🛠 Bouton externe et console série sur le Nicla Vision

Objectives

Read an external push button and display presses in a serial console, to master digital I/O and the USB CDC port of the Nicla Vision.

Hardware

• Arduino Nicla Vision + micro-USB cable
• 1 push button, 1 10 kΩ resistor (the internal pull-up is sufficient in practice)
• Connecting wires; the board exposes 22 digital pins D0–D21
• >

Complete code

// Nicla Vision : 22 broches numeriques D0-D21, logique 3.3 V
const uint8_t BUTTON = D0;
uint32_t appuis = 0;
uint32_t dernierMs = 0;

void setup {
  pinMode(BUTTON, INPUT_PULLUP);   // appui = LOW
  Serial.begin(115200);            // USB CDC (VID 0x2341 / PID 0x025F)
}

void loop {
  static bool etatStable = HIGH;
  bool lecture = digitalRead(BUTTON);
  if (lecture != etatStable && millis - dernierMs > 30) {
    etatStable = lecture;
    dernierMs = millis;
    if (etatStable == LOW) {
      appuis++;
      Serial.print(F("appui n"));
      Serial.println(appuis);
    }
  }
}

Expected verification

Open the serial monitor at 115200 bauds: each press prints "press nN". The button is wired between D0 and GND; without an external pull-up, the internal ~10 kΩ resistor keeps D0 high at rest. The 30 ms debounce scrolling prevents double counting.

Common errors

• Button wired to 3.3 V without a resistor to ground: short circuit when pressed. Always button → pin → GND with pull-up, or button → 3.3 V → pin → resistor → GND.
• Reserved pin: avoid D6/D7 (internal SS), D8–D10 (external SPI bus), D20–D22 (internal SPI1 bus of the LSM6DSOXTR IMU) and D11/D12 (external I²C SDA/SCL). D0 to D5 are safe for this setup.
• Silent console: the Nicla Vision uses USB CDC; on some IDEs you need to check the port wait option or wait for while (!Serial);. Also check the cable (data, not charge-only).
• Random counting without button: pin not configured as INPUT_PULLUP, it floats.