Riverdi 12.1" + TouchGFX 4.25 + FATFS not working

[Sasa1234]

Hi everyone,

I am working on a Riverdi 12.1" display board based on STM32H7 with TouchGFX 4.25 generated project.

Environment:

• TouchGFX 4.25

• STM32CubeMX generated project

• STM32CubeIDE

• Riverdi 12.1" board

• STM32H7

• FreeRTOS enabled

• Debugging with ST-LINK

Problem:
BSP_SD_Init() returns MSD_ERROR_SD_NOT_PRESENT.

In main.c:

uint8_t res;

res = BSP_SD_Init();

risultato = res;

if(res != 2)
{
    Error_Handler();
}

The value stored in risultato is:

MSD_ERROR_SD_NOT_PRESENT

Additional important behavior:

When I start a FreeRTOS task that accesses FATFS/SD, the display becomes completely black and TouchGFX no longer shows images.

This is my task:

void StartDefaultTask(void *argument)
{
    FIL file;
    UINT bw;

    for(;;)
    {
        SCB_CleanDCache();
        SCB_InvalidateDCache();

        if(BSP_SD_Init() == MSD_OK)
        {
            if(f_mount(&SDFatFS, SDPath, 1) == FR_OK)
            {
                if(f_open(&file, "log.txt", FA_OPEN_ALWAYS | FA_WRITE) == FR_OK)
                {
                    f_lseek(&file, f_size(&file));

                    char msg[] = "log entry\r\n";
                    f_write(&file, msg, strlen(msg), &bw);
                    f_close(&file);
                }
            }
        }

        osDelay(1000);
    }
}

If I completely comment out this task, TouchGFX works correctly and all images are displayed normally.

So:

• With SD/FATFS task enabled → display becomes black

• With SD/FATFS task disabled → GUI works correctly

Other details:

• SDRAM initialized correctly

• LTDC working before SD task starts

• QSPI memory mapped mode enabled

• FATFS enabled

• MPU configured with SDRAM framebuffer as non-cacheable

MPU configuration:

MPU_InitStruct.BaseAddress = 0xD0000000;
MPU_InitStruct.Size = MPU_REGION_SIZE_8MB;
MPU_InitStruct.IsCacheable = MPU_ACCESS_NOT_CACHEABLE;

Questions:

• Could this be a DCache/MPU coherency issue between TouchGFX and FATFS?

• Is there a known issue with Riverdi BSP + SDMMC + TouchGFX?

• Should SD buffers be placed in a dedicated MPU region?

• Is calling SCB_CleanDCache() and SCB_InvalidateDCache() inside the task causing LTDC framebuffer corruption?

• Is there a recommended STM32H7 cache configuration for TouchGFX + FATFS?

Any suggestion is appreciated.

Thanks.