2 · Inputs & sensors
Read a push button
Beginner12 min
Goal
Light the LED only while the button is pressed.
Why it matters
Understanding INPUT_PULLUP avoids the classic “floating input” mistake.
Steps
- 01Add a button on pin 2 and declare pinMode(2, INPUT_PULLUP).
- 02Read it with digitalRead(2).
- 03An if/else drives the LED on pin 13.
This tutorial runs inside the Circuitly simulator: your wiring and your code are checked automatically at every step.
Next tutorials
- Toggle button (debounced)
One press turns on, the next turns off — with no contact bounce.
- Read a potentiometer
Print the analog value of A0 on the serial monitor.
- Convert to volts (map & float)
Turn the ADC's 0–1023 into a 0.00–5.00 V reading.
- Light sensor (LDR)
Turn the LED on automatically when the room gets dark.