Button Input with digitalRead

Why it’s here

Read a digital input and use it to control an LED.

How it works

A pull-down sets a known LOW state when the button is released. Pressing the button makes the input HIGH, and the LED mirrors that state. This is an idealized switch; contact bounce is not modeled.

Try it

1. Open this experiment
2. Run the circuit, press the button, then release it. Watch D2 and the LED rather than judging the result from the button animation alone.

Connections

• D2 — Button + 10 kΩ pull-down
• D13 — Resistor → LED
• 5V / GND — Input supply / return

Example sketch

void setup() {
  pinMode(2, INPUT);
  pinMode(13, OUTPUT);
}

void loop() {
  int pressed = digitalRead(2);
  digitalWrite(13, pressed);
}

Check your understanding

What keeps D2 LOW when the button is released?