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>

include/config.h

@@ -0,0 +1,62 @@
+#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