🛠 Capturer une image avec la caméra GC2145 (DCMI)

Objectives

Initialize the embedded 2 Mpx GalaxyCore GC2145 color camera, capture QVGA 320×240 images in RGB565 format via the STM32H747 parallel DCMI bus, and stream them over USB.

Hardware

• Arduino Nicla Vision (integrated GC2145 sensor — not the Himax HM01B0, which is reserved for other boards)
• "Arduino Mbed OS Nicla Boards" core (the Camera library is provided with the core, not as a separate repository)
• PC with a raw RGB565 image viewer (e.g., the official Processing sketch CameraRawBytesVisualizer)
• Key constraint: resolutions above 320×240 require external RAM (SDRAM), which the Nicla Vision does NOT have — stay at QVGA

Complete code

// Adapte de l'exemple officiel CameraCaptureRawBytes (ArduinoCore-mbed)
#include "camera.h"
#include "gc2145.h"

GC2145 galaxyCore;          // capteur couleur 2MP embarque
Camera cam(galaxyCore);     // API Camera commune
#define IMAGE_MODE CAMERA_RGB565

FrameBuffer fb;             // tampon par defaut 320x240x2

void blinkLED(uint32_t count) {
  pinMode(LED_BUILTIN, OUTPUT);
  while (count--) { digitalWrite(LED_BUILTIN, LOW);  delay(50);
                    digitalWrite(LED_BUILTIN, HIGH); delay(50); }
}

void setup {
  // QVGA 30 FPS ; clignotement infini si le capteur ne repond pas
  if (!cam.begin(CAMERA_R320x240, IMAGE_MODE, 30)) blinkLED(0xFFFFFFFF);
  blinkLED(5);              // 5 clignotements = camera OK
}

void loop {
  if (!Serial) { Serial.begin(115200); while (!Serial); }
  if (cam.grabFrame(fb, 3000) == 0)                 // timeout 3 s
    Serial.write(fb.getBuffer, cam.frameSize);  // frame RGB565 brute
  else
    blinkLED(20);                                   // erreur de capture
}

Expected verification

Upon upload, 5 flashes of the green LED confirm the GC2145 initialization. The viewer (Processing, RGB565 320×240 mode) displays a smooth stream. Infinite blinking from setup = the sensor is not responding on the bus (check that the core is up to date).

Common errors

• Aiming for higher than QVGA: Resolutions above 320×240 require SDRAM.h and the external RAM of a Portenta; on the Nicla Vision, the buffer fits exactly in internal RAM — otherwise, you will get allocation errors or corrupted frames.

• Corrupted frames in the viewer: Known bug (arduino/ArduinoCore-mbed#559, series/endianess); check for a high baudrate (921600 or higher) and the byte ordering mode of the viewer.
• Looking for a HM01B0 global shutter: The HM01B0/HM0360 driver in the Camera library does NOT apply to this board; here it is indeed GC2145 galaxyCore.
• Forgetting the timeout: grabFrame(fb) without a delay can block; pass 3000 ms as shown above.
• USB Baudrate: On Mbed, the CDC often ignores the value; keep 115200 on the viewer side and limit the upstream data rate.