Initial project: XIAO ESP32S3 + SX1262 LoRa sensor link hytte–hjem

- cabin_node: subscribes to local MQTT (ESPHome sensors), sends temperature, battery voltage/SOC and switch states over LoRa SF12 - cabin_gw: receives LoRa packets, publishes JSON to home MQTT broker - Bidirectional: gateway forwards ON/OFF commands from home HA to node - cabin_node always in RX mode (12V powered) — commands arrive instantly - ESPHome config for ESP32 on teknisk rom: Victron MPPT BLE + JBD BMS BLE + DS18B20 temperatures + GPIO switches for varme/VVB Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
2026-03-10 23:11:35 +01:00
commit a544594769
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+.pio/
+include/secrets.h
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+# hytte_link
+
+LoRa-basert sensorlink mellom hytte og hjemme. Sender temperatur (inne/ute),
+batterispenning og SOC fra 12V-anlegg på hytta til MQTT-broker hjemme (alu).
+
+## Arkitektur
+
+```
+Hytte:
+  DS18B20 (inne/ute) ──┐
+  Victron MPPT (BLE) ──┤
+  JBD BMS (BLE) ────── ESP32 (ESPHome, cabin_tech) ──WiFi──► MQTT (lokal HA)
+                                                               │
+                        XIAO ESP32S3 + Wio-SX1262 ◄──MQTT────┘
+                          (cabin_node)
+                              │ LoRa SF12 868 MHz
+                              ▼ 15–20 km
+Hjemme:               XIAO ESP32S3 + Wio-SX1262
+                          (cabin_gw)
+                              │ MQTT publish
+                              ▼
+                        mosquitto (alu, 192.168.86.31)
+                              │
+                        Home Assistant hjemme
+```
+
+## Bygging (PlatformIO)
+
+```bash
+pio run -e cabin_node              # hytte-node
+pio run -e cabin_gw                # hjemme-gateway
+pio run -e cabin_node -t upload
+pio run -e cabin_gw -t upload
+```
+
+## ESPHome (cabin_tech)
+
+```bash
+esphome run esphome/cabin_tech.yaml
+```
+
+## Secrets
+
+Kopier `include/secrets.example.h` → `include/secrets.h` og fyll inn.
+Kopier `esphome/secrets.yaml.example` → `esphome/secrets.yaml` og fyll inn.
+
+## LoRa-parametere
+
+| Parameter   | Verdi  |
+|-------------|--------|
+| Frekvens    | 868 MHz |
+| SF          | 12     |
+| BW          | 125 kHz |
+| CR          | 4/5    |
+| Sync word   | 0xAB   |
+| Airtime     | ~1.3 s |
+
+## Pakkeformat (CabinPacket, 12 bytes)
+
+| Felt         | Type    | Enhet     |
+|--------------|---------|-----------|
+| magic        | uint8   | 0xCA      |
+| seq          | uint8   | rullende  |
+| temp_in_x10  | int16   | °C × 10   |
+| temp_out_x10 | int16   | °C × 10   |
+| batt_mv      | uint16  | mV        |
+| batt_pct     | uint8   | 0–100     |
+| sig          | uint32  | HMAC-SHA256 (trunkert) |
+
+## Pinner (Wio-SX1262 på XIAO ESP32S3)
+
+Verifiser mot Seeed-skjema før flashing:
+- NSS: GPIO44 (D7)
+- RST: GPIO43 (D6)
+- DIO1: GPIO2 (D1)
+- BUSY: GPIO1 (D0)
+
+## MQTT-topics
+
+| Topic                  | Retning              |
+|------------------------|----------------------|
+| hytte/sensor/temp_inne | ESPHome → cabin_node |
+| hytte/sensor/temp_ute  | ESPHome → cabin_node |
+| hytte/sensor/batt_mv   | ESPHome → cabin_node |
+| hytte/sensor/batt_pct  | ESPHome → cabin_node |
+| hytte/lora/status      | cabin_gw → alu       |
@@ -0,0 +1,169 @@
+substitutions:
+  device_name: cabin-tech
+  friendly_name: "Hytte teknisk"
+
+esphome:
+  name: ${device_name}
+  friendly_name: ${friendly_name}
+
+esp32:
+  board: esp32dev
+  framework:
+    type: arduino
+
+logger:
+api:
+  encryption:
+    key: !secret api_key
+
+ota:
+  - platform: esphome
+    password: !secret ota_password
+
+wifi:
+  ssid: !secret wifi_ssid
+  password: !secret wifi_password
+
+mqtt:
+  broker: !secret mqtt_broker
+  port: 1883
+  username: !secret mqtt_username
+  password: !secret mqtt_password
+  topic_prefix: hytte
+
+# ── BLE ──────────────────────────────────────────────────────────────────────
+
+esp32_ble_tracker:
+  scan_parameters:
+    active: false  # passive scanning — don't connect, just listen
+
+# Victron MPPT (SmartSolar) — reads BLE advertisements
+# Get the encryption key from Victron Connect app:
+#   Settings → Product info → Encryption key
+victron_ble:
+  - id: victron_mppt
+    mac_address: !secret victron_mac
+    bindkey: !secret victron_bindkey
+
+sensor:
+  - platform: victron_ble
+    victron_ble_id: victron_mppt
+    battery_voltage:
+      name: "Batteri spenning"
+      id: batt_voltage
+      on_value:
+        then:
+          - mqtt.publish:
+              topic: hytte/sensor/batt_mv
+              payload: !lambda 'return to_string((int)(x * 1000));'
+    battery_current:
+      name: "Batteri strøm"
+    pv_power:
+      name: "Solcelle effekt"
+    load_power:
+      name: "Last effekt"
+    charging_mode:
+      name: "Lademodus"
+
+# JBD/JBD BMS — active BLE client connection
+# External component: https://github.com/syssi/esphome-jbd-bms
+external_components:
+  - source: github://syssi/esphome-jbd-bms@main
+    refresh: 0d
+
+ble_client:
+  - mac_address: !secret jbd_mac
+    id: jbd_ble_client
+
+jbd_bms:
+  - ble_client_id: jbd_ble_client
+    id: jbd
+    update_interval: 60s
+
+sensor:
+  - platform: jbd_bms
+    jbd_bms_id: jbd
+    state_of_charge:
+      name: "Batteri SOC"
+      id: batt_soc
+      on_value:
+        then:
+          - mqtt.publish:
+              topic: hytte/sensor/batt_pct
+              payload: !lambda 'return to_string((int)x);'
+    total_voltage:
+      name: "Total spenning"
+    current:
+      name: "Strøm"
+    power:
+      name: "Effekt"
+    temperature_1:
+      name: "BMS temperatur"
+
+# ── Temperatur ────────────────────────────────────────────────────────────────
+# DS18B20 one-wire — juster pin etter installasjon
+one_wire:
+  - platform: gpio
+    pin: GPIO4
+
+sensor:
+  - platform: dallas_temp
+    name: "Inne temperatur"
+    id: temp_in
+    address: !secret ds18b20_indoor_addr
+    update_interval: 60s
+    on_value:
+      then:
+        - mqtt.publish:
+            topic: hytte/sensor/temp_inne
+            payload: !lambda 'return to_string(x);'
+
+  - platform: dallas_temp
+    name: "Ute temperatur"
+    id: temp_out
+    address: !secret ds18b20_outdoor_addr
+    update_interval: 60s
+    on_value:
+      then:
+        - mqtt.publish:
+            topic: hytte/sensor/temp_ute
+            payload: !lambda 'return to_string(x);'
+
+# ── Bryterkanaler (styres via LoRa-kommandoer) ───────────────────────────────
+
+switch:
+  - platform: gpio
+    name: "Varme"
+    id: switch_varme
+    pin: GPIO16          # juster pin etter installasjon
+    restore_mode: RESTORE_DEFAULT_OFF
+
+  - platform: gpio
+    name: "Varmtvannsbereder"
+    id: switch_vvb
+    pin: GPIO17          # juster pin etter installasjon
+    restore_mode: RESTORE_DEFAULT_OFF
+
+# Lytter på kommandoer fra cabin_node (publisert til lokal MQTT)
+# HA hjemme → MQTT på alu → LoRa → cabin_node → lokal MQTT → her
+mqtt:
+  on_message:
+    - topic: hytte/cmd/varme
+      then:
+        - if:
+            condition:
+              lambda: 'return x == "ON";'
+            then:
+              - switch.turn_on: switch_varme
+            else:
+              - switch.turn_off: switch_varme
+
+    - topic: hytte/cmd/vvb
+      then:
+        - if:
+            condition:
+              lambda: 'return x == "ON";'
+            then:
+              - switch.turn_on: switch_vvb
+            else:
+              - switch.turn_off: switch_vvb
@@ -0,0 +1,15 @@
+wifi_ssid: "din-wifi-ssid"
+wifi_password: "din-wifi-passord"
+mqtt_broker: "192.168.x.x"   # lokal IP til HA/Mosquitto på hytta
+mqtt_username: "mqtt"
+mqtt_password: "ditt-mqtt-passord"
+api_key: ""                   # generer i ESPHome UI
+ota_password: "ota-passord"
+
+victron_mac: "AA:BB:CC:DD:EE:FF"   # finn i Victron Connect → enhet
+victron_bindkey: "aabbccddeeff..."  # Settings → Product info → Encryption key
+
+jbd_mac: "AA:BB:CC:DD:EE:FF"       # finn med BLE-scanner (nRF Connect e.l.)
+
+ds18b20_indoor_addr: "0xAABBCCDDEEFF0028"   # finn med dallas_temp i ESPHome
+ds18b20_outdoor_addr: "0xAABBCCDDEEFF0128"
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+#pragma once
+
+// LoRa radio parameters — must match exactly on node and gateway
+#define LORA_FREQ      868.0   // MHz
+#define LORA_SF        12
+#define LORA_BW        125.0   // kHz
+#define LORA_CR        5
+#define LORA_SYNC_WORD 0xAB    // distinct from ice-track (0x34)
+#define LORA_POWER     22      // dBm (SX1262 max)
+
+// Wio-SX1262 pins for XIAO ESP32S3
+// Verify against https://wiki.seeedstudio.com/wio_sx1262_with_xiao_esp32s3
+#define LORA_NSS       44   // D7
+#define LORA_RST       43   // D6
+#define LORA_DIO1       2   // D1
+#define LORA_BUSY       1   // D0
+
+// Send interval (node) — 30 min fills one packet; adjust 1–4x/hour
+#define SEND_INTERVAL_MS (30UL * 60UL * 1000UL)
+
+// MQTT broker (home, shared with mitt_lora)
+#define MQTT_HOST "192.168.86.31"
+#define MQTT_PORT 1883
+#define MQTT_USER "mqtt"
+#ifndef MQTT_PASS
+#define MQTT_PASS ""
+#endif
+
+// MQTT topics (cabin ESPHome → node subscribes to these)
+#define TOPIC_TEMP_IN   "hytte/sensor/temp_inne"
+#define TOPIC_TEMP_OUT  "hytte/sensor/temp_ute"
+#define TOPIC_BATT_MV   "hytte/sensor/batt_mv"
+#define TOPIC_BATT_PCT  "hytte/sensor/batt_pct"
+
+// MQTT topic gateway publishes received packets to (home broker)
+#define TOPIC_GW_STATUS "hytte/lora/status"
+
+// Command topics (home HA publishes → cabin_gw → LoRa → cabin_node → ESPHome)
+// Payload: "ON" or "OFF"
+#define TOPIC_CMD_VARME  "hytte/cmd/varme"
+#define TOPIC_CMD_VVB    "hytte/cmd/vvb"
+
+// ESPHome publishes switch states here (cabin_node subscribes)
+#define TOPIC_STATE_VARME "hytte/switch/varme/state"
+#define TOPIC_STATE_VVB   "hytte/switch/vvb/state"
+
+// WiFi credentials
+#ifndef WIFI_SSID
+#define WIFI_SSID "your-ssid"
+#endif
+#ifndef WIFI_PASS
+#define WIFI_PASS "your-pass"
+#endif
+
+// HMAC key — 32+ chars, keep secret
+#ifndef HMAC_KEY
+#define HMAC_KEY "hytte-link-hmac-key-replace-me"
+#endif
+
+#if __has_include("secrets.h")
+#include "secrets.h"
+#endif
@@ -0,0 +1,20 @@
+#pragma once
+#include <stdint.h>
+#include <stddef.h>
+#include <string.h>
+#include "mbedtls/md.h"
+#include "config.h"
+
+// Returns a 4-byte truncated HMAC-SHA256 over `data` of `len` bytes.
+inline uint32_t hmac_sig(const uint8_t *data, size_t len)
+{
+  static const char *key = HMAC_KEY;
+  uint8_t out[32];
+  mbedtls_md_hmac(
+    mbedtls_md_info_from_type(MBEDTLS_MD_SHA256),
+    reinterpret_cast<const uint8_t *>(key), strlen(key),
+    data, len, out);
+  uint32_t sig;
+  memcpy(&sig, out, 4);
+  return sig;
+}
@@ -0,0 +1,36 @@
+#pragma once
+#include <stdint.h>
+
+#define CABIN_PACKET_MAGIC 0xCA
+#define CABIN_CMD_MAGIC    0xCB
+
+// Command IDs
+#define CMD_VARME   0x01
+#define CMD_VVB     0x02   // varmtvannsbereder
+
+// Wire format: 13 bytes total
+// At SF12 BW125: ~1.3s airtime
+// flags bits: 0=varme, 1=vvb (1=on, 0=off)
+#define CABIN_FLAG_VARME  (1 << 0)
+#define CABIN_FLAG_VVB    (1 << 1)
+
+struct __attribute__((packed)) CabinPacket {
+  uint8_t  magic;         // = CABIN_PACKET_MAGIC
+  uint8_t  seq;           // rolling counter
+  int16_t  temp_in_x10;   // indoor temp * 10  (213 = 21.3 °C), INT16_MIN = no data
+  int16_t  temp_out_x10;  // outdoor temp * 10, INT16_MIN = no data
+  uint16_t batt_mv;       // battery voltage mV (12V system: ~10000–14400)
+  uint8_t  batt_pct;      // SOC 0–100, 0xFF = no data
+  uint8_t  flags;         // switch states: bit0=varme, bit1=vvb
+  uint32_t sig;           // truncated HMAC-SHA256
+};
+
+// Command packet: home → gateway → node → ESPHome switch
+// 8 bytes total
+struct __attribute__((packed)) CabinCmdPacket {
+  uint8_t  magic;   // = CABIN_CMD_MAGIC
+  uint8_t  seq;
+  uint8_t  cmd_id;  // CMD_VARME, CMD_VVB, ...
+  uint8_t  value;   // 0 = off, 1 = on
+  uint32_t sig;
+};
@@ -0,0 +1,7 @@
+#pragma once
+
+// Copy to secrets.h and fill in before building
+#define WIFI_SSID  "your-wifi-ssid"
+#define WIFI_PASS  "your-wifi-password"
+#define MQTT_PASS  "your-mqtt-password"
+#define HMAC_KEY   "your-secret-hmac-key-at-least-32-chars"
@@ -0,0 +1,26 @@
+[platformio]
+default_envs = cabin_node
+
+[env:cabin_node]
+platform = espressif32
+board = seeed_xiao_esp32s3
+framework = arduino
+build_src_filter = +<cabin_node/> -<cabin_gw/>
+build_flags = -I include
+monitor_speed = 115200
+lib_deps =
+  jgromes/RadioLib@^7.1.2
+  knolleary/PubSubClient@^2.8
+  bblanchon/ArduinoJson@^7.0.4
+
+[env:cabin_gw]
+platform = espressif32
+board = seeed_xiao_esp32s3
+framework = arduino
+build_src_filter = +<cabin_gw/> -<cabin_node/>
+build_flags = -I include
+monitor_speed = 115200
+lib_deps =
+  jgromes/RadioLib@^7.1.2
+  knolleary/PubSubClient@^2.8
+  bblanchon/ArduinoJson@^7.0.4
@@ -0,0 +1,158 @@
+#include <Arduino.h>
+#include <WiFi.h>
+#include <PubSubClient.h>
+#include <RadioLib.h>
+#include <ArduinoJson.h>
+
+#include "config.h"
+#include "packets.h"
+#include "crypto.h"
+
+WiFiClient   wifi_client;
+PubSubClient mqtt(wifi_client);
+SX1262 radio = new Module(LORA_NSS, LORA_DIO1, LORA_RST, LORA_BUSY);
+
+// Pending command — last-write-wins; sent on next data packet received from node
+struct PendingCmd {
+  bool    valid  = false;
+  uint8_t cmd_id = 0;
+  uint8_t value  = 0;
+};
+static PendingCmd pending;
+static uint8_t cmd_seq = 0;
+
+static void on_mqtt(const char *topic, byte *payload, unsigned int len)
+{
+  char buf[8];
+  if (len >= sizeof(buf)) return;
+  memcpy(buf, payload, len);
+  buf[len] = '\0';
+  bool on = (strcasecmp(buf, "ON") == 0 || strcmp(buf, "1") == 0);
+
+  if      (strcmp(topic, TOPIC_CMD_VARME) == 0) { pending = {true, CMD_VARME, (uint8_t)(on ? 1 : 0)}; }
+  else if (strcmp(topic, TOPIC_CMD_VVB)   == 0) { pending = {true, CMD_VVB,   (uint8_t)(on ? 1 : 0)}; }
+
+  Serial.printf("[cmd] queued cmd_id=%u value=%u\n", pending.cmd_id, pending.value);
+}
+
+static void mqtt_connect()
+{
+  while (!mqtt.connected()) {
+    Serial.println("[mqtt] connecting...");
+    if (mqtt.connect("hytte-lora-gw", MQTT_USER, MQTT_PASS)) {
+      mqtt.subscribe(TOPIC_CMD_VARME);
+      mqtt.subscribe(TOPIC_CMD_VVB);
+      Serial.println("[mqtt] connected");
+    } else {
+      Serial.printf("[mqtt] failed rc=%d, retry in 5s\n", mqtt.state());
+      delay(5000);
+    }
+  }
+}
+
+static void send_pending_cmd()
+{
+  if (!pending.valid) return;
+
+  CabinCmdPacket pkt{};
+  pkt.magic  = CABIN_CMD_MAGIC;
+  pkt.seq    = cmd_seq++;
+  pkt.cmd_id = pending.cmd_id;
+  pkt.value  = pending.value;
+  pkt.sig    = hmac_sig(reinterpret_cast<const uint8_t *>(&pkt), sizeof(pkt) - sizeof(pkt.sig));
+
+  int state = radio.transmit(reinterpret_cast<uint8_t *>(&pkt), sizeof(pkt));
+  if (state == RADIOLIB_ERR_NONE) {
+    Serial.printf("[lora] cmd sent cmd_id=%u value=%u\n", pkt.cmd_id, pkt.value);
+    pending.valid = false;
+  } else {
+    Serial.printf("[lora] cmd tx error %d\n", state);
+  }
+
+  // back to receive mode
+  radio.startReceive();
+}
+
+static void handle_data_packet(uint8_t *buf, size_t len)
+{
+  if (len != sizeof(CabinPacket)) return;
+
+  CabinPacket pkt;
+  memcpy(&pkt, buf, sizeof(pkt));
+
+  if (pkt.magic != CABIN_PACKET_MAGIC) return;
+
+  uint32_t expected = hmac_sig(reinterpret_cast<const uint8_t *>(&pkt), sizeof(pkt) - sizeof(pkt.sig));
+  if (pkt.sig != expected) {
+    Serial.println("[lora] bad signature");
+    return;
+  }
+
+  float rssi = radio.getRSSI();
+  float snr  = radio.getSNR();
+
+  Serial.printf("[lora] rx seq=%u in=%.1f out=%.1f batt=%umV %u%% flags=0x%02X rssi=%.0f snr=%.1f\n",
+    pkt.seq,
+    pkt.temp_in_x10  != INT16_MIN ? pkt.temp_in_x10  / 10.0f : NAN,
+    pkt.temp_out_x10 != INT16_MIN ? pkt.temp_out_x10 / 10.0f : NAN,
+    pkt.batt_mv, pkt.batt_pct, pkt.flags, rssi, snr);
+
+  JsonDocument doc;
+  doc["seq"]      = pkt.seq;
+  doc["rssi"]     = (int)rssi;
+  doc["snr"]      = snr;
+  doc["batt_mv"]  = pkt.batt_mv;
+  doc["batt_pct"] = pkt.batt_pct != 0xFF ? (int)pkt.batt_pct : -1;
+  doc["varme"]    = (pkt.flags & CABIN_FLAG_VARME) ? true : false;
+  doc["vvb"]      = (pkt.flags & CABIN_FLAG_VVB)   ? true : false;
+  if (pkt.temp_in_x10  != INT16_MIN) doc["temp_in"]  = pkt.temp_in_x10  / 10.0f;
+  if (pkt.temp_out_x10 != INT16_MIN) doc["temp_out"] = pkt.temp_out_x10 / 10.0f;
+
+  char json[256];
+  serializeJson(doc, json);
+  mqtt.publish(TOPIC_GW_STATUS, json, true);
+
+  // Send any queued command while node is listening
+  send_pending_cmd();
+}
+
+void setup()
+{
+  Serial.begin(115200);
+  delay(100);
+  Serial.println("[gw] boot");
+
+  if (radio.begin(LORA_FREQ) != RADIOLIB_ERR_NONE) {
+    Serial.println("[lora] init failed — halting");
+    while (true) delay(1000);
+  }
+  radio.setSpreadingFactor(LORA_SF);
+  radio.setBandwidth(LORA_BW);
+  radio.setCodingRate(LORA_CR);
+  radio.setSyncWord(LORA_SYNC_WORD);
+  radio.startReceive();
+  Serial.println("[lora] listening sf=12 bw=125 freq=868");
+
+  WiFi.begin(WIFI_SSID, WIFI_PASS);
+  Serial.print("[wifi] connecting");
+  while (WiFi.status() != WL_CONNECTED) { delay(500); Serial.print("."); }
+  Serial.printf("\n[wifi] connected ip=%s\n", WiFi.localIP().toString().c_str());
+
+  mqtt.setServer(MQTT_HOST, MQTT_PORT);
+  mqtt.setCallback(on_mqtt);
+  mqtt_connect();
+
+  Serial.println("[gw] setup done");
+}
+
+void loop()
+{
+  if (!mqtt.connected()) mqtt_connect();
+  mqtt.loop();
+
+  if (radio.available()) {
+    uint8_t buf[sizeof(CabinPacket)];
+    radio.readData(buf, sizeof(buf));
+    handle_data_packet(buf, radio.getPacketLength());
+  }
+}
@@ -0,0 +1,175 @@
+#include <Arduino.h>
+#include <WiFi.h>
+#include <PubSubClient.h>
+#include <RadioLib.h>
+
+#include "config.h"
+#include "packets.h"
+#include "crypto.h"
+
+// Cached sensor values from local MQTT (ESPHome/HA)
+static int16_t  g_temp_in_x10  = INT16_MIN;
+static int16_t  g_temp_out_x10 = INT16_MIN;
+static uint16_t g_batt_mv      = 0;
+static uint8_t  g_batt_pct     = 0xFF;
+static uint8_t  g_flags        = 0;   // switch states
+static uint8_t  g_seq          = 0;
+static uint32_t g_last_send_ms = 0;
+
+WiFiClient   wifi_client;
+PubSubClient mqtt(wifi_client);
+SX1262 radio = new Module(LORA_NSS, LORA_DIO1, LORA_RST, LORA_BUSY);
+
+static void on_mqtt(const char *topic, byte *payload, unsigned int len)
+{
+  char buf[32];
+  if (len >= sizeof(buf)) return;
+  memcpy(buf, payload, len);
+  buf[len] = '\0';
+
+  // Sensor values
+  if (strcmp(topic, TOPIC_TEMP_IN) == 0) {
+    g_temp_in_x10 = (int16_t)(atof(buf) * 10.0f);
+  } else if (strcmp(topic, TOPIC_TEMP_OUT) == 0) {
+    g_temp_out_x10 = (int16_t)(atof(buf) * 10.0f);
+  } else if (strcmp(topic, TOPIC_BATT_MV) == 0) {
+    g_batt_mv = (uint16_t)atof(buf);
+  } else if (strcmp(topic, TOPIC_BATT_PCT) == 0) {
+    g_batt_pct = (uint8_t)atof(buf);
+  // Switch states from ESPHome
+  } else if (strcmp(topic, TOPIC_STATE_VARME) == 0) {
+    if (strcasecmp(buf, "ON") == 0) g_flags |=  CABIN_FLAG_VARME;
+    else                            g_flags &= ~CABIN_FLAG_VARME;
+  } else if (strcmp(topic, TOPIC_STATE_VVB) == 0) {
+    if (strcasecmp(buf, "ON") == 0) g_flags |=  CABIN_FLAG_VVB;
+    else                            g_flags &= ~CABIN_FLAG_VVB;
+  }
+}
+
+static void mqtt_connect()
+{
+  while (!mqtt.connected()) {
+    Serial.println("[mqtt] connecting...");
+    if (mqtt.connect("hytte-lora-node", MQTT_USER, MQTT_PASS)) {
+      mqtt.subscribe(TOPIC_TEMP_IN);
+      mqtt.subscribe(TOPIC_TEMP_OUT);
+      mqtt.subscribe(TOPIC_BATT_MV);
+      mqtt.subscribe(TOPIC_BATT_PCT);
+      mqtt.subscribe(TOPIC_STATE_VARME);
+      mqtt.subscribe(TOPIC_STATE_VVB);
+      Serial.println("[mqtt] connected");
+    } else {
+      Serial.printf("[mqtt] failed rc=%d, retry in 5s\n", mqtt.state());
+      delay(5000);
+    }
+  }
+}
+
+static void handle_cmd(const uint8_t *buf, size_t len)
+{
+  if (len != sizeof(CabinCmdPacket)) return;
+
+  CabinCmdPacket pkt;
+  memcpy(&pkt, buf, sizeof(pkt));
+
+  if (pkt.magic != CABIN_CMD_MAGIC) return;
+
+  uint32_t expected = hmac_sig(reinterpret_cast<const uint8_t *>(&pkt), sizeof(pkt) - sizeof(pkt.sig));
+  if (pkt.sig != expected) {
+    Serial.println("[cmd] bad signature");
+    return;
+  }
+
+  const char *value = pkt.value ? "ON" : "OFF";
+  const char *topic = nullptr;
+  if      (pkt.cmd_id == CMD_VARME) topic = TOPIC_CMD_VARME;
+  else if (pkt.cmd_id == CMD_VVB)   topic = TOPIC_CMD_VVB;
+
+  if (topic) {
+    mqtt.publish(topic, value, true);
+    Serial.printf("[cmd] rx cmd_id=%u → %s = %s\n", pkt.cmd_id, topic, value);
+  } else {
+    Serial.printf("[cmd] unknown cmd_id=%u\n", pkt.cmd_id);
+  }
+}
+
+static void send_lora()
+{
+  if (g_temp_in_x10 == INT16_MIN) {
+    Serial.println("[lora] skip — no sensor data yet");
+    return;
+  }
+
+  CabinPacket pkt{};
+  pkt.magic        = CABIN_PACKET_MAGIC;
+  pkt.seq          = g_seq++;
+  pkt.temp_in_x10  = g_temp_in_x10;
+  pkt.temp_out_x10 = g_temp_out_x10;
+  pkt.batt_mv      = g_batt_mv;
+  pkt.batt_pct     = g_batt_pct;
+  pkt.flags        = g_flags;
+  pkt.sig          = hmac_sig(reinterpret_cast<const uint8_t *>(&pkt), sizeof(pkt) - sizeof(pkt.sig));
+
+  // Pause RX, transmit, resume RX
+  radio.standby();
+  int state = radio.transmit(reinterpret_cast<uint8_t *>(&pkt), sizeof(pkt));
+  radio.startReceive();
+
+  if (state == RADIOLIB_ERR_NONE) {
+    Serial.printf("[lora] sent seq=%u in=%.1f out=%.1f batt=%umV %u%% flags=0x%02X\n",
+      pkt.seq, pkt.temp_in_x10 / 10.0f, pkt.temp_out_x10 / 10.0f,
+      pkt.batt_mv, pkt.batt_pct, pkt.flags);
+  } else {
+    Serial.printf("[lora] tx error %d\n", state);
+  }
+}
+
+void setup()
+{
+  Serial.begin(115200);
+  delay(100);
+  Serial.println("[node] boot");
+
+  if (radio.begin(LORA_FREQ) != RADIOLIB_ERR_NONE) {
+    Serial.println("[lora] init failed — halting");
+    while (true) delay(1000);
+  }
+  radio.setSpreadingFactor(LORA_SF);
+  radio.setBandwidth(LORA_BW);
+  radio.setCodingRate(LORA_CR);
+  radio.setSyncWord(LORA_SYNC_WORD);
+  radio.setOutputPower(LORA_POWER);
+  radio.startReceive();   // always listening — 12V powered
+  Serial.println("[lora] ready + listening sf=12 bw=125 freq=868");
+
+  WiFi.begin(WIFI_SSID, WIFI_PASS);
+  Serial.print("[wifi] connecting");
+  while (WiFi.status() != WL_CONNECTED) { delay(500); Serial.print("."); }
+  Serial.printf("\n[wifi] connected ip=%s\n", WiFi.localIP().toString().c_str());
+
+  mqtt.setServer(MQTT_HOST, MQTT_PORT);
+  mqtt.setCallback(on_mqtt);
+  mqtt_connect();
+
+  g_last_send_ms = millis() - SEND_INTERVAL_MS;
+  Serial.println("[node] setup done");
+}
+
+void loop()
+{
+  if (!mqtt.connected()) mqtt_connect();
+  mqtt.loop();
+
+  // Handle incoming commands (radio always in RX)
+  if (radio.available()) {
+    uint8_t buf[sizeof(CabinCmdPacket)];
+    radio.readData(buf, sizeof(buf));
+    handle_cmd(buf, radio.getPacketLength());
+    radio.startReceive();
+  }
+
+  if (millis() - g_last_send_ms >= SEND_INTERVAL_MS) {
+    send_lora();
+    g_last_send_ms = millis();
+  }
+}