document batching updates and restore bat_v in batches

README.md

@@ -59,7 +59,7 @@ void sender_loop() {
   read_battery(data);        // VBAT + SoC
 
   if (time_to_send_batch()) {
-    json = meterBatchToJson(samples, batch_id);
+    json = meterBatchToJson(samples, batch_id); // bat_v per batch, t_first/t_last included
     compressed = compressBuffer(json);
     lora_send(packet(MeterBatch, compressed));
   }
@@ -92,7 +92,7 @@ bool lora_send(const LoraPacket &pkt);   // add header + CRC16 and transmit
 - Web UI:
   - AP mode: status + WiFi/MQTT config.
   - STA mode: status + per-sender pages.
-- OLED cycles through receiver status and per-sender pages.
+- OLED cycles through receiver status and per-sender pages (receiver OLED never sleeps).
 
 **Receiver loop (pseudo-code)**:
 ```cpp
@@ -106,7 +106,7 @@ void receiver_loop() {
       }
     } else if (pkt.type == MeterBatch) {
       json = reassemble_and_decompress_batch(pkt);
-      for (sample in jsonToMeterBatch(json)) {
+      for (sample in jsonToMeterBatch(json)) { // uses t_first/t_last for jittered timestamps
         update_sender_status(sample);
         mqtt_publish_state(sample);
       }
@@ -176,7 +176,7 @@ Packet layout:
 
 LoRa radio settings:
 - Frequency: **433 MHz** or **868 MHz** (set by build env via `LORA_FREQUENCY_HZ`)
-- SF12, BW 125 kHz, CR 4/5, CRC on, Sync Word 0x34
+- SF10, BW 125 kHz, CR 4/5, CRC on, Sync Word 0x34
 
 ## Data Format
 JSON payload (sender + MQTT):
@@ -203,6 +203,8 @@ MeterBatch JSON (compressed over LoRa) uses per-field arrays with integer units
   "sender": "s01",
   "batch_id": 1842,
   "t0": 1738288000,
+  "t_first": 1738288000,
+  "t_last": 1738288030,
   "dt_s": 1,
   "n": 3,
   "energy_wh": [123456700, 123456701, 123456701],
@@ -210,6 +212,7 @@ MeterBatch JSON (compressed over LoRa) uses per-field arrays with integer units
   "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,
@@ -221,6 +224,7 @@ MeterBatch JSON (compressed over LoRa) uses per-field arrays with integer units
 Notes:
 - `sender` maps to `EXPECTED_SENDER_IDS` order (`s01` = first sender).
 - `meta` is injected by the receiver after batch reassembly.
+- `bat_v` is a single batch-level value (percent is calculated locally).
 
 ## Device IDs
 - Derived from WiFi STA MAC.
@@ -236,9 +240,7 @@ inline constexpr uint16_t EXPECTED_SENDER_IDS[NUM_SENDERS] = { 0xF19C };
 
 ## OLED Behavior
 - Sender: OLED stays **ON for 10 seconds** on each wake, then powers down for sleep.
-- Receiver: OLED follows the 10-minute auto-off behavior:
-  - GPIO14 HIGH: OLED forced ON.
-  - GPIO14 LOW: auto-off after 10 minutes.
+- Receiver: OLED is always on (no auto-off).
 - Pages rotate every 4s.
 
 ## Power & Battery
@@ -283,6 +285,10 @@ Key timing settings in `include/config.h`:
 - `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
 - **Compression**: uses lightweight RLE (good for JSON but not optimal).

include/config.h

@@ -73,8 +73,8 @@ 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 = true;
-constexpr bool SERIAL_DEBUG_DUMP_JSON = true;
+constexpr bool SERIAL_DEBUG_MODE = false;
+constexpr bool SERIAL_DEBUG_DUMP_JSON = false;
 constexpr bool LORA_SEND_BYPASS = false;
 
 constexpr uint8_t NUM_SENDERS = 1;

src/json_codec.cpp

@@ -199,6 +199,11 @@ bool meterBatchToJson(const MeterData *samples, size_t count, uint16_t batch_id,
   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("energy_wh");
   JsonArray p_w = doc.createNestedArray("p_w");
@@ -235,6 +240,7 @@ bool jsonToMeterBatch(const String &json, MeterData *out_samples, size_t max_cou
   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) {
@@ -284,8 +290,12 @@ bool jsonToMeterBatch(const String &json, MeterData *out_samples, size_t max_cou
       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 = NAN;
+      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;