Forest Fire Detector

#include <Arduino.h>
#include <Wire.h>
#include <SPI.h>
#include <SD.h>
#include <LoRa.h>
#include <Adafruit_BME280.h>
#include <Adafruit_ADS1X15.h>
#include <Adafruit_MPU6050.h>
#include <Adafruit_Sensor.h>
#include <RTClib.h>
#include <esp_sleep.h>

constexpr char NODE_ID[] = "forest-01";
constexpr int I2C_SDA_PIN = 8, I2C_SCL_PIN = 9;
constexpr int LORA_NSS_PIN = 10, LORA_MOSI_PIN = 11, LORA_SCK_PIN = 12, LORA_MISO_PIN = 13, LORA_DIO0_PIN = 40;
constexpr int SD_CS_PIN = 41, BUZZER_PIN = 38, WARNING_LED_PIN = 39;
constexpr uint8_t MCP_ADDR = 0x20, WIND_INPUT = 0, RAIN_INPUT = 1;
constexpr long LORA_FREQUENCY_HZ = 433000000L;
constexpr uint64_t NORMAL_SLEEP_US = 300ULL * 1000000ULL, WATCH_SLEEP_US = 120ULL * 1000000ULL, ALERT_SLEEP_US = 60ULL * 1000000ULL;
constexpr float HOT_TEMPERATURE_C = 48.0f, WATCH_TEMPERATURE_C = 39.0f, DRY_HUMIDITY_PCT = 28.0f, IMPACT_G = 2.4f, PM_SMOKE_UG_M3 = 35.0f;
constexpr int16_t FLAME_CHANGE_COUNTS = 900;
constexpr float RAIN_MM_PER_TIP = 0.2794f, WIND_KMH_PER_HZ = 2.4f;

Adafruit_BME280 bme;
Adafruit_ADS1115 ads;
Adafruit_MPU6050 mpu;
RTC_DS3231 rtc;
RTC_DATA_ATTR uint32_t sequenceNumber = 0, rainTipsTotal = 0;
RTC_DATA_ATTR float previousTemperatureC = NAN, temperatureMean = 0.0f, temperatureVariance = 0.0f;
RTC_DATA_ATTR int16_t previousFlame = 0;
RTC_DATA_ATTR uint16_t baselineSamples = 0;
bool bmeReady, adsReady, mpuReady, weatherReady, rtcReady, sdReady, loraReady;

bool mcpWriteRegister(uint8_t reg, uint8_t value) {
  Wire.beginTransmission(MCP_ADDR); Wire.write(reg); Wire.write(value);
  return Wire.endTransmission() == 0;
}
bool mcpReadInput(uint8_t input) {
  Wire.beginTransmission(MCP_ADDR); Wire.write(0x12);
  if (Wire.endTransmission(false) != 0 || Wire.requestFrom((int)MCP_ADDR, 1) != 1) return true;
  return (Wire.read() & (1U << input)) != 0;
}

int16_t readAdsAverage(uint8_t channel) {
  if (!adsReady) return INT16_MIN;
  int32_t sum = 0;
  for (uint8_t i = 0; i < 8; ++i) { sum += ads.readADC_SingleEnded(channel); delay(4); }
  return static_cast<int16_t>(sum / 8);
}
void setAlarm(bool on) { digitalWrite(WARNING_LED_PIN, on); ledcWriteTone(BUZZER_PIN, on ? 2200 : 0); }
void appendLog(const char *line) { if (sdReady) { File f = SD.open("/hazards.csv", FILE_WRITE); if (f) { f.println(line); f.close(); } } }
bool transmit(const char *line, uint8_t tries) {
  if (!loraReady) return false;
  digitalWrite(SD_CS_PIN, HIGH);
  for (uint8_t i = 0; i < tries; ++i) { LoRa.idle(); LoRa.beginPacket(); LoRa.enableCrc(); LoRa.print(line); if (LoRa.endPacket() == 1) { LoRa.sleep(); return true; } delay(300); }
  LoRa.sleep(); return false;
}
void sampleWeather(uint32_t &wind, uint32_t &rain) {
  wind = rain = 0; if (!weatherReady) return;
  bool oldWind = mcpReadInput(WIND_INPUT), oldRain = mcpReadInput(RAIN_INPUT);
  uint32_t lastWind = 0, lastRain = 0, start = millis();
  while (millis() - start < 20000UL) {
    uint32_t now = millis(); bool w = mcpReadInput(WIND_INPUT), r = mcpReadInput(RAIN_INPUT);
    if (oldWind && !w && now - lastWind > 35) { ++wind; lastWind = now; }
    if (oldRain && !r && now - lastRain > 35) { ++rain; lastRain = now; }
    oldWind = w; oldRain = r; delay(5);
  }
}
float zScore(float t) { return baselineSamples >= 12 && temperatureVariance >= 0.04f ? (t - temperatureMean) / sqrtf(temperatureVariance) : 0.0f; }
void updateBaseline(float t, bool safe) {
  if (!safe || isnan(t)) return;
  ++baselineSamples; float a = baselineSamples < 24 ? 1.0f / baselineSamples : 0.04f, d = t - temperatureMean;
  temperatureMean += a * d; temperatureVariance = (1.0f - a) * (temperatureVariance + a * d * d);
}
void sleepFor(uint64_t us) { setAlarm(false); esp_sleep_enable_timer_wakeup(us); delay(20); esp_deep_sleep_start(); }

void setup() {
  Serial.begin(115200); pinMode(WARNING_LED_PIN, OUTPUT); pinMode(SD_CS_PIN, OUTPUT); digitalWrite(SD_CS_PIN, HIGH); ledcAttach(BUZZER_PIN, 2200, 8);
  Wire.begin(I2C_SDA_PIN, I2C_SCL_PIN);
  bmeReady = bme.begin(0x77, &Wire) || bme.begin(0x76, &Wire);
  adsReady = ads.begin(0x48, &Wire); if (adsReady) ads.setGain(GAIN_ONE);
  mpuReady = mpu.begin(0x68, &Wire); if (mpuReady) { mpu.setAccelerometerRange(MPU6050_RANGE_4_G); mpu.setFilterBandwidth(MPU6050_BAND_21_HZ); }
  Wire.beginTransmission(MCP_ADDR); weatherReady = (Wire.endTransmission() == 0);
  if (weatherReady) { weatherReady = mcpWriteRegister(0x00, 0x03) && mcpWriteRegister(0x0C, 0x03); }
  rtcReady = rtc.begin(&Wire); if (rtcReady && rtc.lostPower()) rtc.adjust(DateTime(__DATE__, __TIME__));
  SPI.begin(LORA_SCK_PIN, LORA_MISO_PIN, LORA_MOSI_PIN, LORA_NSS_PIN); sdReady = SD.begin(SD_CS_PIN, SPI);
  LoRa.setPins(LORA_NSS_PIN, -1, LORA_DIO0_PIN); loraReady = LoRa.begin(LORA_FREQUENCY_HZ); if (loraReady) { LoRa.setTxPower(14); LoRa.sleep(); }

  float t = NAN, h = NAN, p = NAN; if (bmeReady) { t = bme.readTemperature(); h = bme.readHumidity(); p = bme.readPressure() / 100.0f; }
  float g = NAN; if (mpuReady) { sensors_event_t a, gyro, imut; mpu.getEvent(&a, &gyro, &imut); g = sqrtf(a.acceleration.x*a.acceleration.x + a.acceleration.y*a.acceleration.y + a.acceleration.z*a.acceleration.z) / 9.80665f; }
  int16_t flame = readAdsAverage(0), soil = readAdsAverage(1), batteryRaw = readAdsAverage(2);
  float batteryV = batteryRaw == INT16_MIN ? NAN : batteryRaw * 0.000250f;
  uint32_t windPulses, rainPulses; sampleWeather(windPulses, rainPulses); rainTipsTotal += rainPulses;
  float windKmh = windPulses * WIND_KMH_PER_HZ / 20.0f, rainMm = rainTipsTotal * RAIN_MM_PER_TIP;
  float rise = !isnan(previousTemperatureC) && !isnan(t) ? t - previousTemperatureC : 0.0f;
  int32_t flameDelta = !isnan(previousTemperatureC) && flame != INT16_MIN ? abs((int32_t)flame - previousFlame) : 0;
  bool hot = !isnan(t) && t >= HOT_TEMPERATURE_C, dryWarm = !isnan(t) && !isnan(h) && t >= WATCH_TEMPERATURE_C && h <= DRY_HUMIDITY_PCT;
  bool rapidHeat = rise >= 3.0f, thermalAnomaly = zScore(t) >= 3.0f, optical = flameDelta >= FLAME_CHANGE_COUNTS, impact = !isnan(g) && g >= IMPACT_G, lowBattery = !isnan(batteryV) && batteryV < 3.35f;
  uint8_t evidence = (hot || dryWarm) + (rapidHeat || thermalAnomaly) + optical;
  bool fire = evidence >= 3, watch = evidence > 0 || impact || windKmh >= 45.0f || lowBattery;
  updateBaseline(t, !fire && !impact); previousTemperatureC = t; if (flame != INT16_MIN) previousFlame = flame; ++sequenceNumber;
  uint32_t epoch = rtcReady ? rtc.now().unixtime() : 0;
  char msg[280]; snprintf(msg, sizeof(msg), "id=%s,seq=%lu,ts=%lu,t=%.1f,h=%.1f,p=%.1f,fl=%d,soil=%d,bat=%.3f,wind=%.1f,rain=%.2f,g=%.2f,z=%.2f,r=%u,ev=%u,fire=%u,impact=%u,lowbat=%u,cam=event_pending,ok=%u%u%u%u", NODE_ID, (unsigned long)sequenceNumber, (unsigned long)epoch, t,h,p,flame,soil,batteryV,windKmh,rainMm,g,zScore(t),fire?3:(watch?1:0),evidence,fire,impact,lowBattery,bmeReady,adsReady,mpuReady,rtcReady);
  appendLog(msg); bool sent = transmit(msg, fire ? 3 : 1); Serial.printf("%s,tx=%u\n", msg, sent);
  if (fire || impact) { uint32_t start = millis(); while (millis() - start < 12000UL) { setAlarm(true); delay(220); setAlarm(false); delay(220); } sleepFor(ALERT_SLEEP_US); }
  sleepFor(watch ? WATCH_SLEEP_US : NORMAL_SLEEP_US);
}
void loop() {}