Converting from DSI LCD to RGB (parallel) LCD

[SShai.1]

Hi,

I am using the STM32H757-EVAL kit and TouchGFX with IAR Workbench. I have opened up the STMH747-EVAL kit project within TouchGFX and used it successfully with the DSI LCD. I however need to use a parallel RGB LCD for my needs. I have created a converter cable to interface the RGB LCD to the EVAL kit. I have modified the code to use the LTDC peripheral and can control the RGB LCD (turn it on, change background color etc). However when I use it with TouchGFX I encounter issues:

1. Open project in TouchGFX and create background color (Yello) and a simple text box.
2. Run Target with DSI LCD installed on EVAL kit.
3. EVAL kit runs ok.
4. Replace DSI LCD with RGB LCD on EVAL kit.
5. Program modified code (IAR) using STProgrammer onto EVAL kit.
6. At this stage the RGB LCD shows the background screen and text box exactly as shown on TouchGFX. If I reset the EVAL kit (using boards' reset button) the screen comes back. However if I unplug and plug back in the power cord to the EVAL kit, the screen doesn't show (LCD shows star pixels). Also any animations or screen changes I develop into TouchGFX dont get displayed on RGB LCD (they work on DSI LCD).

Any thoughts on the issue?

What is the established/documented procedure for changing code to switch from DSI LCD to RGB LCD? This info used to be available on the previous TouchGFX support site but I cant find the info on the new page that they have moved to.

[Alexandre RENOUX]

Hello,

To change from DSI to LTDC, you can refer to the following links to help you:

https://support.touchgfx.com/docs/development/touchgfx-hal-development/touchgfx-architecture

https://support.touchgfx.com/docs/development/board-bring-up/board-introduction

I don't know your screen and it is usually the main issue when changing from one screen to another. Have you tried to reset in debug mode ?

Resetting works but unplugging does not work so it's probably due to one part wrongly initialized and this should be the display as you only changed that part.

/Alexandre

[SShai.1]

Hi Alexander,

The device I am using is NHD-5.0-800480TF-ATXL#.

Note that the initialization of the LCD is fine since when I initialize Layer0 using the QSPI address the LCD works with the reset button and plug reset.

Also do you know how to initiate debug mode in IAR Workbench? Note that I am using the code generated by TouchGFX for the STM32F7 eval kit which only provides one Workspace in IAR Workbench

Thanks.

[Alexandre RENOUX]

Hello,

To start the debug mode, you first need to download the code using STCubeProgrammer. Then, when the code is donwloaded successfully, you start debug in IAR by clicking on the debug without downloading button.

/Alexandre

[k_c2024]

Hi,

I am also using STM32h757 board, i opened up the STMH747-EVAL kit project within TouchGFX but not working on my board. I am not getting display as i am designing in touchgfx.

Is h747 fully compatible with h757, or some changes needed ?

@Osman SOYKURT