Touchgfx DSI Video Mode - LTDC Overflow

[SNare.1]

We are running into some issues getting Touchgfx with DSI Video Mode Running

1. uC - STM32F779BI

2. Display - 720 *1280

3. Display Controller - ST7703

4. No of MIPI Lanes - 2 lanes

5. DSI Host Mode - Video Mode

6. RGB 565

We have been able to communicate with the display to setup the display (LP Mode) but after the initial setup we just get DSI_FIFO_OVF error.

LTDC Settings

No of Layers - 1

Pixel Format - RGB 565

Frame Buffer - Externa 128Mb SDRAM (S42S32400F-6TL) for the supporting the frame buffers.

We recieve the DSI error only when the LTDC Overflow interrupt is enabled. Any suggestions on what could be causing the overflow ? Also I see that Touchgfx examples all use Command Mode with TE, are there any examples to support Touchgfx in DSI Video Mode.

Thank you

[Martin KJELDSEN]

Historically, we've used adapted command mode because of the large displays on the DSI Disco/Eval boards (800x480). I don't think we'll begin producing video mode examples/application templates, even for smaller (e.g. round) displays because command mode allows us to send only what's required to the display. The DSI HOST must not be able to process the data received from the LTDC - Can you double check your configuration?

You say that you only receive the error when the interrupt is enabled - Does that also mean you're not seeing any problems if its not enabled?

/Martin

[MM..1]

When you use external framebuffer, you need properly set speed for LTDC and DSI CLOCK. FMC memory set to top possible.

Teoretical 565 framerate is over 60Hz, but only with internal ram. For external and too in datasheet is 720p 30Hz DSI. Then set LTDC clock to asume this rate.

And to Video Mode DSI you can convert any example some changes...

[mibra.1]

Hi SNare.1, Did you have any luck finding a Dsi video sample for TouchGFX?

[NHo.1]

Hi all,

Please share to me an example TouchGFX with DSI video mode if you can.

Thanks

[MM..1]

@NHo.1​  @mibra.1​  Here is one changed from adapted mode on F469DISCO

[NHo.1]

Hi MM..1,

Thank you very much. I tried it, it works well.

[Martin KJELDSEN]

​You should be able to use the LTDC examples for DSI Video mode, in theory. (Select LTDC from the display interface settings in TouchGFX Generator) and just set up your DSI to video mode.