#include <Wire.h>

#define NICLA_MASTER_ADDR 0x42
#define LED_PIN 2

#define I2C_SDA 19
#define I2C_SCL 16

volatile uint8_t lastMatch = 0;

void receiveEvent(int howMany) {
    while (Wire.available()) {
        lastMatch = Wire.read();
        if (lastMatch != 0) {
            digitalWrite(LED_PIN, HIGH);
            delay(150);
            digitalWrite(LED_PIN, LOW);
            delay(150);
        }
    }
}

void setup() {
    pinMode(LED_PIN, OUTPUT);
    digitalWrite(LED_PIN, LOW);

    Wire.begin(NICLA_MASTER_ADDR, I2C_SDA, I2C_SCL);
    Wire.onReceive(receiveEvent);
}

void loop() {
    // passiv warten
}