#define pinSwitch 2
#define pinRelay 3
 
void setup() {
  // put your setup code here, to run once:
pinMode(pinSwitch, INPUT_PULLUP);
pinMode(pinRelay, OUTPUT);
}

void loop() {
  // put your main code here, to run repeatedly:
int nilaiSwitch = digitalRead((pinSwitch));

if(nilaiSwitch==0){
  digitalWrite(pinRelay, HIGH);
  } else{
    digitalWrite(pinRelay,LOW);
  }
}