🛠 Lire un bouton avec résistance de pull-up interne

Objectives

Learn how to read a digital input on the Nano Every using a push-button, utilizing the internal pull-up resistor (INPUT_PULLUP) instead of an external resistor. The board features 22 digital I/O pins (0 to 21) operating at 5 V logic.

Hardware

• 1 × Arduino Nano Every
• 1 × push-button
• 1 × jumper wire (pin 2 → button, button → GND)
• Micro-USB cable

Complete Code

// Bouton sur broche 2, logique inversée grâce au pull-up interne
const uint8_t BTN = 2;
bool etatPrecedent = HIGH;

void setup {
  pinMode(LED_BUILTIN, OUTPUT);   // broche 13
  pinMode(BTN, INPUT_PULLUP);     // pull-up interne : HIGH au repos
  Serial.begin(9600);
}

void loop {
  bool etat = digitalRead(BTN);   // LOW = pressé
  if (etat != etatPrecedent) {
    delay(30);                    // anti-rebond logiciel grossier
    etat = digitalRead(BTN);
    Serial.println(etat == LOW ? "Bouton presse" : "Bouton lache");
    etatPrecedent = etat;
  }
  digitalWrite(LED_BUILTIN, etat == LOW ? HIGH : LOW);
}

Expected Verification

Connect the button between pin 2 and GND: at rest, digitalRead returns HIGH (internal pull-up) and LED 13 is off; when pressed, the reading changes to LOW, the LED turns on, and the serial monitor (9600 baud) displays the event. No external resistor is required.

Common Errors

• Wiring the button between the pin and 5 V: with INPUT_PULLUP, the logic is inverted and you short-circuit the pull-up; keep the connection pin → GND.
• Forgetting INPUT_PULLUP: the pin floats, causing readings to change randomly.
• Confusing it with the classic Nano: the pinout is identical, but the Every uses an ATmega4809 — make sure to select the correct board in the IDE.
• Raw mechanical bouncing: without debouncing, a single press generates multiple lines; the delay(30) in this tutorial is a minimal educational approach, prefer millis for real projects.
• Note: the PWM pins on this board are only 3, 5, 6, 9, and 10 — pin 2 is a simple digital I/O, which is sufficient here.