STM32F746G Discovery: What is the difference between CU2 and CU4 in the end?

[Jackiii1989]

Hi there,

I have a STM32F746G Discovery board on which I have developed an application. The application was running fine, there was some strange behaviour, probably some minor bugs, but it looked good.

When I bought a new identical board and flashed the application, the display literally showed some random noise, like this:

I flashed the examples from TouchGFX to see if it made a difference, but I got the same result. My old board is DK32F746G$U2, which works fine, but the new one is DK32F746G$CU4, which renders everything wrong. 

I found a STM post on this link: STM32F746G_Discovery touch screen buttons stop wor... - STMicroelectronics Community, that says there may be different display built-in:

1. CU1 uses - HT043C

2. CU2 uses - GJX043A6 -40D Y

I have no clue what the display is used for CU4 as I could not find any information about it. 

How do I solve this? 
Thanks for the help!!!

[Jackiii1989 · Accepted solution]

Hello @Mohammad MORADI ESFAHANIASL,

You have hit the nail on the head. Now it works!

The problem why the draw function threw an error was probably that it could not get the fonts, texts and the image from the external memory, and with no data it cannot update the framebuffer. Maybe it would be cool to print out some text so the user could see the problem.

What was missing was the quad spi driver, which was not the latest, and the W25Q128J QSPI memory header with all the register definitions.

If someone else has the same problem, this is what you need to do:

1. Copy the latest stm32746g_discovery_qspi.c/stm32746g_discovery_qspi.h files to Drivers-> BSP -> STM32F746G-Discovery (The version I had: Release v2.1.0 ).
2. Create a folder named w25q128j in Drivers-> BSP -> Components and copy the file w25q128j.h into the folder. (The version I had:: Release v1.0.0).
3. Define the USE_STM32746G_DISCO_REVC03 symbol in the preprocessor.

Thanks for the help!!!!