int red= PA0;
int blue= PA1;
int green= PA2;

void setup() {
 
 pinMode(red, OUTPUT);
 pinMode(blue, OUTPUT);
 pinMode(green, OUTPUT);
}

void loop() {
digitalWrite(red, HIGH);
digitalWrite(blue , LOW);
digitalWrite(green , LOW);
delay(500);

digitalWrite(red, LOW);
digitalWrite(blue , HIGH);
digitalWrite(green , LOW);
delay(500);

digitalWrite(red, LOW);
digitalWrite(blue , LOW);
digitalWrite(green , HIGH);
delay(500);
}