const int buttonPin = 6; const int redPin = 3 ; const int yellowPin = 4 ; const int greenPin = 5 ; int buttonState = 0 ; int busyState = 0 ; void setup() { Serial.begin(9600); // initialize LED pins: pinMode(redPin, OUTPUT); pinMode(greenPin, OUTPUT); pinMode(yellowPin, OUTPUT); pinMode(buttonPin, INPUT); } void loop(){ // read the button value: buttonState = digitalRead(buttonPin); if (buttonState == LOW) { busyState += 1 ; if (busyState>3){ busyState = 1 ; } Serial.println(busyState); switch (busyState) { case 0: digitalWrite(redPin, LOW); digitalWrite(yellowPin, LOW); digitalWrite(greenPin, LOW); break; case 1: digitalWrite(redPin, HIGH); digitalWrite(yellowPin, LOW); digitalWrite(greenPin, LOW); Serial.println("in case 1"); break; case 2: digitalWrite(redPin, LOW); digitalWrite(yellowPin, HIGH); digitalWrite(greenPin, LOW); Serial.println("in case 2"); break; case 3: digitalWrite(redPin, LOW); digitalWrite(yellowPin, LOW); digitalWrite(greenPin, HIGH); Serial.println("in case 3"); break; } delay(200); } }