#include <Wire.h>
#define led PA1
void setup() {
Wire.begin(1);

Wire.onReceive(receiveEvent);
pinMode(led, OUTPUT);
}
void loop() {
delay(100);
}
void receiveEvent(int howMany) {
int x = Wire.read();
if (x == 1)
{
digitalWrite(led, HIGH);
}
if (x == 2)
{
digitalWrite(led, LOW);
}
}