Digital Input Pullup 14

Read buttons, limit switches, and contact sensors with stable internal pullups.

/*
  Roboda verified Arduino sample 0327
  Feature: Digital Input Pullup
  Generated for online build, classroom practice, and hardware upload testing.
*/

const byte buttonPin = 4;
const byte outputPin = 13;

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

void loop() {
  bool pressed = digitalRead(buttonPin) == LOW;
  digitalWrite(outputPin, pressed ? HIGH : LOW);
  Serial.println(pressed ? "pressed" : "released");
  delay(115);
}

How it works

Read a button or limit switch reliably using the internal pullup resistor.

1. Wire one side of the switch to the input pin and the other side to GND.
2. Enable INPUT_PULLUP so no external resistor is required.
3. Treat LOW as pressed and HIGH as released.
4. Mirror the state to D13 and Serial Monitor.

Connections