Display blank in Video Mode (STM32H747I-DISCO & TouchGFX & Custom Display Board)

[MIVA]

Hi,

I'm trying get display working in Video Mode with TouchGFX(STM32H747I-DISCO as development board), but with no awail.

The display board is a custom one (uses ILI9806E driver (no GRAM), which can only work in Video Mode)

Steps I have done so far:

1. Made sure the driver works fine with LCD_DSI_VideoMode_SingleBuffer example. (ILI9806E Standalone)

2. Run the TouchGFX application successfully with original display board w/o any modifications in the code, for sanity check. (OTM8009A Command Mode & TouchGFX)

3. Configured the application based on this documentation: MIPI-DSI Video Mode (ILI9806E & TouchGFX)

4. Run the " HAL_DSI_PatternGeneratorStart(&hdsi, 0, 0);" , which shows the pattern correctly. (ILI9806E & TouchGFX))

5. Scoured through the forum to find out what I'm missing.

Any suggestions what should be the next step(s)? 

[Osman SOYKURT]

Hello @MIVA ,

I'm not a specialist on that part but I'll try to give a help.

It's a good sign that the HAL_DSI_PatternGeneratorStart shows the correct pattern. It sounds like the screen is correctly configured in itself. I guess that the framebuffer is ok since you were able to see it with the old screen, but to  be sure, could you check on memory if your data are here?

I saw a caution note in our Touchgfx documentation on STM32H7 for the display, could you check it?

[MIVA]

Hi @Osman SOYKURT ,

Thank you for the reply. 

I did check the memories and the data is there, as it is with the old screen.

I checked the caution note, both CPU Caches were enabled and there is a callback for both "SCB_EnableICache() and  SCB_EnableDCache()".

Unfortunately the status remains the same, thanks for the help anyway.

[Tesla DeLorean]

Having read the thread I'm not any wiser to what panel is being used, the expected parameters for that, or what's set into the LTDC, DSI or PLLs. Just know its using a ILI9806E

Likely not the memory/caching. Much more likely the clocking and the data pipeline to the display.

Suggest you get the display working in a stand-alone fashion using the examples in the CubeH7 repo, say JPEG examples, SD Card ones or BSP.

Any other reference material for the display being successfully used on any other platform? You could use that to port, or determine minimal working requirements. A working platform? 3 displays? to be sure you're not wasting time on something that demonstrably dead already..

[MIVA]

Hi @Tesla DeLorean,

Thank you for the reply.

Actually it was good to check those stand-alone examples from ChubeH7 repo such as JPEG SD card and BSP examples(which worked fine), as now I think I start to understand where the issue is(=very simple mistake with the MIPI-DSI Video-Mode driver, not with ILI9806E driver itself).