TouchGFX Application Shows Black Screen After Bootloader Jump

[jumman_JHINGA]

Hello everyone,

I am working on a custom bootloader for an STM32H743-based TouchGFX project and facing a very strange issue specifically with the TouchGFX application after jumping from bootloader.

STM32H743 Bootloader Successfully Jumps to Simple App but TouchGFX Application Shows Black Screen After Bootloader Jump.

I would appreciate any guidance from people who have experience with STM32H7 + TouchGFX + bootloader integration.

Hardware / Project Details

MCU:

• STM32H743IIT6

Frameworks:

• STM32CubeIDE
• TouchGFX
• FreeRTOS

Peripherals Used in TouchGFX App:

• FMC SDRAM
• LTDC
• DMA2D
• QSPI
• I2C
• TIM2

External Memories:

• SDRAM framebuffer at 0xD0000000
• QSPI assets at 0x90000000

Bootloader Functionality

The bootloader:

• Initializes USB Host + FATFS
• Detects pendrive
• Reads image.bin and extflash.bin
• Programs internal flash and external QSPI successfully
• Uses APPLICATION_ADDRESS = 0x08040000
• After flashing, bootloader jumps to application

Important:

• Simple LED blinking application works correctly through the same jump function
• Only TouchGFX application fails

Symptoms

1. TouchGFX application works perfectly when flashed using STM32CubeProgrammer directly.
2. But after bootloader flashing + jump:
   • Display stays completely black
   • No GUI appears
   • No LED toggles inside main()
   • HardFault / MemFault / BusFault handlers are NOT entered
   • Application seems to die before reaching main()
3. If same binary is programmed manually via CubeProgrammer:
   • GUI works correctly even after reset

This strongly suggests:

• The binary itself is valid
• Flashing process mostly works
• Problem happens specifically during bootloader jump/startup

Application Linker Configuration

Application FLASH origin:

FLASH (rx) :
ORIGIN = 0x08040000

Vector table offset in system_stm32h7xx.c:

#define USER_VECT_TAB_ADDRESS
#define VECT_TAB_OFFSET 0x00040000U

Framebuffer sections:

BufferSection (NOLOAD) > SDRAM
BitmapCacheSection (NOLOAD) > SDRAM1
ExtFlashSection > QSPI

Stack pointer at application start:

• 0x24000000 region (AXI SRAM)

Current Jump Function

Current jump code:

typedef void (*pFunction)(void);

void Jump_To_User_Application(void)
{
    uint32_t appStack;
    uint32_t appEntry;

    appStack = *(__IO uint32_t*)APPLICATION_ADDRESS;
    appEntry = *(__IO uint32_t*)(APPLICATION_ADDRESS + 4);

    if (((appStack & 0xFF000000) == 0x24000000) ||
        ((appStack & 0xFF000000) == 0x20000000))
    {
        __disable_irq();

        SysTick->CTRL = 0;
        SysTick->LOAD = 0;
        SysTick->VAL  = 0;

        for (uint32_t i = 0; i < 8; i++)
        {
            NVIC->ICER[i] = 0xFFFFFFFF;
            NVIC->ICPR[i] = 0xFFFFFFFF;
        }

        HAL_MPU_Disable();

        SCB_DisableICache();
        SCB_DisableDCache();

        __DSB();
        __ISB();

        SCB->VTOR = APPLICATION_ADDRESS;

        __set_MSP(appStack);

        pFunction JumpToApp;
        JumpToApp = (pFunction)(appEntry);

        JumpToApp();
    }
}

Debugging Already Done

1. Verified linker FLASH origin = 0x08040000
2. Verified VECT_TAB_OFFSET = 0x00040000U
3. Verified application vector table exists at 0x08040000
4. Verified MSP points to 0x24000000 region
5. Verified TouchGFX binary works when flashed manually
6. Added LED toggles between all init calls in main()
7. Added HardFault / BusFault / MemFault handlers with LED blinking
8. Application never reaches main() after bootloader jump
9. Fault handlers are also never reached
10. Simple non-TouchGFX LED application works correctly with same jump function

Main Question

Why would:

• Simple application jump correctly
• But TouchGFX application fail before entering main()

even though:

• linker script is correct
• vector table offset is correct
• binary works through CubeProgrammer
• flash contents appear correct

Could this be related to:

• AXI SRAM stack pointer
• cache state
• MPU state
• SDRAM/FMC state
• incorrect binary flashing alignment
• Thumb bit/reset vector issue
• startup code incompatibility after bootloader jump

Has anyone successfully implemented STM32H7 bootloader + TouchGFX application jump reliably?

Any suggestions would be greatly appreciated.

Thank you.