STM32F750 800x480 LCD causing artifacts

Thread Starter

ashkarmalik

Joined Jul 1, 2012
112
What is the problem with this display, I am using the STM32F7508-DK With 800x480 Display but I am getting artifacts when using the transition function in touch gfx

I am using TST070CBOT-01P Along with STM32F7508-DK using RGB Interface , I have wired the jumpers with the display to the corresponding pins and everything works fine in static mode, But when transition begins then the Display shows artifacts as shown in video.

Interface- RGB 24 bits

MCU - 200 MHZ

TFT Clock- 30 MHZ
 

MrChips

Joined Oct 2, 2009
30,708
Describe what you mean by artifacts.
What should we be seeing when it is working properly?
What colour should the screen be?
 

Thread Starter

ashkarmalik

Joined Jul 1, 2012
112
Describe what you mean by artifacts.
What should we be seeing when it is working properly?
What colour should the screen be?
When the slide transition begins from red to blue or any other colour then the screen shows abrupt sliding of 2nd colour as I have attached in the previous video which shows the loop transition.
 

macman23

Joined Jan 6, 2023
13
Make sure that the power supply to the display is adequate, and that the supply voltage is within the operating range specified in the datasheet. This could cause an issue
 

nsaspook

Joined Aug 27, 2009
13,080
Yes the orignal one is working fine ,If I limit the Resolution on 800x480 lcd to 480x 272 then the transition seems to be fine
Usually the display driver makes display memory page update calculations based on resolution. You might need to redefine the display type/resolution in a driver file somewhere.
 

Thread Starter

ashkarmalik

Joined Jul 1, 2012
112
Usually the display driver makes display memory page update calculations based on resolution. You might need to redefine the display type/resolution in a driver file somewhere.
I have tried the same setup with STM32F429 MCU with 800x480 Display and everything looks great on that, but I am unable to get it work perfectly on STM32F750.
 

Thread Starter

ashkarmalik

Joined Jul 1, 2012
112
Make sure that the power supply to the display is adequate, and that the supply voltage is within the operating range specified in the datasheet. This could cause an issue
I am trying to give the board external power, will let you know in sometime.
 

nsaspook

Joined Aug 27, 2009
13,080
Yes, I have provided an external power source now, But the same problem persists.
Software is same too, Display is also same.
Just a guess.
The Cortex-M7 is a dual issue superscalar CPU with I/D caching while the Cortex-M4 that can only run a single instruction with a simple cache. Your video shows blocks from what looks like a video memory fill operation. So there might be a memory cache issue with a possible hardware graphics accelerator that's not being handled properly in the M7 at that resolution. Is there a specific M7 version of the display driver?

Try setting the resolution to something that's a factor of 64 like 832 x 480.
 

Thread Starter

ashkarmalik

Joined Jul 1, 2012
112
Just a guess.
The Cortex-M7 is a dual issue superscalar CPU with I/D caching while the Cortex-M4 that can only run a single instruction with a simple cache. Your video shows blocks from what looks like a video memory fill operation. So there might be a memory cache issue with a possible hardware graphics accelerator that's not being handled properly in the M7 at that resolution. Is there a specific M7 version of the display driver?

Try setting the resolution to something that's a factor of 64 like 832 x 480.
I have tried the requested resolution on the system but still, the problem is same.
The Graphics drive is an ST proprietor hardcoded ChromART DMA2D Accelerator
 

MrChips

Joined Oct 2, 2009
30,708
I’m with spook. It would appear to be a graphics memory update problem. Maybe the ChromART interface has not been optimized for that display.
 

Thread Starter

ashkarmalik

Joined Jul 1, 2012
112
Are there GUI demo apps for that board, display hardware and display resolution that work correctly? Try turning off hardware graphics acceleration to force software updates.
I have tried to disable the accelerator but it didn't work either,I made a basic full colour screen and shifted one screen to another screen with a change of colour but there are these missing colour blocks.
 

nsaspook

Joined Aug 27, 2009
13,080
I have tried to disable the accelerator but it didn't work either,I made a basic full colour screen and shifted one screen to another screen with a change of colour but there are these missing colour blocks.
Does 640 x 480 work?

I don't have the hardware or specific experience with that system so I'm at the end of what I can recommend. If we assume the hardware and connections are correct then there should be a working ST demo for it.
https://www.st.com/resource/en/appl...resh-an-lcdtft-display-stmicroelectronics.pdf
 
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