const int SwPin = 17;     
const int ledPin =  16;      
int buttonState = 0;

void setup() {
  Serial.begin(9600);   
  pinMode(SwPin, INPUT); 
  pinMode(ledPin, OUTPUT);
}

void loop() {  
  buttonState = digitalRead(SwPin);
  Serial.println(buttonState); 
  if (buttonState == LOW) {   
    digitalWrite(ledPin, HIGH);
  } else {   
    digitalWrite(ledPin, LOW);
  }
}