Arduino Program

const int buttonPin = 2;     // the number of the pushbutton pin
const int rled = 13;      // the number of the LED pin
const int gled = 7;
const int bled = 12;
int buttonState = 0;// variable for reading the pushbutton status
volatile int ledstate=0;
void setup() {
   // initialize the LED pin as an output:
   pinMode(gled, OUTPUT);
   pinMode(rled,OUTPUT);
   pinMode(bled,OUTPUT);
   // initialize the pushbutton pin as an input:
   pinMode(buttonPin, INPUT);
  attachInterrupt(digitalPinToInterrupt(buttonPin), pin_ISR, RISING);

}

void pin_ISR() {
  ledstate++;
}



void loop() {  
   // read the state of the pushbutton value:
   if(ledstate==1){
    digitalWrite(rled, HIGH);
   digitalWrite(bled, LOW);
   digitalWrite(gled,LOW);
   }
  else if(ledstate==2){
    digitalWrite(gled, HIGH);
    digitalWrite(rled, LOW);
    digitalWrite(bled, LOW);
   }
  else  if(ledstate==3){
    digitalWrite(bled, HIGH);
    digitalWrite(gled, LOW);
    digitalWrite(rled, LOW);
   }
  else if(ledstate==4){
    digitalWrite(rled, HIGH);
    digitalWrite(gled, HIGH);
    digitalWrite(bled, HIGH);
   }
  else{
    digitalWrite(rled,LOW);
    digitalWrite(gled,LOW);
    digitalWrite(bled,LOW);
  }
  if(ledstate>=5){
    ledstate=0;
  }
  
}