arduino

开关，下拉电阻，板载小灯，按开关灯亮

const int ledPin=13;
const int inputPin=2;
void setup() {
  // put your setup code here, to run once:
  pinMode(ledPin, OUTPUT);
  pinMode(inputPin, INPUT);
  //digitalWrite(inputPin, HIGH);
  Serial.begin(9600);
}

void loop() {
  // put your main code here, to run repeatedly:
  int val=digitalRead(inputPin);
  Serial.println(val);
  if(val==HIGH){
    digitalWrite(ledPin, HIGH);
  }else{
    digitalWrite(ledPin, LOW);
  }

}

 下拉电阻作用，开关不按时，引脚2读的是接地

开关按下，电流从5v，走过开关，走到电阻，走到接地