Arduino button LED not working

问题

When I push the button it turns the KY008 off but when I click it again it won't turn it off, but if I jiggle the Laser Diode a little bit the KY008 turns back on.

Code:

int LED = 12;
int BUTTON = 4;

void setup(){
   pinMode(LED,OUTPUT);
   pinMode(BUTTON,INPUT);
}

void loop(){
    if(digitalRead(BUTTON) == HIGH){
        digitalWrite(LED,HIGH);
    }else{ 
    digitalWrite(LED,LOW);
    }
}

回答1:

If you use INPUT you need to have a physical pullup (or pulldown) resistor (typically 10k).

Otherwise use INPUT_PULLUP to use the Arduino internal pullup resistors

pinMode(BUTTON, INPUT_PULLUP);

Make sure that your button closes the circuit to ground when pressed.

Also when reading a button you will have a lot of bouncing. The easiest way to prevent the bouncing is to add a delay between reads.

void loop(){
    if(digitalRead(BUTTON) == HIGH){
        digitalWrite(LED,HIGH);
    }else{ 
        digitalWrite(LED,LOW);
    }
    delay(100);
}

来源：https://stackoverflow.com/questions/48646503/arduino-button-led-not-working