سلام بلی بفرمایید:

کد:
int swPin = 8;     // input
int oldval=0;

void setup()                    // run once, when the sketch starts
{
  Serial.begin(9600);
  pinMode(swPin,INPUT);      // sets the digital pin as output
}

void loop()                     // run over and over again
{
val=digitalRead(swPin);
    if(val!=oldval){
        oldval=val;
        Serial.print("val:");
        Serial.print(val);
    }

}