#define pinled 4
#define pinbt 3


void setup() {
  // put your setup code here, to run once:
pinMode (pinled, OUTPUT);
pinMode (pinbt, INPUT_PULLUP);
}

void loop() {
  // put your main code here, to run repeatedly:
if (digitalRead(pinbt)==0){
  digitalWrite(pinled, HIGH);
  } else {
    digitalWrite(pinled, LOW);
  }

}