Count Button Presses

Part of the Inputs section of Coddy's Arduino journey. Lesson 5 of 22.

The edge from the last lesson can drive anything that should happen once per press. Here it adds one to a counter, with ++ from Counting Up:

int presses = 0;

void loop() {
  int reading = digitalRead(2);
  if (reading == LOW && lastReading == HIGH) {
    presses++;
    Serial.println(presses);
  }
  lastReading = reading;
}

presses sits above setup(), like lastReading, so it keeps its value between runs of loop().

The print is inside the if, so a number appears only when the count changes: 1, 2, 3. Outside the if it would print the same count thousands of times a second.

Challenge

Easy

The button is on pin 2 (INPUT_PULLUP). Count its presses:

keep the count in presses, declared above setup()
when the button goes down, add one and print the count

Press Run, press the button a few times and watch the Serial monitor, then Check.

Try it yourself

const int buttonPin = 2;

int lastReading = HIGH;

void setup() {
  pinMode(buttonPin, INPUT_PULLUP);
  Serial.begin(9600);
}

void loop() {
  int reading = digitalRead(buttonPin);
  // when the button goes down, count it and print the count
  lastReading = reading;
}

Test yourself

This lesson includes a short quiz. Start the lesson to answer it and track your progress.

All lessons in Inputs

Practice on your own: Arduino playground