🛠 Faire clignoter la LED RGB du Nicla Vision

Objectives

Get started with the Arduino Nicla Vision using a first sketch: turn the three onboard color LEDs on and off, and understand why the classic "Blink" example must be adapted for this board.

Hardware

• Arduino Nicla Vision (SKU ABX00051, 22.86 × 22.86 mm)
• Micro-USB data cable (some cables only support charging)
• Arduino IDE with the "Arduino Mbed OS Nicla Boards" core (ArduinoCore-mbed) installed via the Board Manager

Complete code

// Nicla Vision : LEDR=23, LEDG=24 (=LED_BUILTIN), LEDB=25
// > 
const int RGB_PINS[3] = {LEDR, LEDG, LEDB};

void setup {
  for (int p : RGB_PINS) {
    pinMode(p, OUTPUT);
    digitalWrite(p, HIGH);   // LED eteintes
  }
}

void loop {
  digitalWrite(LEDG, LOW);  delay(150);  // vert ON
  digitalWrite(LEDG, HIGH); delay(150);
  digitalWrite(LEDR, LOW);  delay(150);  // rouge ON
  digitalWrite(LEDR, HIGH); delay(150);
  digitalWrite(LEDB, LOW);  delay(400);  // bleu ON
  digitalWrite(LEDB, HIGH); delay(400);
}

Expected verification

The green LED, then the red one, then the blue one light up in turn in the sequence. The board's USB port is a USB CDC (VID 0x2341 / PID 0x025F): if the sketch compiles and uploads, the toolchain is correct. The core runs the sketch on the Cortex-M7 at 480 MHz; the second core (M4) is not needed here.

Common errors

• Including the Nicla_System library: its RGBled.h header contains a #define Mode 1 that collides with the Mode enum in Mbed's InterfaceCAN.h — the sketch does not compile (open bug arduino/ArduinoCore-mbed#615 since January 2023). Hence the direct use of the LEDR/LEDG/LEDB pins above.
• Forgetting DFU mode: the original bootloader is MCUboot; to force reflashing, double-press reset or open the serial port at 1200 baud, then flash via USB DFU.
• Charge-only cable: no COM port appears; try another cable.
• Inverting HIGH/LOW: if the LEDs stay on instead of blinking, the active level is the opposite of the assumption — invert the digitalWrite calls.