
-
-static bool read_registers(uint8_t start_reg, uint8_t *out, size_t len) {
-  if (!out || len == 0) {
-    return false;
-  }
-  Wire.beginTransmission(DS3231_ADDR);
-  Wire.write(start_reg);
-  if (Wire.endTransmission(false) != 0) {
-    return false;
-  }
-  size_t read = Wire.requestFrom(DS3231_ADDR, static_cast<uint8_t>(len));
-  if (read != len) {
-    return false;
-  }
-  for (size_t i = 0; i < len; ++i) {
-    out[i] = Wire.read();
-  }
-  return true;
-}
-
-static bool write_registers(uint8_t start_reg, const uint8_t *data, size_t len) {
-  if (!data || len == 0) {
-    return false;
-  }
-  Wire.beginTransmission(DS3231_ADDR);
-  Wire.write(start_reg);
-  for (size_t i = 0; i < len; ++i) {
-    Wire.write(data[i]);
-  }
-  return Wire.endTransmission() == 0;
-}
-
-bool rtc_ds3231_init() {
-  Wire.begin(PIN_OLED_SDA, PIN_OLED_SCL);
-  Wire.setClock(100000);
-  return rtc_ds3231_is_present();
-}
-
-bool rtc_ds3231_is_present() {
-  Wire.beginTransmission(DS3231_ADDR);
-  return Wire.endTransmission() == 0;
-}
-
-bool rtc_ds3231_read_epoch(uint32_t &epoch_utc) {
-  uint8_t regs[7] = {};
-  if (!read_registers(0x00, regs, sizeof(regs))) {
-    return false;
-  }
-
-  uint8_t sec = bcd_to_dec(regs[0] & 0x7F);
-  uint8_t min = bcd_to_dec(regs[1] & 0x7F);
-  uint8_t hour = bcd_to_dec(regs[2] & 0x3F);
-  uint8_t day = bcd_to_dec(regs[4] & 0x3F);
-  uint8_t month = bcd_to_dec(regs[5] & 0x1F);
-  uint16_t year = 2000 + bcd_to_dec(regs[6]);
-
-  struct tm tm_utc = {};
-  tm_utc.tm_sec = sec;
-  tm_utc.tm_min = min;
-  tm_utc.tm_hour = hour;
-  tm_utc.tm_mday = day;
-  tm_utc.tm_mon = month - 1;
-  tm_utc.tm_year = year - 1900;
-  tm_utc.tm_isdst = 0;
-
-  time_t t = timegm_fallback(&tm_utc);
-  if (t <= 0) {
-    return false;
-  }
-  epoch_utc = static_cast<uint32_t>(t);
-  return true;
-}
-
-bool rtc_ds3231_set_epoch(uint32_t epoch_utc) {
-  time_t t = static_cast<time_t>(epoch_utc);
-  struct tm tm_utc = {};
-  if (!gmtime_r(&t, &tm_utc)) {
-    return false;
-  }
-
-  uint8_t regs[7] = {};
-  regs[0] = dec_to_bcd(static_cast<uint8_t>(tm_utc.tm_sec));
-  regs[1] = dec_to_bcd(static_cast<uint8_t>(tm_utc.tm_min));
-  regs[2] = dec_to_bcd(static_cast<uint8_t>(tm_utc.tm_hour));
-  regs[3] = dec_to_bcd(static_cast<uint8_t>(tm_utc.tm_wday + 1));
-  regs[4] = dec_to_bcd(static_cast<uint8_t>(tm_utc.tm_mday));
-  regs[5] = dec_to_bcd(static_cast<uint8_t>(tm_utc.tm_mon + 1));
-  regs[6] = dec_to_bcd(static_cast<uint8_t>((tm_utc.tm_year + 1900) - 2000));
-
-  return write_registers(0x00, regs, sizeof(regs));
-}

src/sd_logger.cpp

@@ -0,0 +1,128 @@
+#include "sd_logger.h"
+#include "config.h"
+#include <SD.h>
+#include <SPI.h>
+#include <time.h>
+
+static bool g_sd_ready = false;
+static SPIClass *g_sd_spi = nullptr;
+
+static const char *fault_text(FaultType fault) {
+  switch (fault) {
+    case FaultType::MeterRead:
+      return "meter";
+    case FaultType::Decode:
+      return "decode";
+    case FaultType::LoraTx:
+      return "loratx";
+    default:
+      return "";
+  }
+}
+
+static bool ensure_dir(const String &path) {
+  if (SD.exists(path)) {
+    return true;
+  }
+  return SD.mkdir(path);
+}
+
+static String format_date_utc(uint32_t ts_utc) {
+  time_t t = static_cast<time_t>(ts_utc);
+  struct tm tm_utc;
+  gmtime_r(&t, &tm_utc);
+  char buf[16];
+  snprintf(buf, sizeof(buf), "%04d-%02d-%02d",
+           tm_utc.tm_year + 1900,
+           tm_utc.tm_mon + 1,
+           tm_utc.tm_mday);
+  return String(buf);
+}
+
+void sd_logger_init() {
+  if (!ENABLE_SD_LOGGING) {
+    g_sd_ready = false;
+    return;
+  }
+  if (!g_sd_spi) {
+    g_sd_spi = new SPIClass(HSPI);
+  }
+  g_sd_spi->begin(PIN_SD_SCK, PIN_SD_MISO, PIN_SD_MOSI, PIN_SD_CS);
+  g_sd_ready = SD.begin(PIN_SD_CS, *g_sd_spi);
+  if (SERIAL_DEBUG_MODE) {
+    if (g_sd_ready) {
+      uint8_t type = SD.cardType();
+      uint64_t size = SD.cardSize();
+      Serial.printf("sd: ok type=%u size=%llu\n", static_cast<unsigned>(type), static_cast<unsigned long long>(size));
+    } else {
+      Serial.println("sd: init failed");
+    }
+  }
+}
+
+bool sd_logger_is_ready() {
+  return g_sd_ready;
+}
+
+void sd_logger_log_sample(const MeterData &data, bool include_error_text) {
+  if (!g_sd_ready || data.ts_utc == 0) {
+    return;
+  }
+
+  String root_dir = "/dd3";
+  if (!ensure_dir(root_dir)) {
+    return;
+  }
+
+  String sender_dir = root_dir + "/" + String(data.device_id);
+  if (!ensure_dir(sender_dir)) {
+    return;
+  }
+
+  String filename = sender_dir + "/" + format_date_utc(data.ts_utc) + ".csv";
+  bool new_file = !SD.exists(filename);
+  File f = SD.open(filename, FILE_APPEND);
+  if (!f) {
+    return;
+  }
+
+  if (new_file) {
+    f.println("ts_utc,p_w,p1_w,p2_w,p3_w,e_kwh,bat_v,bat_pct,rssi,snr,err_m,err_d,err_tx,err_last");
+  }
+
+  f.print(data.ts_utc);
+  f.print(',');
+  f.print(data.total_power_w, 1);
+  f.print(',');
+  f.print(data.phase_power_w[0], 1);
+  f.print(',');
+  f.print(data.phase_power_w[1], 1);
+  f.print(',');
+  f.print(data.phase_power_w[2], 1);
+  f.print(',');
+  f.print(data.energy_total_kwh, 3);
+  f.print(',');
+  f.print(data.battery_voltage_v, 2);
+  f.print(',');
+  f.print(data.battery_percent);
+  f.print(',');
+  f.print(data.link_rssi_dbm);
+  f.print(',');
+  if (isnan(data.link_snr_db)) {
+    f.print("");
+  } else {
+    f.print(data.link_snr_db, 1);
+  }
+  f.print(',');
+  f.print(data.err_meter_read);
+  f.print(',');
+  f.print(data.err_decode);
+  f.print(',');
+  f.print(data.err_lora_tx);
+  f.print(',');
+  if (include_error_text && data.last_error != FaultType::None) {
+    f.print(fault_text(data.last_error));
+  }
+  f.println();
+  f.close();
+}

src/sd_logger.h

@@ -0,0 +1,7 @@
+#pragma once
+
+#include "data_model.h"
+
+void sd_logger_init();
+bool sd_logger_is_ready();
+void sd_logger_log_sample(const MeterData &data, bool include_error_text);

src/test_mode.cpp

@@ -2,9 +2,7 @@
 
 #ifdef ENABLE_TEST_MODE
 #include "config.h"
-#include "compressor.h"
 #include "lora_transport.h"
-#include "json_codec.h"
 #include "time_manager.h"
 #include "display_ui.h"
 #include "mqtt_client.h"
@@ -14,16 +12,94 @@
 
 static uint32_t g_last_test_ms = 0;
 static uint16_t g_test_code_counter = 1000;
-static uint32_t g_last_timesync_ms = 0;
+static uint16_t g_test_batch_id = 1;
+static uint16_t g_test_last_acked_batch_id = 0;
 static constexpr uint32_t TEST_SEND_INTERVAL_MS = 30000;
-static constexpr uint32_t TEST_TIMESYNC_OFFSET_MS = 15000;
 
-void test_sender_loop(uint16_t short_id, const char *device_id) {
+static void write_u16_be(uint8_t *dst, uint16_t value) {
-  LoraPacket rx = {};
+  dst[0] = static_cast<uint8_t>((value >> 8) & 0xFF);
-  if (lora_receive(rx, 0) && rx.payload_type == PayloadType::TimeSync) {
+  dst[1] = static_cast<uint8_t>(value & 0xFF);
-    time_handle_timesync_payload(rx.payload, rx.payload_len);
+}
+
+static uint16_t read_u16_be(const uint8_t *src) {
+  return static_cast<uint16_t>(src[0] << 8) | static_cast<uint16_t>(src[1]);
+}
+
+static void write_u32_be(uint8_t *dst, uint32_t value) {
+  dst[0] = static_cast<uint8_t>((value >> 24) & 0xFF);
+  dst[1] = static_cast<uint8_t>((value >> 16) & 0xFF);
+  dst[2] = static_cast<uint8_t>((value >> 8) & 0xFF);
+  dst[3] = static_cast<uint8_t>(value & 0xFF);
+}
+
+static uint32_t read_u32_be(const uint8_t *src) {
+  return (static_cast<uint32_t>(src[0]) << 24) |
+      (static_cast<uint32_t>(src[1]) << 16) |
+      (static_cast<uint32_t>(src[2]) << 8) |
+      static_cast<uint32_t>(src[3]);
+}
+
+static uint32_t ack_window_ms() {
+  uint32_t air_ms = lora_airtime_ms(lora_frame_size(LORA_ACK_DOWN_PAYLOAD_LEN));
+  uint32_t window_ms = air_ms + 300;
+  if (window_ms < 1200) {
+    window_ms = 1200;
+  }
+  if (window_ms > 4000) {
+    window_ms = 4000;
+  }
+  return window_ms;
+}
+
+static bool receive_ack_for_batch(uint16_t batch_id, uint8_t &time_valid, uint32_t &ack_epoch, int16_t &rssi_dbm, float &snr_db) {
+  LoraPacket ack_pkt = {};
+  uint32_t window_ms = ack_window_ms();
+  bool got_ack = lora_receive_window(ack_pkt, window_ms);
+  if (!got_ack) {
+    got_ack = lora_receive_window(ack_pkt, window_ms / 2);
+  }
+  if (!got_ack || ack_pkt.msg_kind != LoraMsgKind::AckDown || ack_pkt.payload_len < LORA_ACK_DOWN_PAYLOAD_LEN) {
+    return false;
   }
 
+  uint16_t ack_id = read_u16_be(&ack_pkt.payload[1]);
+  if (ack_id != batch_id) {
+    return false;
+  }
+
+  time_valid = ack_pkt.payload[0] & 0x01;
+  ack_epoch = read_u32_be(&ack_pkt.payload[3]);
+  rssi_dbm = ack_pkt.rssi_dbm;
+  snr_db = ack_pkt.snr_db;
+  return true;
+}
+
+static void send_test_ack(uint16_t self_short_id, uint16_t batch_id, uint8_t &time_valid, uint32_t &ack_epoch) {
+  ack_epoch = time_get_utc();
+  time_valid = (time_is_synced() && ack_epoch >= MIN_ACCEPTED_EPOCH_UTC) ? 1 : 0;
+  if (!time_valid) {
+    ack_epoch = 0;
+  }
+
+  LoraPacket ack = {};
+  ack.msg_kind = LoraMsgKind::AckDown;
+  ack.device_id_short = self_short_id;
+  ack.payload_len = LORA_ACK_DOWN_PAYLOAD_LEN;
+  ack.payload[0] = time_valid;
+  write_u16_be(&ack.payload[1], batch_id);
+  write_u32_be(&ack.payload[3], ack_epoch);
+
+  uint8_t repeats = ACK_REPEAT_COUNT == 0 ? 1 : ACK_REPEAT_COUNT;
+  for (uint8_t i = 0; i < repeats; ++i) {
+    lora_send(ack);
+    if (i + 1 < repeats && ACK_REPEAT_DELAY_MS > 0) {
+      delay(ACK_REPEAT_DELAY_MS);
+    }
+  }
+  lora_receive_continuous();
+}
+
+void test_sender_loop(uint16_t short_id, const char *device_id) {
   if (millis() - g_last_test_ms < TEST_SEND_INTERVAL_MS) {
     return;
   }
@@ -45,11 +121,13 @@ void test_sender_loop(uint16_t short_id, const char *device_id) {
   uint32_t now_utc = time_get_utc();
   uint32_t ts = now_utc > 0 ? now_utc : millis() / 1000;
 
-  StaticJsonDocument<128> doc;
+  StaticJsonDocument<192> doc;
   doc["id"] = device_id;
   doc["role"] = "sender";
   doc["test_code"] = code;
   doc["ts"] = ts;
+  doc["batch_id"] = g_test_batch_id;
+  doc["last_acked"] = g_test_last_acked_batch_id;
   char bat_buf[8];
   snprintf(bat_buf, sizeof(bat_buf), "%.2f", data.battery_voltage_v);
   doc["bat_v"] = serialized(bat_buf);
@@ -60,58 +138,71 @@ void test_sender_loop(uint16_t short_id, const char *device_id) {
   data.ts_utc = ts;
   display_set_last_meter(data);
 
-  uint8_t compressed[LORA_MAX_PAYLOAD];
+  if (json.length() > LORA_MAX_PAYLOAD) {
-  size_t compressed_len = 0;
-  if (!compressBuffer(reinterpret_cast<const uint8_t *>(json.c_str()), json.length(), compressed, sizeof(compressed), compressed_len)) {
     return;
   }
 
   LoraPacket pkt = {};
-  pkt.protocol_version = PROTOCOL_VERSION;
+  pkt.msg_kind = LoraMsgKind::BatchUp;
-  pkt.role = DeviceRole::Sender;
   pkt.device_id_short = short_id;
-  pkt.payload_type = PayloadType::TestCode;
+  pkt.payload_len = json.length();
-  pkt.payload_len = compressed_len;
+  memcpy(pkt.payload, json.c_str(), pkt.payload_len);
-  memcpy(pkt.payload, compressed, compressed_len);
+  if (!lora_send(pkt)) {
-  lora_send(pkt);
+    return;
+  }
+
+  uint8_t time_valid = 0;
+  uint32_t ack_epoch = 0;
+  int16_t ack_rssi = 0;
+  float ack_snr = 0.0f;
+  if (receive_ack_for_batch(g_test_batch_id, time_valid, ack_epoch, ack_rssi, ack_snr)) {
+    if (time_valid == 1 && ack_epoch >= MIN_ACCEPTED_EPOCH_UTC) {
+      time_set_utc(ack_epoch);
+    }
+    g_test_last_acked_batch_id = g_test_batch_id;
+    g_test_batch_id++;
+    if (SERIAL_DEBUG_MODE) {
+      Serial.printf("test ack: batch=%u time_valid=%u epoch=%lu rssi=%d snr=%.1f\n",
+                    static_cast<unsigned>(g_test_last_acked_batch_id),
+                    static_cast<unsigned>(time_valid),
+                    static_cast<unsigned long>(ack_epoch),
+                    static_cast<int>(ack_rssi),
+                    static_cast<double>(ack_snr));
+    }
+  }
 }
 
 void test_receiver_loop(SenderStatus *statuses, uint8_t count, uint16_t self_short_id) {
-  if (g_last_timesync_ms == 0) {
-    g_last_timesync_ms = millis() - (TIME_SYNC_INTERVAL_SEC * 1000UL - TEST_TIMESYNC_OFFSET_MS);
-  }
-  if (millis() - g_last_timesync_ms > TIME_SYNC_INTERVAL_SEC * 1000UL) {
-    g_last_timesync_ms = millis();
-    time_send_timesync(self_short_id);
-  }
-
   LoraPacket pkt = {};
   if (!lora_receive(pkt, 0)) {
     return;
   }
-  if (pkt.payload_type != PayloadType::TestCode) {
+  if (pkt.msg_kind != LoraMsgKind::BatchUp) {
     return;
   }
 
-  uint8_t decompressed[160];
+  uint8_t decompressed[192];
-  size_t decompressed_len = 0;
+  if (pkt.payload_len >= sizeof(decompressed)) {
-  if (!decompressBuffer(pkt.payload, pkt.payload_len, decompressed, sizeof(decompressed) - 1, decompressed_len)) {
     return;
   }
-  if (decompressed_len >= sizeof(decompressed)) {
+  memcpy(decompressed, pkt.payload, pkt.payload_len);
-    return;
+  decompressed[pkt.payload_len] = '\0';
-  }
-  decompressed[decompressed_len] = '\0';
 
-  StaticJsonDocument<128> doc;
+  StaticJsonDocument<192> doc;
   if (deserializeJson(doc, reinterpret_cast<const char *>(decompressed)) != DeserializationError::Ok) {
     return;
   }
 
   const char *id = doc["id"] | "";
   const char *code = doc["test_code"] | "";
+  uint16_t batch_id = static_cast<uint16_t>(doc["batch_id"] | 0);
+  uint32_t ts = doc["ts"] | 0;
   float bat_v = doc["bat_v"] | NAN;
 
+  uint8_t time_valid = 0;
+  uint32_t ack_epoch = 0;
+  send_test_ack(self_short_id, batch_id, time_valid, ack_epoch);
+
   for (uint8_t i = 0; i < count; ++i) {
     if (strncmp(statuses[i].last_data.device_id, id, sizeof(statuses[i].last_data.device_id)) == 0) {
       display_set_test_code_for_sender(i, code);
@@ -119,12 +210,34 @@ void test_receiver_loop(SenderStatus *statuses, uint8_t count, uint16_t self_sho
         statuses[i].last_data.battery_voltage_v = bat_v;
         statuses[i].last_data.battery_percent = battery_percent_from_voltage(bat_v);
       }
+      statuses[i].last_data.link_valid = true;
+      statuses[i].last_data.link_rssi_dbm = pkt.rssi_dbm;
+      statuses[i].last_data.link_snr_db = pkt.snr_db;
+      statuses[i].last_data.ts_utc = ts;
+      statuses[i].last_acked_batch_id = batch_id;
       statuses[i].has_data = true;
       statuses[i].last_update_ts_utc = time_get_utc();
       break;
     }
   }
 
-  mqtt_publish_test(id, String(reinterpret_cast<const char *>(decompressed)));
+  StaticJsonDocument<256> mqtt_doc;
+  mqtt_doc["id"] = id;
+  mqtt_doc["role"] = "receiver";
+  mqtt_doc["test_code"] = code;
+  mqtt_doc["ts"] = ts;
+  mqtt_doc["batch_id"] = batch_id;
+  mqtt_doc["acked_batch_id"] = batch_id;
+  if (!isnan(bat_v)) {
+    mqtt_doc["bat_v"] = bat_v;
+  }
+  mqtt_doc["rssi"] = pkt.rssi_dbm;
+  mqtt_doc["snr"] = pkt.snr_db;
+  mqtt_doc["time_valid"] = time_valid;
+  mqtt_doc["ack_epoch"] = ack_epoch;
+
+  String mqtt_payload;
+  serializeJson(mqtt_doc, mqtt_payload);
+  mqtt_publish_test(id, mqtt_payload);
 }
 #endif

src/time_manager.cpp

@@ -1,12 +1,8 @@
 #include "time_manager.h"
-#include "compressor.h"
-#include "config.h"
-#include "rtc_ds3231.h"
 #include <time.h>
 
 static bool g_time_synced = false;
 static bool g_tz_set = false;
-static bool g_rtc_present = false;
 static uint32_t g_last_sync_utc = 0;
 
 static void note_last_sync(uint32_t epoch) {
@@ -55,59 +51,6 @@ void time_set_utc(uint32_t epoch) {
   settimeofday(&tv, nullptr);
   g_time_synced = true;
   note_last_sync(epoch);
-
-  if (g_rtc_present) {
-    rtc_ds3231_set_epoch(epoch);
-  }
-}
-
-bool time_send_timesync(uint16_t device_id_short) {
-  uint32_t epoch = time_get_utc();
-  if (epoch == 0) {
-    return false;
-  }
-
-  char payload_str[32];
-  snprintf(payload_str, sizeof(payload_str), "T:%lu", static_cast<unsigned long>(epoch));
-
-  uint8_t compressed[LORA_MAX_PAYLOAD];
-  size_t compressed_len = 0;
-  if (!compressBuffer(reinterpret_cast<const uint8_t *>(payload_str), strlen(payload_str), compressed, sizeof(compressed), compressed_len)) {
-    return false;
-  }
-
-  LoraPacket pkt = {};
-  pkt.protocol_version = PROTOCOL_VERSION;
-  pkt.role = DeviceRole::Receiver;
-  pkt.device_id_short = device_id_short;
-  pkt.payload_type = PayloadType::TimeSync;
-  pkt.payload_len = compressed_len;
-  memcpy(pkt.payload, compressed, compressed_len);
-  return lora_send(pkt);
-}
-
-bool time_handle_timesync_payload(const uint8_t *payload, size_t len) {
-  uint8_t decompressed[64];
-  size_t decompressed_len = 0;
-  if (!decompressBuffer(payload, len, decompressed, sizeof(decompressed), decompressed_len)) {
-    return false;
-  }
-  if (decompressed_len >= sizeof(decompressed)) {
-    return false;
-  }
-  decompressed[decompressed_len] = '\0';
-
-  if (decompressed_len < 3 || decompressed[0] != 'T' || decompressed[1] != ':') {
-    return false;
-  }
-
-  uint32_t epoch = static_cast<uint32_t>(strtoul(reinterpret_cast<const char *>(decompressed + 2), nullptr, 10));
-  if (epoch == 0) {
-    return false;
-  }
-
-  time_set_utc(epoch);
-  return true;
 }
 
 void time_get_local_hhmm(char *out, size_t out_len) {
@@ -121,33 +64,6 @@ void time_get_local_hhmm(char *out, size_t out_len) {
   snprintf(out, out_len, "%02d:%02d", timeinfo.tm_hour, timeinfo.tm_min);
 }
 
-void time_rtc_init() {
-  if (!ENABLE_DS3231) {
-    g_rtc_present = false;
-    return;
-  }
-  g_rtc_present = rtc_ds3231_init();
-}
-
-bool time_try_load_from_rtc() {
-  if (!g_rtc_present) {
-    return false;
-  }
-  if (time_is_synced()) {
-    return true;
-  }
-  uint32_t epoch = 0;
-  if (!rtc_ds3231_read_epoch(epoch) || epoch == 0) {
-    return false;
-  }
-  time_set_utc(epoch);
-  return true;
-}
-
-bool time_rtc_present() {
-  return g_rtc_present;
-}
-
 uint32_t time_get_last_sync_utc() {
   return g_last_sync_utc;
 }

src/web_server.cpp

@@ -2,21 +2,110 @@
 #include <WebServer.h>
 #include "wifi_manager.h"
 #include "config.h"
+#include "sd_logger.h"
+#include "time_manager.h"
+#include "html_util.h"
+#include <SD.h>
+#include <WiFi.h>
+#include <time.h>
+#include <new>
+#include <limits.h>
+#include <math.h>
+#include <stdlib.h>
 
 static WebServer server(80);
 static const SenderStatus *g_statuses = nullptr;
 static uint8_t g_status_count = 0;
 static WifiMqttConfig g_config;
 static bool g_is_ap = false;
+static String g_web_user;
+static String g_web_pass;
 static const FaultCounters *g_sender_faults = nullptr;
 static const FaultType *g_sender_last_errors = nullptr;
 static MeterData g_last_batch[NUM_SENDERS][METER_BATCH_MAX_SAMPLES];
 static uint8_t g_last_batch_count[NUM_SENDERS] = {};
 
+struct HistoryBin {
+  uint32_t ts;
+  float value;
+  uint32_t count;
+};
+
+enum class HistoryMode : uint8_t {
+  Avg = 0,
+  Max = 1
+};
+
+struct HistoryJob {
+  bool active;
+  bool done;
+  bool error;
+  String error_msg;
+  String device_id;
+  HistoryMode mode;
+  uint32_t start_ts;
+  uint32_t end_ts;
+  uint32_t res_sec;
+  uint32_t bins_count;
+  uint32_t bins_filled;
+  uint16_t day_index;
+  File file;
+  HistoryBin *bins;
+};
+
+static HistoryJob g_history = {};
+static constexpr size_t SD_LIST_MAX_FILES = 200;
+static constexpr size_t SD_DOWNLOAD_MAX_PATH = 160;
+
+static int32_t round_power_w(float value) {
+  if (isnan(value)) {
+    return 0;
+  }
+  long rounded = lroundf(value);
+  if (rounded > INT32_MAX) {
+    return INT32_MAX;
+  }
+  if (rounded < INT32_MIN) {
+    return INT32_MIN;
+  }
+  return static_cast<int32_t>(rounded);
+}
+
+static bool auth_required() {
+  return g_is_ap ? WEB_AUTH_REQUIRE_AP : WEB_AUTH_REQUIRE_STA;
+}
+
+static const char *fault_text(FaultType fault) {
+  switch (fault) {
+    case FaultType::MeterRead:
+      return "meter";
+    case FaultType::Decode:
+      return "decode";
+    case FaultType::LoraTx:
+      return "loratx";
+    default:
+      return "none";
+  }
+}
+
+static bool ensure_auth() {
+  if (!auth_required()) {
+    return true;
+  }
+  const char *user = g_web_user.c_str();
+  const char *pass = g_web_pass.c_str();
+  if (server.authenticate(user, pass)) {
+    return true;
+  }
+  server.requestAuthentication(BASIC_AUTH, "DD3", "Authentication required");
+  return false;
+}
+
 static String html_header(const String &title) {
+  String safe_title = html_escape(title);
   String h = "<!DOCTYPE html><html><head><meta charset='utf-8'><meta name='viewport' content='width=device-width,initial-scale=1'>";
-  h += "<title>" + title + "</title></head><body>";
+  h += "<title>" + safe_title + "</title></head><body>";
-  h += "<h2>" + title + "</h2>";
+  h += "<h2>" + safe_title + "</h2>";
   return h;
 }
 
@@ -37,9 +126,223 @@ static String format_faults(uint8_t idx) {
   s += String(g_sender_faults[idx].lora_tx_fail);
   s += " last:";
   s += String(static_cast<uint8_t>(g_sender_last_errors[idx]));
+  s += " (" + String(fault_text(g_sender_last_errors[idx])) + ")";
   return s;
 }
 
+static bool sanitize_sd_download_path(String &path, String &error) {
+  path.trim();
+  if (path.length() == 0) {
+    error = "empty";
+    return false;
+  }
+  if (path.startsWith("dd3/")) {
+    path = "/" + path;
+  }
+  if (path.length() > SD_DOWNLOAD_MAX_PATH) {
+    error = "too_long";
+    return false;
+  }
+  if (!path.startsWith("/dd3/")) {
+    error = "prefix";
+    return false;
+  }
+  if (path.indexOf("..") >= 0) {
+    error = "dotdot";
+    return false;
+  }
+  if (path.indexOf('\\') >= 0) {
+    error = "backslash";
+    return false;
+  }
+  if (path.indexOf("//") >= 0) {
+    error = "repeated_slash";
+    return false;
+  }
+  return true;
+}
+
+static bool checkbox_checked(const char *name) {
+  if (!server.hasArg(name)) {
+    return false;
+  }
+  String val = server.arg(name);
+  return val == "on" || val == "true" || val == "1";
+}
+
+static bool sanitize_history_device_id(const String &input, String &out_device_id) {
+  if (sanitize_device_id(input, out_device_id)) {
+    return true;
+  }
+  if (g_statuses) {
+    for (uint8_t i = 0; i < g_status_count; ++i) {
+      String known = g_statuses[i].last_data.device_id;
+      if (input.equalsIgnoreCase(known) && sanitize_device_id(known, out_device_id)) {
+        return true;
+      }
+    }
+  }
+  return false;
+}
+
+static String sanitize_download_filename(const String &input, bool &clean) {
+  String out;
+  out.reserve(input.length());
+  clean = true;
+  for (size_t i = 0; i < input.length(); ++i) {
+    unsigned char c = static_cast<unsigned char>(input[i]);
+    if (c < 32 || c == 127 || c == '"' || c == '\\' || c == '/') {
+      out += '_';
+      clean = false;
+      continue;
+    }
+    out += static_cast<char>(c);
+  }
+  out.trim();
+  if (out.length() == 0) {
+    out = "download.bin";
+    clean = false;
+  }
+  return out;
+}
+
+static void history_reset() {
+  if (g_history.file) {
+    g_history.file.close();
+  }
+  if (g_history.bins) {
+    delete[] g_history.bins;
+  }
+  g_history = {};
+}
+
+static String history_date_from_epoch(uint32_t ts_utc) {
+  time_t t = static_cast<time_t>(ts_utc);
+  struct tm tm_utc;
+  gmtime_r(&t, &tm_utc);
+  char buf[16];
+  snprintf(buf, sizeof(buf), "%04d-%02d-%02d", tm_utc.tm_year + 1900, tm_utc.tm_mon + 1, tm_utc.tm_mday);
+  return String(buf);
+}
+
+static bool history_open_next_file() {
+  if (!g_history.active || g_history.done || g_history.error) {
+    return false;
+  }
+  if (g_history.file) {
+    g_history.file.close();
+  }
+  uint32_t day_ts = g_history.start_ts + static_cast<uint32_t>(g_history.day_index) * 86400UL;
+  if (day_ts > g_history.end_ts) {
+    g_history.done = true;
+    return false;
+  }
+  String path = String("/dd3/") + g_history.device_id + "/" + history_date_from_epoch(day_ts) + ".csv";
+  g_history.file = SD.open(path.c_str(), FILE_READ);
+  g_history.day_index++;
+  return true;
+}
+
+static bool history_parse_line(const char *line, uint32_t &ts_out, float &p_out) {
+  if (!line || line[0] < '0' || line[0] > '9') {
+    return false;
+  }
+  const char *comma = strchr(line, ',');
+  if (!comma) {
+    return false;
+  }
+  char ts_buf[16];
+  size_t ts_len = static_cast<size_t>(comma - line);
+  if (ts_len >= sizeof(ts_buf)) {
+    return false;
+  }
+  memcpy(ts_buf, line, ts_len);
+  ts_buf[ts_len] = '\0';
+  char *end = nullptr;
+  uint32_t ts = static_cast<uint32_t>(strtoul(ts_buf, &end, 10));
+  if (end == ts_buf) {
+    return false;
+  }
+  const char *p_start = comma + 1;
+  const char *p_end = strchr(p_start, ',');
+  char p_buf[16];
+  size_t p_len = p_end ? static_cast<size_t>(p_end - p_start) : strlen(p_start);
+  if (p_len >= sizeof(p_buf)) {
+    return false;
+  }
+  memcpy(p_buf, p_start, p_len);
+  p_buf[p_len] = '\0';
+  char *endp = nullptr;
+  float p = strtof(p_buf, &endp);
+  if (endp == p_buf) {
+    return false;
+  }
+  ts_out = ts;
+  p_out = p;
+  return true;
+}
+
+static void history_tick() {
+  if (!g_history.active || g_history.done || g_history.error) {
+    return;
+  }
+  if (!sd_logger_is_ready()) {
+    g_history.error = true;
+    g_history.error_msg = "sd_not_ready";
+    return;
+  }
+
+  uint32_t start_ms = millis();
+  while (millis() - start_ms < SD_HISTORY_TIME_BUDGET_MS) {
+    if (!g_history.file) {
+      if (!history_open_next_file()) {
+        if (g_history.done) {
+          g_history.active = false;
+        }
+        return;
+      }
+    }
+    if (!g_history.file.available()) {
+      g_history.file.close();
+      continue;
+    }
+
+    char line[160];
+    size_t n = g_history.file.readBytesUntil('\n', line, sizeof(line) - 1);
+    line[n] = '\0';
+    if (n == 0) {
+      continue;
+    }
+    uint32_t ts = 0;
+    float p = 0.0f;
+    if (!history_parse_line(line, ts, p)) {
+      continue;
+    }
+    if (ts < g_history.start_ts || ts > g_history.end_ts) {
+      continue;
+    }
+    uint32_t idx = (ts - g_history.start_ts) / g_history.res_sec;
+    if (idx >= g_history.bins_count) {
+      continue;
+    }
+    HistoryBin &bin = g_history.bins[idx];
+    if (bin.count == 0) {
+      bin.ts = g_history.start_ts + idx * g_history.res_sec;
+      bin.value = p;
+      bin.count = 1;
+      g_history.bins_filled++;
+    } else if (g_history.mode == HistoryMode::Avg) {
+      bin.value += p;
+      bin.count++;
+    } else {
+      if (p > bin.value) {
+        bin.value = p;
+      }
+      bin.count++;
+    }
+  }
+}
+
 static String render_sender_block(const SenderStatus &status) {
   String s;
   s += "<div style='margin-bottom:10px;padding:6px;border:1px solid #ccc'>";
@@ -52,24 +355,86 @@ static String render_sender_block(const SenderStatus &status) {
       }
     }
   }
-  s += "<strong>" + String(status.last_data.device_id) + "</strong>";
+  String device_id = status.last_data.device_id;
+  String device_id_safe = html_escape(device_id);
+  String device_id_url = url_encode_component(device_id);
+  s += "<strong><a href='/sender/" + device_id_url + "' target='_blank' rel='noopener noreferrer'>" + device_id_safe + "</a></strong>";
   if (status.has_data && status.last_data.link_valid) {
-    s += " R:" + String(status.last_data.link_rssi_dbm) + " S:" + String(status.last_data.link_snr_db, 1);
+    s += " RSSI:" + String(status.last_data.link_rssi_dbm) + " SNR:" + String(status.last_data.link_snr_db, 1);
+  }
+  if (status.has_data) {
+    s += " ack:" + String(status.last_acked_batch_id);
+    s += " err_tx:" + String(status.last_data.err_lora_tx);
+    s += " err_last:" + String(static_cast<uint8_t>(status.last_data.last_error));
+    s += " (" + String(fault_text(status.last_data.last_error)) + ")";
+    s += " rx_reject:" + String(status.last_data.rx_reject_reason);
+    s += " (" + String(rx_reject_reason_text(static_cast<RxRejectReason>(status.last_data.rx_reject_reason))) + ")";
   }
   s += format_faults(idx);
   s += "<br>";
   if (!status.has_data) {
     s += "No data";
   } else {
-    s += "Energy: " + String(status.last_data.energy_total_kwh, 3) + " kWh<br>";
+    if (status.last_data.energy_multi) {
-    s += "Power: " + String(status.last_data.total_power_w, 1) + " W<br>";
+      s += "Energy1: " + String(status.last_data.energy_kwh_int[0]) + " kWh<br>";
-    s += "Battery: " + String(status.last_data.battery_voltage_v, 2) + " V (" + String(status.last_data.battery_percent) + ")";
+      s += "Energy2: " + String(status.last_data.energy_kwh_int[1]) + " kWh<br>";
+      if (status.last_data.energy_meter_count >= 3) {
+        s += "Energy3: " + String(status.last_data.energy_kwh_int[2]) + " kWh<br>";
+      }
+    } else {
+      s += "Energy: " + String(status.last_data.energy_total_kwh, 2) + " kWh<br>";
+      s += "Power: " + String(round_power_w(status.last_data.total_power_w)) + " W<br>";
+      s += "P1/P2/P3: " + String(round_power_w(status.last_data.phase_power_w[0])) + " / " +
+           String(round_power_w(status.last_data.phase_power_w[1])) + " / " +
+           String(round_power_w(status.last_data.phase_power_w[2])) + " W<br>";
+    }
+    s += "Battery: " + String(status.last_data.battery_percent) + "% (" + String(status.last_data.battery_voltage_v, 2) + " V)";
   }
   s += "</div>";
   return s;
 }
 
+static void append_sd_listing(String &html, const String &dir_path, uint8_t depth, size_t &count) {
+  if (count >= SD_LIST_MAX_FILES || depth > 4) {
+    return;
+  }
+  File dir = SD.open(dir_path.c_str());
+  if (!dir || !dir.isDirectory()) {
+    return;
+  }
+  File entry = dir.openNextFile();
+  while (entry && count < SD_LIST_MAX_FILES) {
+    String name = entry.name();
+    String full_path = name;
+    if (!full_path.startsWith(dir_path)) {
+      if (!dir_path.endsWith("/")) {
+        full_path = dir_path + "/" + name;
+      } else {
+        full_path = dir_path + name;
+      }
+    }
+    if (entry.isDirectory()) {
+      html += "<li><strong>" + html_escape(full_path) + "/</strong></li>";
+      append_sd_listing(html, full_path, depth + 1, count);
+    } else {
+      String href = full_path;
+      if (!href.startsWith("/")) {
+        href = "/" + href;
+      }
+      String href_enc = url_encode_component(href);
+      html += "<li><a href='/sd/download?path=" + href_enc + "' target='_blank' rel='noopener noreferrer'>" + html_escape(full_path) + "</a>";
+      html += " (" + String(entry.size()) + " bytes)</li>";
+      count++;
+    }
+    entry = dir.openNextFile();
+  }
+  dir.close();
+}
+
 static void handle_root() {
+  if (!ensure_auth()) {
+    return;
+  }
   String html = html_header("DD3 Bridge Status");
   html += g_is_ap ? "<p>Mode: AP</p>" : "<p>Mode: STA</p>";
 
@@ -79,6 +444,18 @@ static void handle_root() {
     }
   }
 
+  if (sd_logger_is_ready()) {
+    html += "<h3>SD Files</h3><ul>";
+    size_t count = 0;
+    append_sd_listing(html, "/dd3", 0, count);
+    if (count >= SD_LIST_MAX_FILES) {
+      html += "<li>Listing truncated...</li>";
+    }
+    html += "</ul>";
+  } else {
+    html += "<p>SD: not ready</p>";
+  }
+
   html += "<p><a href='/wifi'>Configure WiFi/MQTT/NTP</a></p>";
   html += "<p><a href='/manual'>Manual</a></p>";
   html += html_footer();
@@ -86,16 +463,26 @@ static void handle_root() {
 }
 
 static void handle_wifi_get() {
+  if (!ensure_auth()) {
+    return;
+  }
   String html = html_header("WiFi/MQTT Config");
   html += "<form method='POST' action='/wifi'>";
-  html += "SSID: <input name='ssid' value='" + g_config.ssid + "'><br>";
+  html += "SSID: <input name='ssid' value='" + html_escape(g_config.ssid) + "'><br>";
-  html += "Password: <input name='pass' type='password' value='" + g_config.password + "'><br>";
+  html += "Password: <input name='pass' type='password'> ";
-  html += "MQTT Host: <input name='mqhost' value='" + g_config.mqtt_host + "'><br>";
+  html += "<label><input type='checkbox' name='clear_wifi_pass'> Clear password</label><br>";
+  html += "MQTT Host: <input name='mqhost' value='" + html_escape(g_config.mqtt_host) + "'><br>";
   html += "MQTT Port: <input name='mqport' value='" + String(g_config.mqtt_port) + "'><br>";
-  html += "MQTT User: <input name='mquser' value='" + g_config.mqtt_user + "'><br>";
+  html += "MQTT User: <input name='mquser' value='" + html_escape(g_config.mqtt_user) + "'><br>";
-  html += "MQTT Pass: <input name='mqpass' type='password' value='" + g_config.mqtt_pass + "'><br>";
+  html += "MQTT Pass: <input name='mqpass' type='password'> ";
-  html += "NTP Server 1: <input name='ntp1' value='" + g_config.ntp_server_1 + "'><br>";
+  html += "<label><input type='checkbox' name='clear_mqtt_pass'> Clear password</label><br>";
-  html += "NTP Server 2: <input name='ntp2' value='" + g_config.ntp_server_2 + "'><br>";
+  html += "NTP Server 1: <input name='ntp1' value='" + html_escape(g_config.ntp_server_1) + "'><br>";
+  html += "NTP Server 2: <input name='ntp2' value='" + html_escape(g_config.ntp_server_2) + "'><br>";
+  html += "<hr>";
+  html += "Web UI User: <input name='webuser' value='" + html_escape(g_config.web_user) + "'><br>";
+  html += "Web UI Pass: <input name='webpass' type='password'> ";
+  html += "<label><input type='checkbox' name='clear_web_pass'> Clear password</label><br>";
+  html += "<div style='font-size:12px;color:#666;'>Leaving password blank keeps the existing one.</div>";
   html += "<button type='submit'>Save</button>";
   html += "</form>";
   html += html_footer();
@@ -103,15 +490,38 @@ static void handle_wifi_get() {
 }
 
 static void handle_wifi_post() {
-  WifiMqttConfig cfg;
+  if (!ensure_auth()) {
-  cfg.ntp_server_1 = "pool.ntp.org";
+    return;
-  cfg.ntp_server_2 = "time.nist.gov";
+  }
+  WifiMqttConfig cfg = g_config;
+  cfg.ntp_server_1 = g_config.ntp_server_1.length() > 0 ? g_config.ntp_server_1 : "pool.ntp.org";
+  cfg.ntp_server_2 = g_config.ntp_server_2.length() > 0 ? g_config.ntp_server_2 : "time.nist.gov";
   cfg.ssid = server.arg("ssid");
-  cfg.password = server.arg("pass");
+  String wifi_pass = server.arg("pass");
+  if (checkbox_checked("clear_wifi_pass")) {
+    cfg.password = "";
+  } else if (wifi_pass.length() > 0) {
+    cfg.password = wifi_pass;
+  }
   cfg.mqtt_host = server.arg("mqhost");
   cfg.mqtt_port = static_cast<uint16_t>(server.arg("mqport").toInt());
   cfg.mqtt_user = server.arg("mquser");
-  cfg.mqtt_pass = server.arg("mqpass");
+  String mqtt_pass = server.arg("mqpass");
+  if (checkbox_checked("clear_mqtt_pass")) {
+    cfg.mqtt_pass = "";
+  } else if (mqtt_pass.length() > 0) {
+    cfg.mqtt_pass = mqtt_pass;
+  }
+  String web_user = server.arg("webuser");
+  if (web_user.length() > 0) {
+    cfg.web_user = web_user;
+  }
+  String web_pass = server.arg("webpass");
+  if (checkbox_checked("clear_web_pass")) {
+    cfg.web_pass = "";
+  } else if (web_pass.length() > 0) {
+    cfg.web_pass = web_pass;
+  }
   if (server.arg("ntp1").length() > 0) {
     cfg.ntp_server_1 = server.arg("ntp1");
   }
@@ -119,6 +529,9 @@ static void handle_wifi_post() {
     cfg.ntp_server_2 = server.arg("ntp2");
   }
   cfg.valid = true;
+  g_config = cfg;
+  g_web_user = cfg.web_user;
+  g_web_pass = cfg.web_pass;
   wifi_save_config(cfg);
   server.send(200, "text/html", "<html><body>Saved. Rebooting...</body></html>");
   delay(1000);
@@ -126,37 +539,103 @@ static void handle_wifi_post() {
 }
 
 static void handle_sender() {
+  if (!ensure_auth()) {
+    return;
+  }
   if (!g_statuses) {
     server.send(404, "text/plain", "No senders");
     return;
   }
   String uri = server.uri();
   String device_id = uri.substring(String("/sender/").length());
+  String device_id_url = url_encode_component(device_id);
   for (uint8_t i = 0; i < g_status_count; ++i) {
     if (device_id.equalsIgnoreCase(g_statuses[i].last_data.device_id)) {
       String html = html_header("Sender " + device_id);
       html += render_sender_block(g_statuses[i]);
+      html += "<h3>History (Power)</h3>";
+      html += "<div>";
+      html += "Days: <input id='hist_days' type='number' min='1' max='" + String(SD_HISTORY_MAX_DAYS) + "' value='7' style='width:60px'> ";
+      html += "Res(min): <input id='hist_res' type='number' min='" + String(SD_HISTORY_MIN_RES_MIN) + "' value='5' style='width:60px'> ";
+      html += "<select id='hist_mode'><option value='avg'>avg</option><option value='max'>max</option></select> ";
+      html += "<button onclick='drawHistory()'>Draw</button>";
+      html += "<div id='hist_status' style='font-size:12px;margin-top:4px;color:#666;'></div>";
+      html += "<canvas id='hist_canvas' width='320' height='140' style='width:100%;max-width:520px;border:1px solid #ccc;margin-top:6px;'></canvas>";
+      html += "</div>";
+      html += "<script>";
+      html += "const deviceId='" + device_id_url + "';";
+      html += "let histTimer=null;";
+      html += "function histStatus(msg){document.getElementById('hist_status').textContent=msg;}";
+      html += "function drawHistory(){";
+      html += "const days=document.getElementById('hist_days').value;";
+      html += "const res=document.getElementById('hist_res').value;";
+      html += "const mode=document.getElementById('hist_mode').value;";
+      html += "histStatus('Starting...');";
+      html += "fetch(`/history/start?device_id=${deviceId}&days=${days}&res=${res}&mode=${mode}`)";
+      html += ".then(r=>r.json()).then(j=>{";
+      html += "if(!j.ok){histStatus('Error: '+(j.error||'failed'));return;}";
+      html += "if(histTimer){clearInterval(histTimer);}";
+      html += "histTimer=setInterval(()=>fetchHistory(),1000);";
+      html += "fetchHistory();";
+      html += "});";
+      html += "}";
+      html += "function fetchHistory(){";
+      html += "fetch(`/history/data?device_id=${deviceId}`).then(r=>r.json()).then(j=>{";
+      html += "if(!j.ready){histStatus(j.error?('Error: '+j.error):('Processing... '+(j.progress||0)+'%'));return;}";
+      html += "if(histTimer){clearInterval(histTimer);histTimer=null;}";
+      html += "renderChart(j.series);";
+      html += "histStatus('Done');";
+      html += "});";
+      html += "}";
+      html += "function renderChart(series){";
+      html += "const canvas=document.getElementById('hist_canvas');";
+      html += "const w=canvas.clientWidth;const h=canvas.clientHeight;";
+      html += "canvas.width=w;canvas.height=h;";
+      html += "const ctx=canvas.getContext('2d');";
+      html += "ctx.clearRect(0,0,w,h);";
+      html += "if(!series||series.length===0){ctx.fillText('No data',10,20);return;}";
+      html += "let min=Infinity,max=-Infinity;";
+      html += "for(const p of series){if(p[1]===null)continue; if(p[1]<min)min=p[1]; if(p[1]>max)max=p[1];}";
+      html += "if(!isFinite(min)||!isFinite(max)){ctx.fillText('No data',10,20);return;}";
+      html += "if(min===max){min=0;}";
+      html += "ctx.strokeStyle='#333';ctx.lineWidth=1;ctx.beginPath();";
+      html += "let first=true;";
+      html += "for(let i=0;i<series.length;i++){";
+      html += "const v=series[i][1];";
+      html += "if(v===null)continue;";
+      html += "const x=(i/(series.length-1))* (w-2) + 1;";
+      html += "const y=h-2-((v-min)/(max-min))*(h-4);";
+      html += "if(first){ctx.moveTo(x,y);first=false;} else {ctx.lineTo(x,y);} }";
+      html += "ctx.stroke();";
+      html += "ctx.fillStyle='#666';ctx.fillText(min.toFixed(0)+'W',4,h-4);";
+      html += "ctx.fillText(max.toFixed(0)+'W',4,12);";
+      html += "}";
+      html += "</script>";
       if (g_last_batch_count[i] > 0) {
         html += "<h3>Last batch (" + String(g_last_batch_count[i]) + " samples)</h3>";
         html += "<table border='1' cellspacing='0' cellpadding='3'>";
-        html += "<tr><th>#</th><th>ts</th><th>e_kwh</th><th>p_w</th><th>p1_w</th><th>p2_w</th><th>p3_w</th>";
+        html += "<tr><th>#</th><th>ts</th><th>energy1_kwh</th><th>energy2_kwh</th><th>energy3_kwh</th><th>p_w</th><th>p1_w</th><th>p2_w</th><th>p3_w</th>";
-        html += "<th>bat_v</th><th>bat_pct</th><th>rssi</th><th>snr</th><th>err_tx</th><th>err_last</th></tr>";
+        html += "<th>bat_v</th><th>bat_pct</th><th>rssi</th><th>snr</th><th>err_tx</th><th>err_last</th><th>rx_reject</th></tr>";
         for (uint8_t r = 0; r < g_last_batch_count[i]; ++r) {
           const MeterData &d = g_last_batch[i][r];
           html += "<tr>";
           html += "<td>" + String(r) + "</td>";
           html += "<td>" + String(d.ts_utc) + "</td>";
-          html += "<td>" + String(d.energy_total_kwh, 3) + "</td>";
+          html += "<td>" + String(d.energy_kwh_int[0]) + "</td>";
-          html += "<td>" + String(d.total_power_w, 1) + "</td>";
+          html += "<td>" + String(d.energy_kwh_int[1]) + "</td>";
-          html += "<td>" + String(d.phase_power_w[0], 1) + "</td>";
+          html += "<td>" + String(d.energy_kwh_int[2]) + "</td>";
-          html += "<td>" + String(d.phase_power_w[1], 1) + "</td>";
+          html += "<td>" + String(round_power_w(d.total_power_w)) + "</td>";
-          html += "<td>" + String(d.phase_power_w[2], 1) + "</td>";
+          html += "<td>" + String(round_power_w(d.phase_power_w[0])) + "</td>";
+          html += "<td>" + String(round_power_w(d.phase_power_w[1])) + "</td>";
+          html += "<td>" + String(round_power_w(d.phase_power_w[2])) + "</td>";
           html += "<td>" + String(d.battery_voltage_v, 2) + "</td>";
           html += "<td>" + String(d.battery_percent) + "</td>";
           html += "<td>" + String(d.link_rssi_dbm) + "</td>";
           html += "<td>" + String(d.link_snr_db, 1) + "</td>";
           html += "<td>" + String(d.err_lora_tx) + "</td>";
-          html += "<td>" + String(static_cast<uint8_t>(d.last_error)) + "</td>";
+          html += "<td>" + String(static_cast<uint8_t>(d.last_error)) + " (" + String(fault_text(d.last_error)) + ")</td>";
+          html += "<td>" + String(d.rx_reject_reason) + " (" +
+                  String(rx_reject_reason_text(static_cast<RxRejectReason>(d.rx_reject_reason))) + ")</td>";
           html += "</tr>";
         }
         html += "</table>";
@@ -170,22 +649,198 @@ static void handle_sender() {
 }
 
 static void handle_manual() {
+  if (!ensure_auth()) {
+    return;
+  }
   String html = html_header("DD3 Manual");
   html += "<ul>";
   html += "<li>Energy: total kWh since meter start.</li>";
   html += "<li>Power: total active power in W.</li>";
   html += "<li>P1/P2/P3: phase power in W.</li>";
-  html += "<li>bat_v: battery voltage (V), bat_pct: estimated percent.</li>";
+  html += "<li>Battery: percent with voltage in V.</li>";
   html += "<li>RSSI/SNR: LoRa link quality from last packet.</li>";
-  html += "<li>err_tx: LoRa TX error count; err_last: last error code.</li>";
+  html += "<li>err_tx: sender-side LoRa TX error counter.</li>";
-  html += "<li>faults m/d/tx: meter read/decode/tx counters.</li>";
+  html += "<li>err_last: last error code (0=None, 1=MeterRead, 2=Decode, 3=LoraTx).</li>";
+  html += "<li>rx_reject: last RX reject reason (0=None, 1=crc_fail, 2=invalid_msg_kind, 3=length_mismatch, 4=device_id_mismatch, 5=batch_id_mismatch).</li>";
+  html += "<li>faults m/d/tx: receiver-side counters (meter read fails, decode fails, LoRa TX fails).</li>";
+  html += "<li>faults last: last receiver-side error code (same mapping as err_last).</li>";
   html += "</ul>";
   html += html_footer();
   server.send(200, "text/html", html);
 }
 
+static void handle_history_start() {
+  if (!ensure_auth()) {
+    return;
+  }
+  if (!sd_logger_is_ready()) {
+    server.send(200, "application/json", "{\"ok\":false,\"error\":\"sd_not_ready\"}");
+    return;
+  }
+  if (!time_is_synced()) {
+    server.send(200, "application/json", "{\"ok\":false,\"error\":\"time_not_synced\"}");
+    return;
+  }
+  String device_id_arg = server.arg("device_id");
+  String device_id;
+  if (!sanitize_history_device_id(device_id_arg, device_id)) {
+    server.send(200, "application/json", "{\"ok\":false,\"error\":\"bad_device_id\"}");
+    return;
+  }
+  uint16_t days = static_cast<uint16_t>(server.arg("days").toInt());
+  uint16_t res_min = static_cast<uint16_t>(server.arg("res").toInt());
+  String mode_str = server.arg("mode");
+  if (device_id.length() == 0 || days == 0 || res_min == 0) {
+    server.send(200, "application/json", "{\"ok\":false,\"error\":\"bad_params\"}");
+    return;
+  }
+  if (days > SD_HISTORY_MAX_DAYS) {
+    days = SD_HISTORY_MAX_DAYS;
+  }
+  if (res_min < SD_HISTORY_MIN_RES_MIN) {
+    res_min = SD_HISTORY_MIN_RES_MIN;
+  }
+  uint32_t bins = (static_cast<uint32_t>(days) * 24UL * 60UL) / res_min;
+  if (bins == 0 || bins > SD_HISTORY_MAX_BINS) {
+    String resp = String("{\"ok\":false,\"error\":\"too_many_bins\",\"max_bins\":") + SD_HISTORY_MAX_BINS + "}";
+    server.send(200, "application/json", resp);
+    return;
+  }
+
+  history_reset();
+  g_history.active = true;
+  g_history.done = false;
+  g_history.error = false;
+  g_history.device_id = device_id;
+  g_history.mode = (mode_str == "max") ? HistoryMode::Max : HistoryMode::Avg;
+  g_history.res_sec = static_cast<uint32_t>(res_min) * 60UL;
+  g_history.bins_count = bins;
+  g_history.day_index = 0;
+  g_history.bins = new (std::nothrow) HistoryBin[bins];
+  if (!g_history.bins) {
+    g_history.error = true;
+    g_history.error_msg = "oom";
+    server.send(200, "application/json", "{\"ok\":false,\"error\":\"oom\"}");
+    return;
+  }
+  for (uint32_t i = 0; i < bins; ++i) {
+    g_history.bins[i] = {};
+  }
+  g_history.end_ts = time_get_utc();
+  uint32_t span = static_cast<uint32_t>(days) * 86400UL;
+  g_history.start_ts = g_history.end_ts > span ? (g_history.end_ts - span) : 0;
+  if (g_history.res_sec > 0) {
+    g_history.start_ts = (g_history.start_ts / g_history.res_sec) * g_history.res_sec;
+  }
+
+  String resp = String("{\"ok\":true,\"bins\":") + bins + "}";
+  server.send(200, "application/json", resp);
+}
+
+static void handle_history_data() {
+  if (!ensure_auth()) {
+    return;
+  }
+  String device_id_arg = server.arg("device_id");
+  String device_id;
+  if (!sanitize_history_device_id(device_id_arg, device_id)) {
+    server.send(200, "application/json", "{\"ready\":false,\"error\":\"bad_device_id\"}");
+    return;
+  }
+  if (!g_history.bins || device_id.length() == 0 || device_id != g_history.device_id) {
+    server.send(200, "application/json", "{\"ready\":false,\"error\":\"no_job\"}");
+    return;
+  }
+  if (g_history.error) {
+    String resp = String("{\"ready\":false,\"error\":\"") + g_history.error_msg + "\"}";
+    server.send(200, "application/json", resp);
+    return;
+  }
+  if (g_history.active && !g_history.done) {
+    uint32_t progress = g_history.bins_count == 0 ? 0 : (g_history.bins_filled * 100UL / g_history.bins_count);
+    String resp = String("{\"ready\":false,\"progress\":") + progress + "}";
+    server.send(200, "application/json", resp);
+    return;
+  }
+
+  server.setContentLength(CONTENT_LENGTH_UNKNOWN);
+  server.send(200, "application/json", "");
+  server.sendContent("{\"ready\":true,\"series\":[");
+  bool first = true;
+  for (uint32_t i = 0; i < g_history.bins_count; ++i) {
+    const HistoryBin &bin = g_history.bins[i];
+    if (!first) {
+      server.sendContent(",");
+    }
+    first = false;
+    float value = NAN;
+    if (bin.count > 0) {
+      value = (g_history.mode == HistoryMode::Avg) ? (bin.value / static_cast<float>(bin.count)) : bin.value;
+    }
+    if (bin.count == 0) {
+      server.sendContent(String("[") + bin.ts + ",null]");
+    } else {
+      int32_t rounded = round_power_w(value);
+      server.sendContent(String("[") + bin.ts + "," + String(rounded) + "]");
+    }
+  }
+  server.sendContent("]}");
+}
+
+static void handle_sd_download() {
+  if (!ensure_auth()) {
+    return;
+  }
+  if (!sd_logger_is_ready()) {
+    server.send(404, "text/plain", "SD not ready");
+    return;
+  }
+  String path = server.arg("path");
+  String error;
+  if (!sanitize_sd_download_path(path, error)) {
+    if (SERIAL_DEBUG_MODE) {
+      Serial.printf("sd: reject path '%s' reason=%s\n", path.c_str(), error.c_str());
+    }
+    server.send(400, "text/plain", "Invalid path");
+    return;
+  }
+  File f = SD.open(path.c_str(), FILE_READ);
+  if (!f) {
+    server.send(404, "text/plain", "Not found");
+    return;
+  }
+  size_t size = f.size();
+  String filename = path.substring(path.lastIndexOf('/') + 1);
+  bool name_clean = true;
+  (void)name_clean;
+  String safe_name = sanitize_download_filename(filename, name_clean);
+  String cd = "attachment; filename=\"" + safe_name + "\"; filename*=UTF-8''" + url_encode_component(safe_name);
+  server.sendHeader("Content-Disposition", cd);
+  server.setContentLength(size);
+  const char *content_type = "application/octet-stream";
+  if (filename.endsWith(".csv")) {
+    content_type = "text/csv";
+  } else if (filename.endsWith(".txt")) {
+    content_type = "text/plain";
+  }
+  server.send(200, content_type, "");
+  WiFiClient client = server.client();
+  uint8_t buf[512];
+  while (f.available()) {
+    size_t n = f.read(buf, sizeof(buf));
+    if (n == 0) {
+      break;
+    }
+    client.write(buf, n);
+    delay(0);
+  }
+  f.close();
+}
+
 void web_server_set_config(const WifiMqttConfig &config) {
   g_config = config;
+  g_web_user = config.web_user;
+  g_web_pass = config.web_pass;
 }
 
 void web_server_set_sender_faults(const FaultCounters *faults, const FaultType *last_errors) {
@@ -213,6 +868,9 @@ void web_server_begin_ap(const SenderStatus *statuses, uint8_t count) {
 
   server.on("/", handle_root);
   server.on("/manual", handle_manual);
+  server.on("/history/start", handle_history_start);
+  server.on("/history/data", handle_history_data);
+  server.on("/sd/download", handle_sd_download);
   server.on("/wifi", HTTP_GET, handle_wifi_get);
   server.on("/wifi", HTTP_POST, handle_wifi_post);
   server.on("/sender/", handle_sender);
@@ -234,6 +892,9 @@ void web_server_begin_sta(const SenderStatus *statuses, uint8_t count) {
   server.on("/", handle_root);
   server.on("/manual", handle_manual);
   server.on("/sender/", handle_sender);
+  server.on("/history/start", handle_history_start);
+  server.on("/history/data", handle_history_data);
+  server.on("/sd/download", handle_sd_download);
   server.on("/wifi", HTTP_GET, handle_wifi_get);
   server.on("/wifi", HTTP_POST, handle_wifi_post);
   server.onNotFound([]() {
@@ -247,5 +908,6 @@ void web_server_begin_sta(const SenderStatus *statuses, uint8_t count) {
 }
 
 void web_server_loop() {
+  history_tick();
   server.handleClient();
 }

src/wifi_manager.cpp

@@ -1,4 +1,5 @@
 #include "wifi_manager.h"
+#include "config.h"
 #include <WiFi.h>
 #include <esp_wifi.h>
 
@@ -10,9 +11,6 @@ void wifi_manager_init() {
 
 bool wifi_load_config(WifiMqttConfig &config) {
   config.valid = prefs.getBool("valid", false);
-  if (!config.valid) {
-    return false;
-  }
   config.ssid = prefs.getString("ssid", "");
   config.password = prefs.getString("pass", "");
   config.mqtt_host = prefs.getString("mqhost", "");
@@ -21,6 +19,11 @@ bool wifi_load_config(WifiMqttConfig &config) {
   config.mqtt_pass = prefs.getString("mqpass", "");
   config.ntp_server_1 = prefs.getString("ntp1", "pool.ntp.org");
   config.ntp_server_2 = prefs.getString("ntp2", "time.nist.gov");
+  config.web_user = prefs.getString("webuser", WEB_AUTH_DEFAULT_USER);
+  config.web_pass = prefs.getString("webpass", WEB_AUTH_DEFAULT_PASS);
+  if (!config.valid) {
+    return false;
+  }
   return config.ssid.length() > 0 && config.mqtt_host.length() > 0;
 }
 
@@ -34,6 +37,8 @@ bool wifi_save_config(const WifiMqttConfig &config) {
   prefs.putString("mqpass", config.mqtt_pass);
   prefs.putString("ntp1", config.ntp_server_1);
   prefs.putString("ntp2", config.ntp_server_2);
+  prefs.putString("webuser", config.web_user);
+  prefs.putString("webpass", config.web_pass);
   return true;
 }
 

test/test_html_escape/test_html_escape.cpp

@@ -0,0 +1,37 @@
+#include <Arduino.h>
+#include <unity.h>
+#include "html_util.h"
+
+static void test_html_escape_basic() {
+  TEST_ASSERT_EQUAL_STRING("", html_escape("").c_str());
+  TEST_ASSERT_EQUAL_STRING("plain", html_escape("plain").c_str());
+  TEST_ASSERT_EQUAL_STRING("a&amp;b", html_escape("a&b").c_str());
+  TEST_ASSERT_EQUAL_STRING("&lt;tag&gt;", html_escape("<tag>").c_str());
+  TEST_ASSERT_EQUAL_STRING("&quot;hi&quot;", html_escape("\"hi\"").c_str());
+  TEST_ASSERT_EQUAL_STRING("it&#39;s", html_escape("it's").c_str());
+  TEST_ASSERT_EQUAL_STRING("&amp;&lt;&gt;&quot;&#39;", html_escape("&<>\"'").c_str());
+}
+
+static void test_sanitize_device_id() {
+  String out;
+  TEST_ASSERT_TRUE(sanitize_device_id("F19C", out));
+  TEST_ASSERT_EQUAL_STRING("dd3-F19C", out.c_str());
+  TEST_ASSERT_TRUE(sanitize_device_id("dd3-f19c", out));
+  TEST_ASSERT_EQUAL_STRING("dd3-F19C", out.c_str());
+  TEST_ASSERT_FALSE(sanitize_device_id("F19G", out));
+  TEST_ASSERT_FALSE(sanitize_device_id("dd3-12", out));
+  TEST_ASSERT_FALSE(sanitize_device_id("dd3-12345", out));
+  TEST_ASSERT_FALSE(sanitize_device_id("../F19C", out));
+  TEST_ASSERT_FALSE(sanitize_device_id("dd3-%2f", out));
+  TEST_ASSERT_FALSE(sanitize_device_id("dd3-12/3", out));
+  TEST_ASSERT_FALSE(sanitize_device_id("dd3-12\\3", out));
+}
+
+void setup() {
+  UNITY_BEGIN();
+  RUN_TEST(test_html_escape_basic);
+  RUN_TEST(test_sanitize_device_id);
+  UNITY_END();
+}
+
+void loop() {}