What is the cause of the screen shift?

[MPast.1]

Hi All,

Im working with a Custom board using STM32h743 and an RGB Display with ST7796 driver.

I'm configuring SPI to send the right settings to the display for working with RGB pins on LTDC.

In effect I done the 90% of work but I don't understand the reason of the effect on the below image:

Display draw the screen with wrong pixels: it seems shifted.

The original screen created with TouchGFX Designer is:

Whitch parameter is the cause of this effect?

Does someone has some suggestions?

Thanks a lot?

 

 

 

[Osman SOYKURT]

Hello @MPast.1 ,

Where are your assets stored?
And which compiler do you use?
Do you flash your board with STM32CubeProgrammer?

[MPast.1]

HI @Osman SOYKURT ,

My assets are stored inside an external QSPI memory and fetch by QSPI mapping mode.

At the moment I don't remember the exact version of the compiler but is the default version present on the latest stm32CubeIDE 1.15.0. and I'm programming the firmware using debugger functions on STM32CudeIde.

(only for explanation, this experimentation board was used correctly with the previous IDE (1.13.x) and it works correctly with another RGB display - It run at the first try without any problems).

Thinking about the display effect, it seems not a problem on compiler or SW configuration, but instead an hardware configuration (maybe front/back - vertical/horizontal porch - signals polarity or similar). In this case what's the effect in case front/back porch are not setted correctly? Should I see the pixel shifted like in my case?

Comparing display and ST7796 datasheets and stm32cube configurator, it seems everything configured correctly.

 

 

 

[MPast.1]

It was a bad settings on ST7796 sent on SPI.

I solved the problem.