Add IEC62056 parsing, OLED timing, and batch LoRa send

README.md

@@ -36,7 +36,7 @@ Variants:
 
 ## Firmware Roles
 ### Sender (battery-powered)
-- Reads DD3 smart meter via optical IR (UART 9600 7E1).
+- Reads smart meter via optical IR (UART 9600 7E1).
 - Extracts OBIS values:
   - Energy total: 1-0:1.8.0*255
   - Total power: 1-0:16.7.0*255
@@ -65,6 +65,7 @@ void sender_cycle() {
   display_tick();
 
   lora_receive_time_sync(); // optional
+  keep_oled_on_for_read_window();
   deep_sleep(SENDER_WAKE_INTERVAL_SEC);
 }
 ```
@@ -195,11 +196,11 @@ inline constexpr uint16_t EXPECTED_SENDER_IDS[NUM_SENDERS] = { 0xF19C };
 ```
 
 ## OLED Behavior
-- After reset, OLED stays **ON for 10 minutes** regardless of switch.
-- After that:
+- 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: start 10-minute auto-off timer.
-- Pages rotate every 10s.
+  - GPIO14 LOW: auto-off after 10 minutes.
+- Pages rotate every 4s.
 
 ## Power & Battery
 - Sender disables WiFi/BLE, reads VBAT via ADC, uses linear SoC map:
@@ -233,7 +234,7 @@ inline constexpr uint16_t EXPECTED_SENDER_IDS[NUM_SENDERS] = { 0xF19C };
 
 ## Limits & Known Constraints
 - **Compression**: uses lightweight RLE (good for JSON but not optimal).
-- **OBIS parsing**: heuristic SML parser; may need tuning for some DD3 meters.
+- **OBIS parsing**: supports IEC 62056-21 ASCII (Mode D) and SML; may need tuning for some meters.
 - **Payload size**: JSON < 256 bytes (enforced by ArduinoJson static doc).
 - **Battery ADC**: uses simple linear calibration constant in `power_manager.cpp`.
 - **OLED**: no hardware reset line is used (matches working reference).
@@ -244,7 +245,7 @@ inline constexpr uint16_t EXPECTED_SENDER_IDS[NUM_SENDERS] = { 0xF19C };
 - `include/json_codec.h`, `src/json_codec.cpp`: JSON encode/decode
 - `include/compressor.h`, `src/compressor.cpp`: RLE compression
 - `include/lora_transport.h`, `src/lora_transport.cpp`: LoRa packet + CRC
-- `include/meter_driver.h`, `src/meter_driver.cpp`: SML/OBIS parse
+- `include/meter_driver.h`, `src/meter_driver.cpp`: IEC 62056-21 ASCII + SML parse
 - `include/power_manager.h`, `src/power_manager.cpp`: ADC + sleep
 - `include/time_manager.h`, `src/time_manager.cpp`: NTP + time sync
 - `include/wifi_manager.h`, `src/wifi_manager.cpp`: NVS config + WiFi