🛠 Bouton poussoir et console série

Objectives

Read a push button on a digital pin of the MKR WAN 1310, count the presses, and display them on the serial console via the SAMD21's native USB. Reminders: 8 digital pins at 3.3 V, 8 external interrupts (0, 1, 4, 5, 6, 7, 8, 16/A1, 17/A2), 7 mA max per pin.

Hardware

• 1 MKR WAN 1310 board
• 1 push button
• Wires: button between pin 1 and GND (the pull-up resistor is internal)

Complete code

// Bouton sur broche 1 + console série — MKR WAN 1310
const int BUTTON = 1;   // broche compatible EINT pour un réveil future
const int LED    = 6;   // LED_BUILTIN
unsigned long appuis = 0;
unsigned long dernierAppui = 0;

void setup {
  pinMode(BUTTON, INPUT_PULLUP);
  pinMode(LED, OUTPUT);
  Serial.begin(115200);
  while (!Serial);
  Serial.println("Appuyez sur le bouton (broche 1 -> GND)");
}

void loop {
  if (digitalRead(BUTTON) == LOW) {          // actif bas : tirage interne
    unsigned long maintenant = millis;
    if (maintenant - dernierAppui > 50) {    // anti-rebond logiciel 50 ms
      appuis++;
      dernierAppui = maintenant;
      Serial.print("Appui n°");
      Serial.println(appuis);
      digitalWrite(LED, HIGH);
    } else {
      digitalWrite(LED, LOW);
    }
  }
}

Expected verification

Each press displays "Press n°X" in the serial monitor (115200 baud) and turns on D6. The counter does not increase by several counts with a single press thanks to the debouncing.

Common errors

• Wiring the button to 3.3 V while the code uses INPUT_PULLUP (active low): the signal then remains permanently low.
• Forgetting the debouncing and seeing the counter jump by 3 to 10 with each press.
• Expecting the ON LED to light up when running on battery: it follows the 5 V USB/VIN, not the Li-Po battery charged by the BQ24195L.
• Not selecting the MKR WAN 1310 board in the IDE: the serial port disappears during upload (1200 baud reset), this is normal.