89 lines
2.2 KiB
Markdown
89 lines
2.2 KiB
Markdown
# DD3-LoRa-Bridge-MultiSender
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Unified firmware for LilyGO T3 v1.6.1 (ESP32 + SX1276 + SSD1306) running as either:
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- `Sender`: reads meter values and sends binary batches over LoRa.
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- `Receiver`: accepts batches, ACKs with optional time, publishes to MQTT/web.
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## Protocol (minimal)
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Frame format:
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`[msg_kind:1][dev_id_short:2][payload...][crc16:2]`
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`msg_kind`:
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- `0`: `BATCH_UP` (Sender -> Receiver)
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- `1`: `ACK_DOWN` (Receiver -> Sender)
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Removed from protocol:
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- protocol version field
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- payload type field
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- MeterData JSON/compressed LoRa path
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- standalone TimeSync packets
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CRC16 validation is still required on every frame.
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## Payloads
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### 1) `BATCH_UP`
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- Uses existing binary batch/chunk transport.
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- `sample_count == 0` is valid and means `SYNC_REQUEST`.
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### 2) `ACK_DOWN` (7 bytes)
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- `flags` (`u8`): bit0 = `time_valid`
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- `batch_id` (`u16`, big-endian)
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- `epoch_utc` (`u32`, big-endian)
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Receiver sets:
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- `time_valid=1` only when receiver time is authoritative and sane.
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- Otherwise `time_valid=0` and `epoch_utc=0`.
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## Time bootstrap safety
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Sender starts with:
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- `g_time_acquired=false`
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- no real sampling/batching
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- periodic `SYNC_REQUEST` every `SYNC_REQUEST_INTERVAL_MS` (default `15000ms`)
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Sender only accepts time from `ACK_DOWN` if:
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- `time_valid == 1`
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- `epoch_utc >= 2026-02-01 00:00:00 UTC` (`MIN_ACCEPTED_EPOCH_UTC = 1769904000`)
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Only then:
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- system time is set
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- `g_time_acquired=true`
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- normal 1 Hz sampling + batch transmit starts
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This guarantees no pre-`2026-02-01` epoch reaches MQTT or SD/DB paths.
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## Receiver behavior
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On `BATCH_UP`:
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1. Decode batch/chunks.
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2. Send `ACK_DOWN` immediately.
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3. If `sample_count == 0`: treat as `SYNC_REQUEST`, do not publish MQTT/update stats.
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4. Else decode and publish samples as normal.
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## Sender/Receiver debug logs (`SERIAL_DEBUG_MODE`)
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Sender:
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- `sync: request tx batch_id=%u`
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- `ack: rx ok batch_id=%u time_valid=%u epoch=%lu set=%u`
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- `ack: timeout batch_id=%u retry=%u`
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Receiver:
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- `ack: tx batch_id=%u time_valid=%u epoch=%lu samples=%u`
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## Removed hardware dependency
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DS3231 RTC support was removed:
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- no RTC files
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- no RTC init/load/set logic
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- no `ENABLE_DS3231` flow
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## Build
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```bash
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pio run -e lilygo-t3-v1-6-1
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pio run -e lilygo-t3-v1-6-1-test
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```
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