Connecting a Push Button to an Arduino Uno with Two Wires

Mar 02, 2015 at 03:04PM

This isn't as complicated as some tutorials make it seem. You don't need a resistor and each push button just needs one wire to an input pin and one wire to ground. Wire up your button to your Uno like this:

In the setup() function of your code set the input pin to INPUT_PULLUP:

void setup() {
    pinMode(8, INPUT_PULLUP);
}

To determine if your button is being pushed you do a standard digitalRead on the pin. The only tricky part with this is that you aren't looking for a HIGH signal like you might assume – your button will give off LOW when it's pressed. You'll also want to add a delay statement to limit the amount of reads per second you perform on the button. This keeps your code from executing over and over when your button is held down. Here's the code:

void loop() {
    if (digitalRead(8) == LOW) {
        //The button is pressed!
 }

    delay(100);
}

Multiple Buttons

It's easy to expand out to more buttons – just make sure they share a common ground. Here's an example with two buttons:

void setup() {
    pinMode(12, INPUT_PULLUP);
    pinMode(11, INPUT_PULLUP);
}

void loop() {
    if (digitalRead(12) == LOW) {
      //Button one is pressed!
 }

    if (digitalRead(11) == LOW) {
      //Button two is pressed!
 }

    delay(100);
}

Bonus Pins

If you're out of digital pins on your Uno, the analog input pins can be used as bonus digital pins – great if you've already used all your digital pins up through something with a lot of wiring like a seven-segment display.