ESP32 Lightning Detector: AS3935 Sensor Demo

// ESP32 AS3935 educational lightning sensor demo
// Not a life-safety warning system. Follow official weather alerts.
#include <SPI.h>
#include <Wire.h>
#include <Adafruit_SSD1306.h>
#include <SparkFun_AS3935.h>

const int AS3935_CS = 5;
const int AS3935_IRQ = 4;
const int LED_PIN = 26;

SparkFun_AS3935 lightning(AS3935_CS);
Adafruit_SSD1306 oled(128, 64, &Wire, -1);

volatile bool eventFlag = false;

void IRAM_ATTR onAs3935Event() {
  eventFlag = true;
}

void setup() {
  Serial.begin(115200);
  Wire.begin(21, 22);
  SPI.begin(18, 19, 23, AS3935_CS);
  oled.begin(SSD1306_SWITCHCAPVCC, 0x3C);
  oled.setTextColor(WHITE);
  pinMode(LED_PIN, OUTPUT);
  pinMode(AS3935_IRQ, INPUT);

  if (!lightning.beginSPI(AS3935_CS, 2000000)) {
    Serial.println("AS3935 not found. Check SPI wiring and 3.3 V power.");
    while (true) delay(10);
  }

  lightning.setIndoorOutdoor(INDOOR);
  lightning.maskDisturber(false);
  lightning.setNoiseLevel(2);
  lightning.spikeRejection(2);
  attachInterrupt(digitalPinToInterrupt(AS3935_IRQ), onAs3935Event, RISING);

  Serial.println("AS3935 demo ready. Do not test outdoors during storms.");
}

void loop() {
  if (!eventFlag) return;
  eventFlag = false;
  delay(5);

  int type = lightning.readInterruptReg();
  if (type == NOISE_INT) {
    Serial.println("Noise event. Move the sensor away from electronics or raise noise level.");
  } else if (type == DISTURBER_INT) {
    Serial.println("Disturber event. Electrical interference, not confirmed lightning.");
  } else if (type == LIGHTNING_INT) {
    int distanceKm = lightning.distanceToStorm();
    Serial.print("Lightning-like event. AS3935 distance code: ");
    Serial.print(distanceKm);
    Serial.println(" km. Not a verified strike distance.");

    digitalWrite(LED_PIN, HIGH);
    delay(100);
    digitalWrite(LED_PIN, LOW);

    oled.clearDisplay();
    oled.setTextSize(1);
    oled.setCursor(0, 0);
    oled.println("Lightning-like event");
    oled.print("Distance code: ");
    oled.print(distanceKm);
    oled.println(" km");
    oled.println("Use official alerts");
    oled.display();
  }
}