Add IEC62056 parsing, OLED timing, and batch LoRa send

2026-01-28 01:22:13 +01:00
parent 449fff1f06
commit e480677b49
8 changed files with 570 additions and 65 deletions
--- a/README.md
+++ b/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
--- a/include/config.h
+++ b/include/config.h
@@ -10,7 +10,8 @@ enum class DeviceRole : uint8_t {
 enum class PayloadType : uint8_t {
  MeterData = 0,
  TestCode = 1,
-  TimeSync = 2
+  TimeSync = 2,
+  MeterBatch = 3
 };

 constexpr uint8_t PROTOCOL_VERSION = 1;
@@ -53,6 +54,9 @@ constexpr uint32_t TIME_SYNC_INTERVAL_SEC = 60;
 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;
+constexpr uint32_t METER_SAMPLE_INTERVAL_MS = 1000;
+constexpr uint32_t METER_SEND_INTERVAL_MS = 30000;
+constexpr uint8_t METER_BATCH_MAX_SAMPLES = 30;

 constexpr uint8_t NUM_SENDERS = 1;
 inline constexpr uint16_t EXPECTED_SENDER_IDS[NUM_SENDERS] = {
--- a/include/json_codec.h
+++ b/include/json_codec.h
@@ -5,3 +5,5 @@

 bool meterDataToJson(const MeterData &data, String &out_json);
 bool jsonToMeterData(const String &json, MeterData &data);
+bool meterBatchToJson(const MeterData *samples, size_t count, String &out_json);
+bool jsonToMeterBatch(const String &json, MeterData *out_samples, size_t max_count, size_t &out_count);
--- a/include/power_manager.h
+++ b/include/power_manager.h
@@ -7,4 +7,5 @@ void power_sender_init();
 void power_receiver_init();
 void read_battery(MeterData &data);
 uint8_t battery_percent_from_voltage(float voltage_v);
+void light_sleep_ms(uint32_t ms);
 void go_to_deep_sleep(uint32_t seconds);
--- a/src/json_codec.cpp
+++ b/src/json_codec.cpp
@@ -59,3 +59,90 @@ bool jsonToMeterData(const String &json, MeterData &data) {

  return true;
 }
+
+bool meterBatchToJson(const MeterData *samples, size_t count, String &out_json) {
+  if (!samples || count == 0) {
+    return false;
+  }
+
+  DynamicJsonDocument doc(8192);
+  doc["id"] = samples[count - 1].device_id;
+  doc["bat_v"] = samples[count - 1].battery_voltage_v;
+  doc["bat_pct"] = samples[count - 1].battery_percent;
+  JsonArray arr = doc.createNestedArray("s");
+  for (size_t i = 0; i < count; ++i) {
+    JsonArray row = arr.createNestedArray();
+    row.add(samples[i].ts_utc);
+    row.add(samples[i].energy_total_kwh);
+    row.add(samples[i].total_power_w);
+    row.add(samples[i].phase_power_w[0]);
+    row.add(samples[i].phase_power_w[1]);
+    row.add(samples[i].phase_power_w[2]);
+    row.add(samples[i].phase_voltage_v[0]);
+    row.add(samples[i].phase_voltage_v[1]);
+    row.add(samples[i].phase_voltage_v[2]);
+    row.add(samples[i].valid ? 1 : 0);
+  }
+
+  out_json = "";
+  size_t len = serializeJson(doc, out_json);
+  return len > 0;
+}
+
+bool jsonToMeterBatch(const String &json, MeterData *out_samples, size_t max_count, size_t &out_count) {
+  out_count = 0;
+  if (!out_samples || max_count == 0) {
+    return false;
+  }
+
+  DynamicJsonDocument doc(8192);
+  DeserializationError err = deserializeJson(doc, json);
+  if (err) {
+    return false;
+  }
+
+  JsonArray arr = doc["s"].as<JsonArray>();
+  if (arr.isNull()) {
+    return false;
+  }
+
+  const char *id = doc["id"] | "";
+  float bat_v = doc["bat_v"] | NAN;
+  uint8_t bat_pct = doc["bat_pct"] | 0;
+
+  size_t idx = 0;
+  for (JsonArray row : arr) {
+    if (idx >= max_count) {
+      break;
+    }
+    MeterData &data = out_samples[idx];
+    data = {};
+    strncpy(data.device_id, id, sizeof(data.device_id));
+    data.device_id[sizeof(data.device_id) - 1] = '\0';
+    data.ts_utc = row[0] | 0;
+    data.energy_total_kwh = row[1] | NAN;
+    data.total_power_w = row[2] | NAN;
+    data.phase_power_w[0] = row[3] | NAN;
+    data.phase_power_w[1] = row[4] | NAN;
+    data.phase_power_w[2] = row[5] | NAN;
+    data.phase_voltage_v[0] = row[6] | NAN;
+    data.phase_voltage_v[1] = row[7] | NAN;
+    data.phase_voltage_v[2] = row[8] | NAN;
+    data.valid = (row[9] | 1) != 0;
+    data.battery_voltage_v = bat_v;
+    if (doc["bat_pct"].isNull() && !isnan(bat_v)) {
+      data.battery_percent = battery_percent_from_voltage(bat_v);
+    } else {
+      data.battery_percent = bat_pct;
+    }
+
+    if (strlen(data.device_id) >= 8) {
+      const char *suffix = data.device_id + strlen(data.device_id) - 4;
+      data.short_id = static_cast<uint16_t>(strtoul(suffix, nullptr, 16));
+    }
+    idx++;
+  }
+
+  out_count = idx;
+  return idx > 0;
+}
--- a/src/main.cpp
+++ b/src/main.cpp
@@ -23,6 +23,32 @@ static WifiMqttConfig g_cfg;
 static uint32_t g_last_timesync_ms = 0;
 static constexpr uint32_t TIME_SYNC_OFFSET_MS = 15000;

+static constexpr size_t BATCH_HEADER_SIZE = 6;
+static constexpr size_t BATCH_CHUNK_PAYLOAD = LORA_MAX_PAYLOAD - BATCH_HEADER_SIZE;
+static constexpr size_t BATCH_MAX_COMPRESSED = 4096;
+static constexpr size_t BATCH_MAX_DECOMPRESSED = 8192;
+static constexpr uint32_t BATCH_RX_TIMEOUT_MS = 2000;
+
+static MeterData g_meter_samples[METER_BATCH_MAX_SAMPLES];
+static uint8_t g_meter_sample_count = 0;
+static uint8_t g_meter_sample_head = 0;
+static uint32_t g_last_sample_ms = 0;
+static uint32_t g_last_send_ms = 0;
+static uint16_t g_batch_id = 1;
+
+struct BatchRxState {
+  bool active;
+  uint16_t batch_id;
+  uint8_t next_index;
+  uint8_t expected_chunks;
+  uint16_t total_len;
+  uint16_t received_len;
+  uint32_t last_rx_ms;
+  uint8_t buffer[BATCH_MAX_COMPRESSED];
+};
+
+static BatchRxState g_batch_rx = {};
+
 static void init_sender_statuses() {
  for (uint8_t i = 0; i < NUM_SENDERS; ++i) {
    g_sender_statuses[i] = {};
@@ -33,6 +59,187 @@ static void init_sender_statuses() {
  }
 }

+static void push_meter_sample(const MeterData &data) {
+  g_meter_samples[g_meter_sample_head] = data;
+  g_meter_sample_head = (g_meter_sample_head + 1) % METER_BATCH_MAX_SAMPLES;
+  if (g_meter_sample_count < METER_BATCH_MAX_SAMPLES) {
+    g_meter_sample_count++;
+  }
+}
+
+static size_t copy_meter_samples(MeterData *out, size_t max_count) {
+  if (!out || max_count == 0 || g_meter_sample_count == 0) {
+    return 0;
+  }
+  size_t count = g_meter_sample_count < max_count ? g_meter_sample_count : max_count;
+  size_t start = (g_meter_sample_head + METER_BATCH_MAX_SAMPLES - count) % METER_BATCH_MAX_SAMPLES;
+  for (size_t i = 0; i < count; ++i) {
+    out[i] = g_meter_samples[(start + i) % METER_BATCH_MAX_SAMPLES];
+  }
+  return count;
+}
+
+static uint32_t last_sample_ts() {
+  if (g_meter_sample_count == 0) {
+    uint32_t now_utc = time_get_utc();
+    return now_utc > 0 ? now_utc : millis() / 1000;
+  }
+  size_t idx = (g_meter_sample_head + METER_BATCH_MAX_SAMPLES - 1) % METER_BATCH_MAX_SAMPLES;
+  return g_meter_samples[idx].ts_utc;
+}
+
+static void write_u16_le(uint8_t *dst, uint16_t value) {
+  dst[0] = static_cast<uint8_t>(value & 0xFF);
+  dst[1] = static_cast<uint8_t>((value >> 8) & 0xFF);
+}
+
+static uint16_t read_u16_le(const uint8_t *src) {
+  return static_cast<uint16_t>(src[0]) | (static_cast<uint16_t>(src[1]) << 8);
+}
+
+static bool send_batch_payload(const uint8_t *data, size_t len, uint32_t ts_for_display) {
+  if (!data || len == 0 || len > BATCH_MAX_COMPRESSED) {
+    return false;
+  }
+  uint8_t chunk_count = static_cast<uint8_t>((len + BATCH_CHUNK_PAYLOAD - 1) / BATCH_CHUNK_PAYLOAD);
+  if (chunk_count == 0) {
+    return false;
+  }
+
+  bool all_ok = true;
+  size_t offset = 0;
+  for (uint8_t i = 0; i < chunk_count; ++i) {
+    size_t chunk_len = len - offset;
+    if (chunk_len > BATCH_CHUNK_PAYLOAD) {
+      chunk_len = BATCH_CHUNK_PAYLOAD;
+    }
+    LoraPacket pkt = {};
+    pkt.protocol_version = PROTOCOL_VERSION;
+    pkt.role = DeviceRole::Sender;
+    pkt.device_id_short = g_short_id;
+    pkt.payload_type = PayloadType::MeterBatch;
+    pkt.payload_len = chunk_len + BATCH_HEADER_SIZE;
+
+    uint8_t *payload = pkt.payload;
+    write_u16_le(&payload[0], g_batch_id);
+    payload[2] = i;
+    payload[3] = chunk_count;
+    write_u16_le(&payload[4], static_cast<uint16_t>(len));
+    memcpy(&payload[BATCH_HEADER_SIZE], data + offset, chunk_len);
+
+    bool ok = lora_send(pkt);
+    all_ok = all_ok && ok;
+    offset += chunk_len;
+    delay(10);
+  }
+
+  if (all_ok) {
+    g_batch_id++;
+  }
+  display_set_last_tx(all_ok, ts_for_display);
+  return all_ok;
+}
+
+static bool send_meter_batch(uint32_t ts_for_display) {
+  MeterData ordered[METER_BATCH_MAX_SAMPLES];
+  size_t count = copy_meter_samples(ordered, METER_BATCH_MAX_SAMPLES);
+  if (count == 0) {
+    return false;
+  }
+
+  String json;
+  if (!meterBatchToJson(ordered, count, json)) {
+    return false;
+  }
+
+  static uint8_t compressed[BATCH_MAX_COMPRESSED];
+  size_t compressed_len = 0;
+  if (!compressBuffer(reinterpret_cast<const uint8_t *>(json.c_str()), json.length(), compressed, sizeof(compressed), compressed_len)) {
+    return false;
+  }
+
+  bool ok = send_batch_payload(compressed, compressed_len, ts_for_display);
+  if (ok) {
+    g_meter_sample_count = 0;
+    g_meter_sample_head = 0;
+  }
+  return ok;
+}
+
+static void reset_batch_rx() {
+  g_batch_rx.active = false;
+  g_batch_rx.batch_id = 0;
+  g_batch_rx.next_index = 0;
+  g_batch_rx.expected_chunks = 0;
+  g_batch_rx.total_len = 0;
+  g_batch_rx.received_len = 0;
+  g_batch_rx.last_rx_ms = 0;
+}
+
+static bool process_batch_packet(const LoraPacket &pkt, String &out_json) {
+  if (pkt.payload_len < BATCH_HEADER_SIZE) {
+    return false;
+  }
+  uint16_t batch_id = read_u16_le(&pkt.payload[0]);
+  uint8_t chunk_index = pkt.payload[2];
+  uint8_t chunk_count = pkt.payload[3];
+  uint16_t total_len = read_u16_le(&pkt.payload[4]);
+  const uint8_t *chunk_data = &pkt.payload[BATCH_HEADER_SIZE];
+  size_t chunk_len = pkt.payload_len - BATCH_HEADER_SIZE;
+  uint32_t now_ms = millis();
+
+  if (!g_batch_rx.active || batch_id != g_batch_rx.batch_id || (now_ms - g_batch_rx.last_rx_ms > BATCH_RX_TIMEOUT_MS)) {
+    if (chunk_index != 0) {
+      reset_batch_rx();
+      return false;
+    }
+    if (total_len == 0 || total_len > BATCH_MAX_COMPRESSED || chunk_count == 0) {
+      reset_batch_rx();
+      return false;
+    }
+    g_batch_rx.active = true;
+    g_batch_rx.batch_id = batch_id;
+    g_batch_rx.expected_chunks = chunk_count;
+    g_batch_rx.total_len = total_len;
+    g_batch_rx.received_len = 0;
+    g_batch_rx.next_index = 0;
+  }
+
+  if (!g_batch_rx.active || chunk_index != g_batch_rx.next_index || chunk_count != g_batch_rx.expected_chunks) {
+    reset_batch_rx();
+    return false;
+  }
+
+  if (g_batch_rx.received_len + chunk_len > g_batch_rx.total_len || g_batch_rx.received_len + chunk_len > BATCH_MAX_COMPRESSED) {
+    reset_batch_rx();
+    return false;
+  }
+
+  memcpy(&g_batch_rx.buffer[g_batch_rx.received_len], chunk_data, chunk_len);
+  g_batch_rx.received_len += static_cast<uint16_t>(chunk_len);
+  g_batch_rx.next_index++;
+  g_batch_rx.last_rx_ms = now_ms;
+
+  if (g_batch_rx.next_index == g_batch_rx.expected_chunks && g_batch_rx.received_len == g_batch_rx.total_len) {
+    static uint8_t decompressed[BATCH_MAX_DECOMPRESSED];
+    size_t decompressed_len = 0;
+    if (!decompressBuffer(g_batch_rx.buffer, g_batch_rx.received_len, decompressed, sizeof(decompressed) - 1, decompressed_len)) {
+      reset_batch_rx();
+      return false;
+    }
+    if (decompressed_len >= sizeof(decompressed)) {
+      reset_batch_rx();
+      return false;
+    }
+    decompressed[decompressed_len] = '\0';
+    out_json = String(reinterpret_cast<const char *>(decompressed));
+    reset_batch_rx();
+    return true;
+  }
+
+  return false;
+}
+
 void setup() {
  Serial.begin(115200);
  delay(200);
@@ -48,6 +255,8 @@ void setup() {
  if (g_role == DeviceRole::Sender) {
    power_sender_init();
    meter_init();
+    g_last_sample_ms = millis() - METER_SAMPLE_INTERVAL_MS;
+    g_last_send_ms = millis();
  } else {
    power_receiver_init();
    wifi_manager_init();
@@ -78,7 +287,11 @@ void setup() {
  }
 }

-static void sender_cycle() {
+static void sender_loop() {
+  uint32_t now_ms = millis();
+
+  if (now_ms - g_last_sample_ms >= METER_SAMPLE_INTERVAL_MS) {
+    g_last_sample_ms = now_ms;
    MeterData data = {};
    data.short_id = g_short_id;
    strncpy(data.device_id, g_device_id, sizeof(data.device_id));
@@ -90,44 +303,29 @@ static void sender_cycle() {
    data.ts_utc = now_utc > 0 ? now_utc : millis() / 1000;
    data.valid = meter_ok;

+    push_meter_sample(data);
    display_set_last_meter(data);
    display_set_last_read(meter_ok, data.ts_utc);
-
-  String json;
-  bool json_ok = meterDataToJson(data, json);
-
-  bool tx_ok = false;
-  if (json_ok) {
-    uint8_t compressed[LORA_MAX_PAYLOAD];
-    size_t compressed_len = 0;
-    if (compressBuffer(reinterpret_cast<const uint8_t *>(json.c_str()), json.length(), compressed, sizeof(compressed), compressed_len)) {
-      LoraPacket pkt = {};
-      pkt.protocol_version = PROTOCOL_VERSION;
-      pkt.role = DeviceRole::Sender;
-      pkt.device_id_short = g_short_id;
-      pkt.payload_type = PayloadType::MeterData;
-      pkt.payload_len = compressed_len;
-      memcpy(pkt.payload, compressed, compressed_len);
-      tx_ok = lora_send(pkt);
-    }
  }

-  display_set_last_tx(tx_ok, data.ts_utc);
-  display_tick();
+  if (now_ms - g_last_send_ms >= METER_SEND_INTERVAL_MS) {
+    g_last_send_ms = now_ms;
+    send_meter_batch(last_sample_ts());
+  }

  LoraPacket rx = {};
-  if (lora_receive(rx, 200) && rx.protocol_version == PROTOCOL_VERSION && rx.payload_type == PayloadType::TimeSync) {
+  if (lora_receive(rx, 0) && rx.protocol_version == PROTOCOL_VERSION && rx.payload_type == PayloadType::TimeSync) {
    time_handle_timesync_payload(rx.payload, rx.payload_len);
  }

-  uint32_t start = millis();
-  while (millis() - start < SENDER_OLED_READ_MS) {
  display_tick();
-    delay(50);
+
+  uint32_t next_sample_due = g_last_sample_ms + METER_SAMPLE_INTERVAL_MS;
+  uint32_t next_send_due = g_last_send_ms + METER_SEND_INTERVAL_MS;
+  uint32_t next_due = next_sample_due < next_send_due ? next_sample_due : next_send_due;
+  if (next_due > now_ms) {
+    light_sleep_ms(next_due - now_ms);
  }
-  display_power_down();
-  lora_sleep();
-  go_to_deep_sleep(SENDER_WAKE_INTERVAL_SEC);
 }

 static void receiver_loop() {
@@ -135,7 +333,8 @@ static void receiver_loop() {
    g_last_timesync_ms = millis() - (TIME_SYNC_INTERVAL_SEC * 1000UL - TIME_SYNC_OFFSET_MS);
  }
  LoraPacket pkt = {};
-  if (lora_receive(pkt, 0) && pkt.protocol_version == PROTOCOL_VERSION && pkt.payload_type == PayloadType::MeterData) {
+  if (lora_receive(pkt, 0) && pkt.protocol_version == PROTOCOL_VERSION) {
+    if (pkt.payload_type == PayloadType::MeterData) {
      uint8_t decompressed[256];
      size_t decompressed_len = 0;
      if (decompressBuffer(pkt.payload, pkt.payload_len, decompressed, sizeof(decompressed) - 1, decompressed_len)) {
@@ -157,6 +356,29 @@ static void receiver_loop() {
          }
        }
      }
+    } else if (pkt.payload_type == PayloadType::MeterBatch) {
+      String json;
+      if (process_batch_packet(pkt, json)) {
+        MeterData samples[METER_BATCH_MAX_SAMPLES];
+        size_t count = 0;
+        if (jsonToMeterBatch(json, samples, METER_BATCH_MAX_SAMPLES, count)) {
+          for (uint8_t i = 0; i < NUM_SENDERS; ++i) {
+            if (pkt.device_id_short == EXPECTED_SENDER_IDS[i]) {
+              for (size_t s = 0; s < count; ++s) {
+                samples[s].short_id = pkt.device_id_short;
+                mqtt_publish_state(samples[s]);
+              }
+              if (count > 0) {
+                g_sender_statuses[i].last_data = samples[count - 1];
+                g_sender_statuses[i].last_update_ts_utc = samples[count - 1].ts_utc;
+                g_sender_statuses[i].has_data = true;
+              }
+              break;
+            }
+          }
+        }
+      }
+    }
  }

  if (!g_ap_mode && millis() - g_last_timesync_ms > TIME_SYNC_INTERVAL_SEC * 1000UL) {
@@ -188,7 +410,7 @@ void loop() {
 #endif

  if (g_role == DeviceRole::Sender) {
-    sender_cycle();
+    sender_loop();
  } else {
    receiver_loop();
  }
--- a/src/meter_driver.cpp
+++ b/src/meter_driver.cpp
@@ -1,6 +1,7 @@
 #include "meter_driver.h"
 #include "config.h"
 #include <math.h>
+#include <stdlib.h>
 #include <string.h>

 static constexpr uint32_t METER_READ_TIMEOUT_MS = 2000;
@@ -76,7 +77,7 @@ void meter_init() {
  Serial2.begin(9600, SERIAL_7E1, PIN_METER_RX, -1);
 }

-bool meter_read(MeterData &data) {
+static bool meter_read_sml(MeterData &data) {
  uint8_t buffer[SML_BUFFER_SIZE];
  size_t len = 0;
  bool started = false;
@@ -164,3 +165,182 @@ parse_frame:
  data.valid = ok;
  return ok;
 }
+
+static bool parse_obis_ascii_value(const char *line, const char *obis, float &out_value) {
+  const char *p = strstr(line, obis);
+  if (!p) {
+    return false;
+  }
+  const char *lparen = strchr(p, '(');
+  if (!lparen) {
+    return false;
+  }
+  const char *cur = lparen + 1;
+  char num_buf[24];
+  size_t n = 0;
+  while (*cur && *cur != ')' && *cur != '*') {
+    char c = *cur++;
+    if ((c >= '0' && c <= '9') || c == '-' || c == '+' || c == '.' || c == ',') {
+      if (c == ',') {
+        c = '.';
+      }
+      if (n + 1 < sizeof(num_buf)) {
+        num_buf[n++] = c;
+      }
+    } else if (n == 0) {
+      continue;
+    } else {
+      break;
+    }
+  }
+  if (n == 0) {
+    return false;
+  }
+  num_buf[n] = '\0';
+  out_value = static_cast<float>(atof(num_buf));
+  return true;
+}
+
+static bool parse_obis_ascii_unit_scale(const char *line, const char *obis, float &value) {
+  const char *p = strstr(line, obis);
+  if (!p) {
+    return false;
+  }
+  const char *asterisk = strchr(p, '*');
+  if (!asterisk) {
+    return false;
+  }
+  const char *end = strchr(asterisk, ')');
+  if (!end) {
+    return false;
+  }
+  char unit_buf[8];
+  size_t ulen = 0;
+  for (const char *c = asterisk + 1; c < end && ulen + 1 < sizeof(unit_buf); ++c) {
+    if (*c == ' ') {
+      continue;
+    }
+    unit_buf[ulen++] = *c;
+  }
+  unit_buf[ulen] = '\0';
+  if (ulen == 0) {
+    return false;
+  }
+  if (strcmp(unit_buf, "Wh") == 0) {
+    value *= 0.001f;
+    return true;
+  }
+  return false;
+}
+
+static bool meter_read_ascii(MeterData &data) {
+  const uint32_t start_ms = millis();
+  bool in_telegram = false;
+  bool got_any = false;
+
+  bool energy_ok = false;
+  bool total_p_ok = false;
+  bool p1_ok = false;
+  bool p2_ok = false;
+  bool p3_ok = false;
+  bool v1_ok = false;
+  bool v2_ok = false;
+  bool v3_ok = false;
+
+  char line[128];
+  size_t line_len = 0;
+
+  while (millis() - start_ms < METER_READ_TIMEOUT_MS) {
+    while (Serial2.available()) {
+      char c = static_cast<char>(Serial2.read());
+      if (!in_telegram) {
+        if (c == '/') {
+          in_telegram = true;
+          line_len = 0;
+          line[line_len++] = c;
+        }
+        continue;
+      }
+
+      if (c == '\r') {
+        continue;
+      }
+      if (c == '\n') {
+        line[line_len] = '\0';
+        if (line[0] == '!') {
+          return got_any;
+        }
+
+        float value = NAN;
+        if (parse_obis_ascii_value(line, "1-0:1.8.0", value)) {
+          parse_obis_ascii_unit_scale(line, "1-0:1.8.0", value);
+          data.energy_total_kwh = value;
+          energy_ok = true;
+          got_any = true;
+        }
+        if (parse_obis_ascii_value(line, "1-0:16.7.0", value)) {
+          data.total_power_w = value;
+          total_p_ok = true;
+          got_any = true;
+        }
+        if (parse_obis_ascii_value(line, "1-0:36.7.0", value)) {
+          data.phase_power_w[0] = value;
+          p1_ok = true;
+          got_any = true;
+        }
+        if (parse_obis_ascii_value(line, "1-0:56.7.0", value)) {
+          data.phase_power_w[1] = value;
+          p2_ok = true;
+          got_any = true;
+        }
+        if (parse_obis_ascii_value(line, "1-0:76.7.0", value)) {
+          data.phase_power_w[2] = value;
+          p3_ok = true;
+          got_any = true;
+        }
+        if (parse_obis_ascii_value(line, "1-0:32.7.0", value)) {
+          data.phase_voltage_v[0] = value;
+          v1_ok = true;
+          got_any = true;
+        }
+        if (parse_obis_ascii_value(line, "1-0:52.7.0", value)) {
+          data.phase_voltage_v[1] = value;
+          v2_ok = true;
+          got_any = true;
+        }
+        if (parse_obis_ascii_value(line, "1-0:72.7.0", value)) {
+          data.phase_voltage_v[2] = value;
+          v3_ok = true;
+          got_any = true;
+        }
+
+        line_len = 0;
+        continue;
+      }
+      if (line_len + 1 < sizeof(line)) {
+        line[line_len++] = c;
+      }
+    }
+    delay(5);
+  }
+
+  data.valid = energy_ok || total_p_ok || p1_ok || p2_ok || p3_ok || v1_ok || v2_ok || v3_ok;
+  return data.valid;
+}
+
+bool meter_read(MeterData &data) {
+  data.energy_total_kwh = NAN;
+  data.total_power_w = NAN;
+  data.phase_power_w[0] = NAN;
+  data.phase_power_w[1] = NAN;
+  data.phase_power_w[2] = NAN;
+  data.phase_voltage_v[0] = NAN;
+  data.phase_voltage_v[1] = NAN;
+  data.phase_voltage_v[2] = NAN;
+  data.valid = false;
+
+  if (meter_read_ascii(data)) {
+    return true;
+  }
+  return meter_read_sml(data);
+}
--- a/src/power_manager.cpp
+++ b/src/power_manager.cpp
@@ -47,6 +47,14 @@ uint8_t battery_percent_from_voltage(float voltage_v) {
  return static_cast<uint8_t>(pct + 0.5f);
 }

+void light_sleep_ms(uint32_t ms) {
+  if (ms == 0) {
+    return;
+  }
+  esp_sleep_enable_timer_wakeup(static_cast<uint64_t>(ms) * 1000ULL);
+  esp_light_sleep_start();
+}
+
 void go_to_deep_sleep(uint32_t seconds) {
  esp_sleep_enable_timer_wakeup(static_cast<uint64_t>(seconds) * 1000000ULL);
  esp_deep_sleep_start();