128 lines
3.9 KiB
Markdown
128 lines
3.9 KiB
Markdown
# DD3-LoRa-Bridge-MultiSender
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Firmware for LilyGO T3 v1.6.1 (`ESP32 + SX1276 + SSD1306`) that runs as either:
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- `Sender` (PIN `GPIO14` HIGH): reads one IEC 62056-21 meter, batches samples, sends over LoRa.
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- `Receiver` (PIN `GPIO14` LOW): receives/ACKs batches, publishes MQTT, serves web UI, logs to SD.
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## Current Architecture
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- Single codebase, role selected at boot via `detect_role()` (`include/config.h`, `src/config.cpp`).
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- LoRa link uses explicit CRC16 frame protection in firmware (`src/lora_transport.cpp`).
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- Sender batches up to `30` samples and retries on missing ACK (`BATCH_MAX_RETRIES=2`, retry policy `Keep`).
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- Receiver uses STA mode when config is valid, otherwise AP fallback with web config.
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## LoRa Frame Protocol (Current)
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On-air frame format:
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`[msg_kind:1][device_short_id:2][payload...][crc16:2]`
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`msg_kind`:
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- `0` = `BatchUp`
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- `1` = `AckDown`
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### `BatchUp`
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Transport is chunked (`batch_id`, `chunk_index`, `chunk_count`, `total_len`) and reassembled before payload decode.
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Payload codec (`src/payload_codec.cpp`) currently uses:
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- `kMagic=0xDDB3`
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- `kSchema=2`
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- metadata: sender, batch, timestamp, interval, battery, fault counters
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- data arrays: `energy_wh[]`, `p1_w[]`, `p2_w[]`, `p3_w[]`
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`n == 0` is valid and used for sync request packets.
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### `AckDown` (7 bytes)
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`[flags:1][batch_id_be:2][epoch_utc_be:4]`
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- `flags bit0`: `time_valid`
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- Receiver repeats ACK (`ACK_REPEAT_COUNT=3`, `ACK_REPEAT_DELAY_MS=200`).
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- Sender accepts time only if `time_valid=1` and `epoch >= MIN_ACCEPTED_EPOCH_UTC` (`2026-02-01 00:00:00 UTC`).
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## Time Bootstrap Guardrail
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On sender boot:
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- `g_time_acquired=false`
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- no normal sampling/transmit yet
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- sync request every `SYNC_REQUEST_INTERVAL_MS` (15s)
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Only after valid ACK time is received:
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- system time is set
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- normal 1 Hz sampling and periodic LoRa batch transmit start
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This blocks pre-threshold timestamps from MQTT/SD paths.
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## Sender Meter Path
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Implemented in `src/meter_driver.cpp` + sender loop in `src/main.cpp`:
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- UART: `Serial2`, RX pin `GPIO34` (`PIN_METER_RX`), `9600 7E1`
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- Frame detection: starts at `'/'`, ends at `'!'`, timeout protection included
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- Parsed OBIS values:
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- `1-0:1.8.0` (total energy)
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- `1-0:16.7.0` (total power)
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- `1-0:36.7.0`, `56.7.0`, `76.7.0` (phase powers)
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- `1-0:1.8.0*Wh` is automatically scaled to kWh
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Sender samples every second and transmits batches every 30 seconds.
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## Receiver Behavior
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For valid `BatchUp` decode:
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1. Reassemble chunks and decode payload.
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2. Send `AckDown` immediately.
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3. Drop duplicate batches per sender (`batch_id` tracking).
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4. If `n==0`: treat as sync request only.
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5. Else convert samples, log to SD, update web UI, publish MQTT.
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## MQTT Topics and Payloads
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State topic:
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- `smartmeter/<device_id>/state`
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Fault topic (retained):
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- `smartmeter/<device_id>/faults`
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State JSON fields (`src/json_codec.cpp`):
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- `id`, `ts`, `e_kwh`
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- `p_w`, `p1_w`, `p2_w`, `p3_w`
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- `bat_v`, `bat_pct`
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- optional link fields: `rssi`, `snr`
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- fault/reject fields: `err_last`, `rx_reject`, `rx_reject_text` (+ non-zero counters)
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Home Assistant discovery is enabled (`ENABLE_HA_DISCOVERY=true`) and publishes config topics under:
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- `homeassistant/sensor/<device_id>/<key>/config`
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## Web UI, Wi-Fi, Storage
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- Wi-Fi/MQTT/NTP/web-auth config persists in Preferences (`wifi_manager`).
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- AP fallback SSID prefix: `DD3-Bridge-`.
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- Default web credentials: `admin/admin`.
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- SD logging enabled (`ENABLE_SD_LOGGING=true`).
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## Build Environments
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From `platformio.ini`:
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- `lilygo-t3-v1-6-1`
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- `lilygo-t3-v1-6-1-test`
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- `lilygo-t3-v1-6-1-868`
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- `lilygo-t3-v1-6-1-868-test`
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- `lilygo-t3-v1-6-1-payload-test`
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- `lilygo-t3-v1-6-1-868-payload-test`
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- `lilygo-t3-v1-6-1-prod`
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- `lilygo-t3-v1-6-1-868-prod`
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Example:
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```bash
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~/.platformio/penv/bin/pio run -e lilygo-t3-v1-6-1
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```
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## Test Mode
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`ENABLE_TEST_MODE` replaces normal sender/receiver loops with dedicated test loops (`src/test_mode.cpp`).
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It sends/receives JSON test frames and publishes to `smartmeter/<device_id>/test`.
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