Push button with Arduino Uno R3

Wiring for the Push button on the Arduino Uno R3 (ATmega328P, 5 V logic), chosen with the same pin rules BoardPilot uses: default buses first, and no pins that are used for flash, USB, the debugger or booting.

Wiring

Push button pin	Role	Arduino Uno R3 pin	Notes
1	Output from the part	2 (PD2)	To a GPIO; use INPUT_PULLUP in code
2	Ground	GND

Check before you power it on

The Push button is a 3.3 V part and the Arduino Uno R3 uses 5 V signals. Power it from 3.3 V and put a level shifter on the signal wires, or buy a 5 V version of the module.

Test code (Arduino)

void setup() {
  Serial.begin(115200);
  pinMode(2, INPUT_PULLUP);  // pressed = LOW
}

void loop() {
  Serial.println(digitalRead(2) == LOW ? "pressed" : "released");
  delay(100);
}

Arduino board: arduino:avr:uno.

Questions

Which Arduino Uno R3 pins do I use for the Push button?

1 → 2 (PD2), 2 → GND.

Does the Push button work with the Arduino Uno R3 at 5 V?

The Push button is a 3.3 V part and the Arduino Uno R3 uses 5 V signals. Power it from 3.3 V and put a level shifter on the signal wires, or buy a 5 V version of the module.

BoardPilot checks this wiring in 3D as you build it, and finds crossed or missing wires on the real board.

Download BoardPilot

Full Arduino Uno R3 pinout · Push button: all pins and data

The Push button on other boards

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