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

docs: rewrite README for current multi-meter behavior
Document multi-meter UART mapping and energy-only sender behavior
2026-02-04 20:12:02 +01:00 · 2026-02-04 19:03:43 +01:00 · 2026-02-04 15:22:30 +01:00 · 2026-02-04 15:22:24 +01:00
12 changed files with 552 additions and 356 deletions
--- a/README.md
+++ b/README.md
@@ -1,88 +1,129 @@
 # DD3-LoRa-Bridge-MultiSender

-Unified firmware for LilyGO T3 v1.6.1 (ESP32 + SX1276 + SSD1306) running as either:
- `Sender`: reads meter values and sends binary batches over LoRa.
- `Receiver`: accepts batches, ACKs with optional time, publishes to MQTT/web.
+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.

-## Protocol (minimal)
+## Current Architecture

-Frame format:
+- Single codebase, role selected at boot via `detect_role()` (`include/config.h`, `src/config.cpp`).
+- LoRa link uses explicit CRC16 frame protection in firmware (`src/lora_transport.cpp`), in addition to LoRa PHY CRC.
+- Sender batches up to `30` samples and retransmits on missing ACK (`BATCH_MAX_RETRIES=2`, policy `Keep`).
+- Receiver handles AP fallback when STA config is missing/invalid and exposes a config/status web UI.

-`[msg_kind:1][dev_id_short:2][payload...][crc16:2]`
+## LoRa Frame Protocol (Current)
+
+Frame format on-air:
+
+`[msg_kind:1][device_short_id:2][payload...][crc16:2]`

 `msg_kind`:
- `0`: `BATCH_UP` (Sender -> Receiver)
- `1`: `ACK_DOWN` (Receiver -> Sender)
+- `0` = `BatchUp`
+- `1` = `AckDown`

-Removed from protocol:
- protocol version field
- payload type field
- MeterData JSON/compressed LoRa path
- standalone TimeSync packets
+### `BatchUp`

-CRC16 validation is still required on every frame.
+`BatchUp` is chunked in transport (`batch_id`, `chunk_index`, `chunk_count`, `total_len`) and then decoded via `payload_codec`.

-## Payloads
+Payload header contains:
+- fixed magic/schema fields (`kMagic=0xDDB3`, `kSchema=2`)
+- `schema_id`
+- sender/batch/time/error metadata

-### 1) `BATCH_UP`
- Uses existing binary batch/chunk transport.
- `sample_count == 0` is valid and means `SYNC_REQUEST`.
+Supported payload schemas in this branch:
+- `schema_id=1` (`EnergyMulti`): integer kWh for up to 3 meters (`energy1_kwh`, `energy2_kwh`, `energy3_kwh`)
+- `schema_id=0` (legacy): older energy/power delta encoding path remains decode-compatible

-### 2) `ACK_DOWN` (7 bytes)
- `flags` (`u8`): bit0 = `time_valid`
- `batch_id` (`u16`, big-endian)
- `epoch_utc` (`u32`, big-endian)
+`n == 0` is used as sync request (no meter samples).

-Receiver sets:
- `time_valid=1` only when receiver time is authoritative and sane.
- Otherwise `time_valid=0` and `epoch_utc=0`.
+### `AckDown` (7 bytes)

-## Time bootstrap safety
+`[flags:1][batch_id_be:2][epoch_utc_be:4]`

-Sender starts with:
+- `flags bit0`: `time_valid`
+- Receiver sends ACK repeatedly (`ACK_REPEAT_COUNT=3`, `ACK_REPEAT_DELAY_MS=200`).
+- Sender accepts time only if `time_valid=1` and `epoch >= MIN_ACCEPTED_EPOCH_UTC` (`2026-02-01 00:00:00 UTC`).
+
+## Time Bootstrap Guardrail
+
+On sender boot:
 - `g_time_acquired=false`
- no real sampling/batching
- periodic `SYNC_REQUEST` every `SYNC_REQUEST_INTERVAL_MS` (default `15000ms`)
+- only sync requests every `SYNC_REQUEST_INTERVAL_MS` (15s)
+- no normal sampling/transmit until valid ACK time received

-Sender only accepts time from `ACK_DOWN` if:
- `time_valid == 1`
- `epoch_utc >= 2026-02-01 00:00:00 UTC` (`MIN_ACCEPTED_EPOCH_UTC = 1769904000`)
+This prevents publishing/storing pre-threshold timestamps.

-Only then:
- system time is set
- `g_time_acquired=true`
- normal 1 Hz sampling + batch transmit starts
+## Multi-Meter Sender Behavior

-This guarantees no pre-`2026-02-01` epoch reaches MQTT or SD/DB paths.
+Implemented in `src/meter_driver.cpp` + sender path in `src/main.cpp`:

-## Receiver behavior
+- Meter protocol: IEC 62056-21 ASCII, Mode D style framing (`/ ... !`)
+- UART settings: `9600 7E1`
+- Parsed OBIS: `1-0:1.8.0`
+- Conversion: floor to integer kWh (`floorf`)

-On `BATCH_UP`:
-1. Decode batch/chunks.
-2. Send `ACK_DOWN` immediately.
-3. If `sample_count == 0`: treat as `SYNC_REQUEST`, do not publish MQTT/update stats.
-4. Else decode and publish samples as normal.
+Meter count is build-dependent (`include/config.h`):
+- Debug builds (`SERIAL_DEBUG_MODE=1`): `METER_COUNT=2`
+- Prod builds (`SERIAL_DEBUG_MODE=0`): `METER_COUNT=3`

-## Sender/Receiver debug logs (`SERIAL_DEBUG_MODE`)
+Default RX pins:
+- Meter1: `GPIO34` (`Serial2`)
+- Meter2: `GPIO25` (`Serial1`)
+- Meter3: `GPIO3` (`Serial`, prod only because debug serial is disabled)

-Sender:
- `sync: request tx batch_id=%u`
- `ack: rx ok batch_id=%u time_valid=%u epoch=%lu set=%u`
- `ack: timeout batch_id=%u retry=%u`
+## Receiver Behavior

-Receiver:
- `ack: tx batch_id=%u time_valid=%u epoch=%lu samples=%u`
+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.

-## Removed hardware dependency
+## MQTT Topics and Payloads

-DS3231 RTC support was removed:
- no RTC files
- no RTC init/load/set logic
- no `ENABLE_DS3231` flow
+State topic:
+- `smartmeter/<device_id>/state`

-## Build
+Fault topic (retained):
+- `smartmeter/<device_id>/faults`
+
+For `EnergyMulti` samples, state JSON includes:
+- `id`, `ts`
+- `energy1_kwh`, `energy2_kwh`, optional `energy3_kwh`
+- `bat_v`, `bat_pct`
+- optional link fields: `rssi`, `snr`
+- fault/reject fields: `err_last`, `rx_reject`, `rx_reject_text` (+ non-zero counters)
+
+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`.
+
+## Web UI, Wi-Fi, Storage
+
+- STA config is stored in Preferences (`wifi_manager`).
+- If STA/MQTT config is unavailable, receiver starts AP mode with SSID prefix `DD3-Bridge-`.
+- Web auth defaults are `admin/admin` (`WEB_AUTH_DEFAULT_USER/PASS`).
+- SD logging is enabled (`ENABLE_SD_LOGGING=true`).
+
+## Build Environments
+
+From `platformio.ini`:
+
+- `lilygo-t3-v1-6-1`
+- `lilygo-t3-v1-6-1-test`
+- `lilygo-t3-v1-6-1-868`
+- `lilygo-t3-v1-6-1-868-test`
+- `lilygo-t3-v1-6-1-payload-test`
+- `lilygo-t3-v1-6-1-868-payload-test`
+- `lilygo-t3-v1-6-1-prod`
+- `lilygo-t3-v1-6-1-868-prod`
+
+Example:

 ```bash
-pio run -e lilygo-t3-v1-6-1
-pio run -e lilygo-t3-v1-6-1-test
+~/.platformio/penv/bin/pio run -e lilygo-t3-v1-6-1
 ```
+
+## Test Mode
+
+`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`.
--- a/include/config.h
+++ b/include/config.h
@@ -32,7 +32,9 @@ constexpr uint8_t PIN_BAT_ADC = 35;
 constexpr uint8_t PIN_ROLE = 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
@@ -68,6 +70,9 @@ constexpr bool ENABLE_HA_DISCOVERY = true;
 #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;
--- a/include/data_model.h
+++ b/include/data_model.h
@@ -28,6 +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;
@@ -47,6 +50,7 @@ struct MeterData {
 struct SenderStatus {
  MeterData last_data;
  uint32_t last_update_ts_utc;
+  uint16_t last_acked_batch_id;
  bool has_data;
 };

--- a/include/meter_driver.h
+++ b/include/meter_driver.h
@@ -1,9 +1,8 @@
 #pragma once

 #include <Arduino.h>
-#include "data_model.h"

 void meter_init();
-bool meter_read(MeterData &data);
-bool meter_poll_frame(const char *&frame, size_t &len);
-bool meter_parse_frame(const char *frame, size_t len, MeterData &data);
+void meter_poll();
+uint8_t meter_count();
+bool meter_get_last_energy_kwh(uint8_t meter_idx, uint32_t &out_energy_kwh);
--- a/src/display_ui.cpp
+++ b/src/display_ui.cpp
@@ -350,9 +350,18 @@ static void render_receiver_sender(uint8_t index) {
 #endif

  display.setCursor(0, 12);
-  display.printf("E %.2f kWh", status.last_data.energy_total_kwh);
+  if (status.last_data.energy_multi) {
+    display.printf("E1 %lu E2 %lu", static_cast<unsigned long>(status.last_data.energy_kwh_int[0]),
+                   static_cast<unsigned long>(status.last_data.energy_kwh_int[1]));
+  } else {
+    display.printf("E %.2f kWh", status.last_data.energy_total_kwh);
+  }
  display.setCursor(0, 22);
-  display.printf("L1 %dW", static_cast<int>(round_power_w(status.last_data.phase_power_w[0])));
+  if (status.last_data.energy_multi && status.last_data.energy_meter_count >= 3) {
+    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);
--- a/src/json_codec.cpp
+++ b/src/json_codec.cpp
@@ -58,16 +58,24 @@ static void set_int_or_null(JsonDocument &doc, const char *key, float 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];
-  format_float_2(buf, sizeof(buf), data.energy_total_kwh);
-  doc["e_kwh"] = serialized(buf);
-  set_int_or_null(doc, "p_w", data.total_power_w);
-  set_int_or_null(doc, "p1_w", data.phase_power_w[0]);
-  set_int_or_null(doc, "p2_w", data.phase_power_w[1]);
-  set_int_or_null(doc, "p3_w", data.phase_power_w[2]);
+  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);
+    set_int_or_null(doc, "p_w", data.total_power_w);
+    set_int_or_null(doc, "p1_w", data.phase_power_w[0]);
+    set_int_or_null(doc, "p2_w", data.phase_power_w[1]);
+    set_int_or_null(doc, "p3_w", data.phase_power_w[2]);
+  }
  format_float_2(buf, sizeof(buf), data.battery_voltage_v);
  doc["bat_v"] = serialized(buf);
  doc["bat_pct"] = data.battery_percent;
@@ -90,5 +98,5 @@ bool meterDataToJson(const MeterData &data, String &out_json) {

  out_json = "";
  size_t len = serializeJson(doc, out_json);
-  return len > 0 && len < 256;
+  return len > 0 && len < 320;
 }
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -55,7 +55,10 @@ 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];
@@ -63,7 +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;
@@ -79,7 +82,7 @@ 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;
@@ -90,10 +93,8 @@ 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 MeterData g_last_meter_data = {};
-static bool g_last_meter_valid = false;
-static uint32_t g_last_meter_rx_ms = 0;
-static uint32_t g_meter_stale_seconds = 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;

@@ -132,6 +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] = {};
@@ -194,7 +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;
  }
@@ -329,33 +331,6 @@ static uint16_t short_id_from_sender_id(uint16_t sender_id) {
  return EXPECTED_SENDER_IDS[sender_id - 1];
 }

-static uint32_t kwh_to_wh_from_float(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 bool float_to_i16_w(float value, int16_t &out) {
-  if (isnan(value)) {
-    out = 0;
-    return true;
-  }
-  long rounded = lroundf(value);
-  if (rounded < INT16_MIN || rounded > INT16_MAX) {
-    return false;
-  }
-  out = static_cast<int16_t>(rounded);
-  return true;
-}
-
 static uint16_t battery_mv_from_voltage(float value) {
  if (isnan(value) || value <= 0.0f) {
    return 0;
@@ -496,6 +471,7 @@ static bool send_inflight_batch(uint32_t ts_for_display) {
    return false;
  }
  BatchInput input = {};
+  input.schema_id = 1;
  input.sender_id = sender_id_from_short_id(g_short_id);
  input.batch_id = g_inflight_batch_id;
  input.t_last = g_inflight_sync_request ? time_get_utc() :
@@ -503,20 +479,17 @@ static bool send_inflight_batch(uint32_t ts_for_display) {
  uint32_t dt_s = METER_SAMPLE_INTERVAL_MS / 1000;
  input.dt_s = dt_s > 0 ? static_cast<uint8_t>(dt_s) : 1;
  input.n = g_inflight_sync_request ? 0 : g_inflight_count;
-  input.battery_mV = g_inflight_sync_request ? battery_mv_from_voltage(g_last_battery_voltage_v) :
-      battery_mv_from_voltage(g_inflight_samples[g_inflight_count - 1].battery_voltage_v);
+  input.meter_count = METER_COUNT;
+  input.battery_mV = battery_mv_from_voltage(g_last_battery_voltage_v);
  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.energy_wh[i] = kwh_to_wh_from_float(g_inflight_samples[i].energy_total_kwh);
-    if (!float_to_i16_w(g_inflight_samples[i].phase_power_w[0], input.p1_w[i]) ||
-        !float_to_i16_w(g_inflight_samples[i].phase_power_w[1], input.p2_w[i]) ||
-        !float_to_i16_w(g_inflight_samples[i].phase_power_w[2], input.p3_w[i])) {
-      return false;
-    }
+    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 encoded[BATCH_MAX_COMPRESSED];
@@ -691,8 +664,10 @@ static bool process_batch_packet(const LoraPacket &pkt, BatchInput &out_batch, b
 }

 void setup() {
-  Serial.begin(115200);
-  delay(200);
+  if (SERIAL_DEBUG_MODE) {
+    Serial.begin(115200);
+    delay(200);
+  }
 #ifdef PAYLOAD_CODEC_TEST
  payload_codec_self_test();
 #endif
@@ -776,63 +751,60 @@ static void sender_loop() {
  }

  if (g_time_acquired) {
-    const char *frame = nullptr;
-    size_t frame_len = 0;
-    if (meter_poll_frame(frame, frame_len)) {
-      MeterData parsed = {};
-      parsed.energy_total_kwh = NAN;
-      parsed.total_power_w = NAN;
-      parsed.phase_power_w[0] = NAN;
-      parsed.phase_power_w[1] = NAN;
-      parsed.phase_power_w[2] = NAN;
-      parsed.valid = false;
-      if (meter_parse_frame(frame, frame_len, parsed)) {
-        g_last_meter_data = parsed;
-        g_last_meter_valid = true;
-        g_last_meter_rx_ms = now_ms;
-        g_meter_stale_seconds = 0;
+    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 = {};
-      data.short_id = g_short_id;
-      strncpy(data.device_id, g_device_id, sizeof(data.device_id));
-
-      bool meter_ok = g_last_meter_valid;
-      if (meter_ok) {
-        data.energy_total_kwh = g_last_meter_data.energy_total_kwh;
-        data.total_power_w = g_last_meter_data.total_power_w;
-        data.phase_power_w[0] = g_last_meter_data.phase_power_w[0];
-        data.phase_power_w[1] = g_last_meter_data.phase_power_w[1];
-        data.phase_power_w[2] = g_last_meter_data.phase_power_w[2];
-        uint32_t age_ms = now_ms - g_last_meter_rx_ms;
-        g_meter_stale_seconds = age_ms >= 1000 ? (age_ms / 1000) : 0;
-      } else {
-        g_meter_stale_seconds++;
+      bool any_meter_valid = false;
+      for (uint8_t i = 0; i < meter_count() && i < 3; ++i) {
+        if (g_last_energy_valid[i]) {
+          any_meter_valid = true;
+          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 {
+        BatchBuffer::EnergySample sample = {};
+        sample.ts_utc = time_get_utc();
+        sample.energy_kwh[0] = g_last_energy_valid[0] ? g_last_energy_kwh[0] : 0;
+        sample.energy_kwh[1] = g_last_energy_valid[1] ? g_last_energy_kwh[1] : 0;
+        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;
+        g_build_samples[g_build_count++] = sample;
+        if (g_build_count >= METER_BATCH_MAX_SAMPLES) {
+          batch_queue_enqueue(g_build_samples, g_build_count);
+          g_build_count = 0;
+        }
+
+        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();
      }
-      data.battery_voltage_v = g_last_battery_voltage_v;
-      data.battery_percent = g_last_battery_percent;
-      data.rx_reject_reason = static_cast<uint8_t>(g_sender_rx_reject_reason);
-      data.ts_utc = time_get_utc();
-      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);
    }

    if (!g_batch_ack_pending && now_ms - g_last_send_ms >= METER_SEND_INTERVAL_MS) {
@@ -1052,11 +1024,24 @@ static void receiver_loop() {
            snprintf(data.device_id, sizeof(data.device_id), "dd3-0000");
          }
          data.ts_utc = t_first + static_cast<uint32_t>(s) * batch.dt_s;
-          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];
+          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;
@@ -1072,6 +1057,7 @@ static void receiver_loop() {
        }

        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) {
            mqtt_publish_state(samples[s]);
--- a/src/meter_driver.cpp
+++ b/src/meter_driver.cpp
@@ -12,20 +12,23 @@ enum class MeterRxState : uint8_t {
  InFrame = 1
 };

-static MeterRxState g_rx_state = MeterRxState::WaitStart;
-static char g_frame_buf[METER_FRAME_MAX + 1];
-static size_t g_frame_len = 0;
-static uint32_t g_last_rx_ms = 0;
-static uint32_t g_bytes_rx = 0;
-static uint32_t g_frames_ok = 0;
-static uint32_t g_frames_parse_fail = 0;
-static uint32_t g_rx_overflow = 0;
-static uint32_t g_rx_timeout = 0;
-static uint32_t g_last_log_ms = 0;
+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;
+};

-void meter_init() {
-  Serial2.begin(9600, SERIAL_7E1, PIN_METER_RX, -1);
-}
+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);
@@ -62,34 +65,30 @@ 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) {
-  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 == ' ') {
+static bool parse_energy_kwh_floor(const char *frame, size_t len, uint32_t &out_kwh) {
+  char line[128];
+  size_t line_len = 0;
+  for (size_t i = 0; i < len; ++i) {
+    char c = frame[i];
+    if (c == '\r') {
      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;
+    if (c == '\n' || c == '!') {
+      line[line_len] = '\0';
+      float value = NAN;
+      if (parse_obis_ascii_value(line, "1-0:1.8.0", value) && !isnan(value) && value >= 0.0f) {
+        out_kwh = static_cast<uint32_t>(floorf(value));
+        return true;
+      }
+      line_len = 0;
+      if (c == '!') {
+        break;
+      }
+      continue;
+    }
+    if (line_len + 1 < sizeof(line)) {
+      line[line_len++] = c;
+    }
  }
  return false;
 }
@@ -103,162 +102,105 @@ static void meter_debug_log() {
    return;
  }
  g_last_log_ms = now_ms;
-  Serial.printf("meter: ok=%lu parse_fail=%lu overflow=%lu timeout=%lu bytes=%lu\n",
-                static_cast<unsigned long>(g_frames_ok),
-                static_cast<unsigned long>(g_frames_parse_fail),
-                static_cast<unsigned long>(g_rx_overflow),
-                static_cast<unsigned long>(g_rx_timeout),
-                static_cast<unsigned long>(g_bytes_rx));
+  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);
+  }
 }

-bool meter_poll_frame(const char *&frame, size_t &len) {
-  frame = nullptr;
-  len = 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;
+  }
+
+  if (METER_COUNT >= 3) {
+    g_ports[2].serial = &Serial;
+    g_ports[2].serial->begin(9600, SERIAL_7E1, PIN_METER3_RX, -1);
+    g_ports[2].state = MeterRxState::WaitStart;
+  }
+}
+
+static void meter_poll_port(MeterPort &port) {
+  if (!port.serial) {
+    return;
+  }
  uint32_t now_ms = millis();
-
-  if (g_rx_state == MeterRxState::InFrame && (now_ms - g_last_rx_ms > METER_FRAME_TIMEOUT_MS)) {
-    g_rx_timeout++;
-    g_rx_state = MeterRxState::WaitStart;
-    g_frame_len = 0;
+  if (port.state == MeterRxState::InFrame && (now_ms - port.last_rx_ms > METER_FRAME_TIMEOUT_MS)) {
+    port.rx_timeout++;
+    port.state = MeterRxState::WaitStart;
+    port.frame_len = 0;
  }

-  while (Serial2.available()) {
-    char c = static_cast<char>(Serial2.read());
-    g_bytes_rx++;
-    g_last_rx_ms = now_ms;
+  while (port.serial->available()) {
+    char c = static_cast<char>(port.serial->read());
+    port.bytes_rx++;
+    port.last_rx_ms = now_ms;

-    if (g_rx_state == MeterRxState::WaitStart) {
+    if (port.state == MeterRxState::WaitStart) {
      if (c == '/') {
-        g_rx_state = MeterRxState::InFrame;
-        g_frame_len = 0;
-        g_frame_buf[g_frame_len++] = c;
+        port.state = MeterRxState::InFrame;
+        port.frame_len = 0;
+        port.frame_buf[port.frame_len++] = c;
      }
      continue;
    }

-    if (g_frame_len + 1 >= sizeof(g_frame_buf)) {
-      g_rx_overflow++;
-      g_rx_state = MeterRxState::WaitStart;
-      g_frame_len = 0;
+    if (port.frame_len + 1 >= sizeof(port.frame_buf)) {
+      port.rx_overflow++;
+      port.state = MeterRxState::WaitStart;
+      port.frame_len = 0;
      continue;
    }

-    g_frame_buf[g_frame_len++] = c;
+    port.frame_buf[port.frame_len++] = c;
    if (c == '!') {
-      g_frame_buf[g_frame_len] = '\0';
-      frame = g_frame_buf;
-      len = g_frame_len;
-      g_rx_state = MeterRxState::WaitStart;
-      g_frame_len = 0;
-      meter_debug_log();
-      return true;
-    }
-  }
-
-  meter_debug_log();
-  return false;
-}
-
-bool meter_parse_frame(const char *frame, size_t len, MeterData &data) {
-  if (!frame || len == 0) {
-    return 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) {
-    char c = frame[i];
-    if (c == '\r') {
-      continue;
-    }
-    if (c == '!') {
-      if (line_len + 1 < sizeof(line)) {
-        line[line_len++] = c;
-      }
-      line[line_len] = '\0';
-      data.valid = energy_ok || total_p_ok || p1_ok || p2_ok || p3_ok;
-      if (data.valid) {
-        g_frames_ok++;
+      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 {
-        g_frames_parse_fail++;
+        port.frames_parse_fail++;
      }
-      return data.valid;
-    }
-    if (c == '\n') {
-      line[line_len] = '\0';
-      if (line[0] == '!') {
-        data.valid = energy_ok || total_p_ok || p1_ok || p2_ok || p3_ok;
-        if (data.valid) {
-          g_frames_ok++;
-        } else {
-          g_frames_parse_fail++;
-        }
-        return data.valid;
-      }
-
-      float value = NAN;
-      if (parse_obis_ascii_value(line, "1-0:1.8.0", value)) {
-        parse_obis_ascii_unit_scale(line, "1-0:1.8.0", value);
-        data.energy_total_kwh = value;
-        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;
-      continue;
-    }
-    if (line_len + 1 < sizeof(line)) {
-      line[line_len++] = c;
+      port.state = MeterRxState::WaitStart;
+      port.frame_len = 0;
    }
  }
-
-  data.valid = got_any;
-  if (data.valid) {
-    g_frames_ok++;
-  } else {
-    g_frames_parse_fail++;
-  }
-  return data.valid;
 }

-bool meter_read(MeterData &data) {
-  data.energy_total_kwh = NAN;
-  data.total_power_w = NAN;
-  data.phase_power_w[0] = NAN;
-  data.phase_power_w[1] = NAN;
-  data.phase_power_w[2] = NAN;
-  data.valid = false;
+void meter_poll() {
+  for (uint8_t i = 0; i < METER_COUNT; ++i) {
+    meter_poll_port(g_ports[i]);
+  }
+  meter_debug_log();
+}

-  const char *frame = nullptr;
-  size_t len = 0;
-  if (!meter_poll_frame(frame, len)) {
+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;
  }
-  return meter_parse_frame(frame, len, data);
+  if (!g_ports[meter_idx].has_energy) {
+    return false;
+  }
+  out_energy_kwh = g_ports[meter_idx].last_energy_kwh;
+  return true;
 }
--- a/src/payload_codec.cpp
+++ b/src/payload_codec.cpp
@@ -5,6 +5,8 @@ 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);
@@ -108,13 +110,14 @@ bool encode_batch(const BatchInput &in, uint8_t *out, size_t out_cap, size_t *ou
    return false;
  }
  size_t pos = 0;
-  if (!ensure_capacity(21, out_cap, pos)) {
+  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);
@@ -130,12 +133,32 @@ bool encode_batch(const BatchInput &in, uint8_t *out, size_t out_cap, size_t *ou
  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;
  }
@@ -189,7 +212,7 @@ bool decode_batch(const uint8_t *buf, size_t len, BatchInput *out) {
    return false;
  }
  size_t pos = 0;
-  if (len < 21) {
+  if (len < 23) {
    return false;
  }
  uint16_t magic = read_u16_le(&buf[pos]);
@@ -199,6 +222,7 @@ bool decode_batch(const uint8_t *buf, size_t len, BatchInput *out) {
  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]);
@@ -214,6 +238,7 @@ bool decode_batch(const uint8_t *buf, size_t len, BatchInput *out) {
  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;
@@ -227,6 +252,29 @@ bool decode_batch(const uint8_t *buf, size_t len, BatchInput *out) {
    }
    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;
  }
@@ -289,6 +337,7 @@ bool decode_batch(const uint8_t *buf, size_t len, BatchInput *out) {
 #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;
@@ -300,6 +349,7 @@ bool payload_codec_self_test() {
  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;
--- a/src/payload_codec.h
+++ b/src/payload_codec.h
@@ -3,17 +3,22 @@
 #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];
--- a/src/test_mode.cpp
+++ b/src/test_mode.cpp
@@ -12,8 +12,93 @@

 static uint32_t g_last_test_ms = 0;
 static uint16_t g_test_code_counter = 1000;
+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 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 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;
@@ -36,11 +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);
@@ -60,11 +147,32 @@ void test_sender_loop(uint16_t short_id, const char *device_id) {
  pkt.device_id_short = short_id;
  pkt.payload_len = json.length();
  memcpy(pkt.payload, json.c_str(), pkt.payload_len);
-  lora_send(pkt);
+  if (!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) {
-  (void)self_short_id;
  LoraPacket pkt = {};
  if (!lora_receive(pkt, 0)) {
    return;
@@ -73,22 +181,28 @@ void test_receiver_loop(SenderStatus *statuses, uint8_t count, uint16_t self_sho
    return;
  }

-  uint8_t decompressed[160];
+  uint8_t decompressed[192];
  if (pkt.payload_len >= sizeof(decompressed)) {
    return;
  }
  memcpy(decompressed, pkt.payload, pkt.payload_len);
  decompressed[pkt.payload_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);
@@ -96,12 +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
--- a/src/web_server.cpp
+++ b/src/web_server.cpp
@@ -363,6 +363,7 @@ static String render_sender_block(const SenderStatus &status) {
    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)) + ")";
@@ -374,11 +375,19 @@ static String render_sender_block(const SenderStatus &status) {
  if (!status.has_data) {
    s += "No data";
  } 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>";
+    if (status.last_data.energy_multi) {
+      s += "Energy1: " + String(status.last_data.energy_kwh_int[0]) + " kWh<br>";
+      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>";
@@ -605,14 +614,16 @@ static void handle_sender() {
      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><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, 2) + "</td>";
+          html += "<td>" + String(d.energy_kwh_int[0]) + "</td>";
+          html += "<td>" + String(d.energy_kwh_int[1]) + "</td>";
+          html += "<td>" + String(d.energy_kwh_int[2]) + "</td>";
          html += "<td>" + String(round_power_w(d.total_power_w)) + "</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>";
Author	SHA1	Message	Date
acidburns	eb80f49046	test: align test mode with ACK/time flow and expose ack metrics	2026-02-04 20:12:02 +01:00
acidburns	31a3eea5dd	docs: rewrite README for current multi-meter behavior	2026-02-04 19:03:43 +01:00
acidburns	c62f07bf44	Document multi-meter UART mapping and energy-only sender behavior	2026-02-04 15:22:30 +01:00
acidburns	938f490a32	Add multi-meter energy sender schema with UART0/1/2 mode split	2026-02-04 15:22:24 +01:00