USB video class(UVC) for Pico

Capture video on your Raspberry Pi Pico with a tinyUSB library.

Hardware

• RP2040 board
• Raspberry Pi Pico
• ov2640 camera module within 24Mhz osc
• ILI9341 2.8 TFT SPI 240x320 V1.2 LCD module

Build

~$ git clone  https://github.com/yjdwbj/rp2040-uvc
~$ cd rp2040-uvc
~$ git submodule update --init
~$ mkdir build
~$ cd build; cmake -DUSE_FREERTOS=1 ../ && make

Tips

• cmake -DUSE_FREERTOS=1 will enable FreeRTOS support which is recommand, otherwise use main loop instead.
• If you set the OV2640 pixel format to RGB565, write the frame buffer directly to LCD and convert rgb565 -> yuv422 to UVC stream.
• If you set the OV2640 pixel format to YUV422, write the frame buffer directly to UVC and convert yuv422 -> rgb565 to LCD. But there is a serious bug here, green/inverted block areas are very frequent.

Demo run

Default Pinout

V42l-ctrl examples

• query the capture formats the video device supports

v4l2-ctl -d 0 --list-formats-ext
ioctl: VIDIOC_ENUM_FMT
        Type: Video Capture

        [0]: 'YUYV' (YUYV 4:2:2)
                Size: Discrete 320x240
                        Interval: Stepwise 0.040s - 1.000s with step 0.040s (1.000-25.000 fps)

• capture raw video stream from by v4l2-ctl.

v4l2-ctl --device /dev/video0
--set-fmt-video=width=320,height=240,pixelformat=YUYV --stream-mmap
--stream-to=frame.raw --stream-count=1

• converted into JPEG format by ffmpeg.

ffmpeg -y -s:v 320x240 -pix_fmt yuyv422 -i frame.raw frame.jpg

FFmpeg examples

• play video from uvc device on linux.

ffplay  -f v4l2 -framerate 25  -video_size 320x240  -i /dev/video0