STM32F746G_Discovery touch screen buttons stop working on hard reset

[HTher.2]

Hello,

Using a STM32F746G-Discovery board and TouchGFX 4.20.0, the on-screen buttons of the "Button example" as distributed with the TouchGFX package do not respond after the board is reset via the reset button or on a power-up reset. When flashing the code and the ST-Link debugger resets the processor, it works fine, as well as when the processor is reset with STM32CubeProgrammer. Also works as expected under debugger control.

The processor is running fine, as established through a simple LED flashing routine in the HAL_TIM_PeriodElapsedCallback ISR.

Has this "feature" been seen elsewhere? Any ideas to the cause of this?

[DZhan.9]

I got exactly the same issue. Did you manage to fix it?

[HTher.2]

DZhan.9, sadly NO, the problem is persisting.

[Romain DIELEMAN]

Hi,

I unfortunately don't have the board with me so we'll have to rely on another user or ST employee to give it a try, but could you share your board revision so that we know exactly which model it is? This should be written on a white sticker on your board.

This "button example" you are referring to is the "button example" available in TouchGFX Designer right ? Or is it from some sort of Out of the Box package ? Did you face a similar bug with other demos/examples available in TouchGFX Designer ?

Have you tried with TouchGFX 4.19 or older by any chance ?

/Romain

[LBend.1]

Romain, 

Comparing my program on a CU1 and CU2, I've tried TouchGFX 4.16.0, TouchGFX 4.20.0, and TouchGFX 4.21.4. The CU1 version always works, and the CU2 always locks up. As mentioned in my other reply, the only difference I can find is the following touchscreen component differences:

1. CU1 uses - HT043C

2. CU2 uses - GJX043A6 -40D Y

Do you have any other insight that might help?

Thanks!

[HTher.2]

Romain,

I can spot three white stickers on the board, the details as follows:

Sticker 1 (front):

STM32F746G-DISCO

DK32F746G$CU2

Sticker 2 (back):

MB1191-F746-C01

C222104827

Sticker 3 (back):

400725 1801 004827 2221

The problem manifested itself in my own application and as a fallback I tried the Button Example as supplied with TouchGFX 4.2.0: This example is simple enough to only address the issues I am experiencing.

The board setup is only supported from TouchGFX4.20.0 as described by the board description, so no, I have not tried older versions.

When the compiled application is deployed with Debug (-Og) optimization, it operates as expected after a debugger reset. Any other reset, reset button or power cycle makes the button inoperable. When the application is deployed with Size (-Os) optimization and no debug support, it fails from the onset, no touch screen activity.

I can add that TouchGFX 4.20.0 seems to use STM32CubeMX V6.5.0 using FW_F7 V1.16.2 to generate the setup. I am using STM32CubeIDE V1.10.1 that includes STM32CubeMX V6.6.1 and supports FW_F7 V1.17.0. I am still compiling with STM32Cube FW_F7 V1.16.2 (i.e. no migration).

[LBend.1]

Hello, 

I've been fighting this same issue for awhile now. This is what I've noticed:

1. My program works on STM32F746G-DISCO, DK32F746G$CU1. On reset and/or power on reset no issues. The touchscreen continues to work fine. 

2. The same program works only after flashing the first time onto a STM32F746G-DISCO, DK32F746G$CU2. On reset and/or power on reset the touchscreen fails to realize any touch events and will not move. I originally tried TouchGFX 4.16.0 with my original program but had to update since there was a flash verification error that manifested after programming. When I updated to TouchGFX 4.20.0 the flash verification error went away, but then the failing touchscreen error manifested. I've since updated to TouchGFX 4.21.4 and STM32CubeMX V6.8.1 and am experiencing the same issues.

3. Of the boards we have, every CU1 version works, and every CU2 version experiences the same issue.

The only differentiating schematic/pcb difference I've been able to find is the screen LCD controller. I believe the data sheets are the ones attached. https://community.st.com/t5/touchgfx-and-gui-mcu/stm32f746g-disco-display-datasheet/m-p/472172 

1. CU1 uses - HT043C

2. CU2 uses - GJX043A6 -40D Y

Has anyone else experienced/seen similar things or found a solution?

Thanks!