Refactor LoRa protocol to batch+ack with ACK-based time bootstrap

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;
@@ -57,17 +47,7 @@ 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 TIME_SYNC_SLOW_INTERVAL_SEC = 3600;
-constexpr uint32_t TIME_SYNC_FAST_WINDOW_MS = 10UL * 60UL * 1000UL;
-constexpr uint32_t SENDER_TIMESYNC_WINDOW_MS = 300;
-constexpr uint32_t SENDER_TIMESYNC_CHECK_SEC_FAST = 60;
-constexpr uint32_t SENDER_TIMESYNC_CHECK_SEC_SLOW = 3600;
-constexpr uint32_t TIME_SYNC_DRIFT_THRESHOLD_SEC = 10;
-constexpr uint32_t TIME_SYNC_BURST_INTERVAL_MS = 10000;
-constexpr uint32_t TIME_SYNC_BURST_DURATION_MS = 10UL * 60UL * 1000UL;
-constexpr uint32_t TIME_SYNC_ERROR_TIMEOUT_MS = 2UL * 24UL * 60UL * 60UL * 1000UL;
-constexpr bool ENABLE_DS3231 = true;
+constexpr uint32_t SYNC_REQUEST_INTERVAL_MS = 15000;
 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;
@@ -107,6 +87,7 @@ 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

@@ -6,19 +6,16 @@ enum class FaultType : uint8_t {
   None = 0,
   MeterRead = 1,
   Decode = 2,
-  LoraTx = 3,
-  TimeSync = 4
+  LoraTx = 3
 };
 
 enum class RxRejectReason : uint8_t {
   None = 0,
   CrcFail = 1,
-  BadProtocol = 2,
-  WrongRole = 3,
-  WrongPayloadType = 4,
-  LengthMismatch = 5,
-  DeviceIdMismatch = 6,
-  BatchIdMismatch = 7
+  InvalidMsgKind = 2,
+  LengthMismatch = 3,
+  DeviceIdMismatch = 4,
+  BatchIdMismatch = 5
 };
 
 struct FaultCounters {

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

@@ -6,11 +6,14 @@
 
 constexpr size_t LORA_MAX_PAYLOAD = 230;
 
+enum class LoraMsgKind : uint8_t {
+  BatchUp = 0,
+  AckDown = 1
+};
+
 struct LoraPacket {
-  uint8_t protocol_version;
-  DeviceRole role;
+  LoraMsgKind msg_kind;
   uint16_t device_id_short;
-  PayloadType payload_type;
   uint8_t payload[LORA_MAX_PAYLOAD];
   size_t payload_len;
   int16_t rssi_dbm;

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();