How to send DCMI Capture to my own computer display (not LCD ST Board) through USB ?

[FBERT.2]

Hello all,

I have a NUCLEO board (NUCLEO-F756ZG), so with STM32F756ZG.

I used the DCMI interface to grab an image (external synchro , PXCL / HSYNC / VSYNC + D0....D13) from an imager component, working fine.

With STM32CubeIDE, i see that data's are grabbed through DCMI register.

In addition, with "HAL_DCMI_Start_DMA(&hdcmi, DCMI_MODE_SNAPSHOT (uint32_t)FRAME_BUFFER, Im_size);" and "#define FRAME_BUFFER 0x200004ac", i saw in RAM memory that there is some value written.

Consistent value because when imager signal video is low satured ; value are close to '0', when imager video signal is high satured ; value are close to '1', and when imager signal in dynamic value are 'o' and '1' 🙂

After this configuration, i want to SEE THE RAW IMAGE to be sure that grabbed image is correct !

In "AN5020 -Introduction to digital camera interface (DCMI) for STM32 MCUs" from ST, some example with LCD Display ...

In website or ST Forum community, some example with LCD ...

But i have no more hardware and no LCD to see the output image, i only have USB output from NUCLEO (STM32).

In AN5020, looks like we can send datas grabbed from DCMI to USB.

Simple question (but maybe not simple answer) :

How to send data captured from DCMI through USB Nucleo Board, this USB connected to my computer ....and see raw image in my computer display ?

Thanks in advance if someone can help me 🙂

[KDJEM.1 · Accepted solution]

Hello @Florent BERT​ and welcome to the Community 🙂,

You can use the USB port to display capture data or video on your computer display.

For that, I recommend you to take a look to USB_Webcam application in FP-AI-VISION1 package.

FP-AI-VISION1_V3.1.0\Projects\STM32H747I-DISCO\Applications\USB_Webcam

This application enables the STM32H7 to act as a USB Video Camera device. Native USB video driver support is provided with Windows, Ubuntu and macOS.

You can get inspired from this example to send data captured from DCMI through USB.

I hope this help you!

When your question is answered, please close this topic by choosing Select as Best. This will help other users find that answer faster.

Kaouthar

[FBERT.2]

Hello @KDJEM.1,

Thanks for your answers.

At this moment, quite complex for me to do what you said.

But, i bought 2 NUCLEO daughter board (IKS02 & GFX02) to learn more abouit STM32H7 before trying what you said.

At this moment, IKS02 work well with UNICLEO, but GFX032 does'nt works ..

I will post a specific questions regarding GFX02.

Thanks,

Regards,

[FBERT.2]

Hello @KDJEM.1 KDJEM.1,

I've tried FP-AI-VISION1_V3.1.0 with Discovery + B-CAMS-OM(5640) Hardware.

I'm surprised to see that we can't go over 640*480 resolution with 15FPS maximum.

I would try 640*480 , 60 FPS but not working...

Is there any limitation ? Harware with USB UVC Protocol ?

Thanks for your reply !

Regards,

Florent

[KDJEM.1]

Hello @FBERT.2 ,

I'm not an  FP-AI-VISION1_V3.1.0 expert. But when we need to reach a higher FPS, the pixel clock can be increased using CAMERA_BOOST_PCLK = 1. This increases the OV5640 camera pixel clock as follows:
• 24 MHz for the VGA resolution to reach 15 fps
• 48 MHz for the QVGA resolution to reach 30 fps

Please try to take a look to UM2611.

If you need to get an FPS higher than 30FPS, I advise you to post a specific question regarding FPS.

I hope this can help you!

Kaouthar

[FBERT.2]

Hello @KDJEM.1 ,

Thanks for your reply !

We will make a specific post regarding FPS.

Have a nice day,