//code for master
#include <Wire.h>
#define SDA_PIN 5
#define SCL_PIN 6
#define SLAVE_ADDR 0x08

void setup() {
  Serial.begin(115200);
  Wire.begin(SDA_PIN, SCL_PIN);

  Serial.println("ESP32 Master Ready");
}

void loop() {
  Serial.println("Sending command: 1");

  Wire.beginTransmission(SLAVE_ADDR);
  Wire.write(1);
  byte error = Wire.endTransmission();

  if (error == 0) {
    Serial.println("Success");
  } else {
    Serial.print("Error: ");
    Serial.println(error);
  }

  delay(2000);
}


// code for SLAVE
#include <Wire.h>
#define LED_PIN PIN_PA7  // PA5 pin where LED is connected
#define I2C_ADDR 0x08    // I2C address for this device

volatile uint8_t command = 0;  // Stores received command (volatile → used in interrupt)


// ── I2C Receive Callback ───────────────────
void receiveEvent(int howMany) {

  if (Wire.available()) {
    command = Wire.read();  // Read incoming command byte
  }
}


void setup() {
  pinMode(LED_PIN, OUTPUT);      // Set LED pin as output
  Wire.begin(I2C_ADDR);          // Initialize as I2C Subordinate
  Wire.onReceive(receiveEvent);  // Register callback when data is received
}


void loop() {
  if (command == 1) {
    // If command is 1 → blink LED

    blinkTwice();  // Call blink function
    command = 0;   // Reset command after execution
  }
}


// ── Blink LED twice ────────────────────────
void blinkTwice() {
  for (int i = 0; i < 2; i++) {

    digitalWrite(LED_PIN, HIGH);  // Turn LED ON
    delay(200);                   // Keep it ON for 200ms
    digitalWrite(LED_PIN, LOW);   // Turn LED OFF
    delay(200);                   // Keep it OFF for 200ms
  }
}