Relocating frame buffer to internal SRAM

[Andrew Stevenson]

Posted on August 07, 2017 at 11:54

Hello everyone,

I am attempting to relocate the frame buffer of the 'STemWin_HelloWorld' supplied with the STM32F429 Discovery kit. I would like to use the internal SRAM instead of the external SDRAM. Our project only requires 240x320 8 BPP so the SDRAM is not required.  

Has anyone any experience with how to do this?

My steps so far are based on the demo code at C:\STM32Cube_FW_F4_V1.16.0\Projects\STM32F429I-Discovery\Applications\STemWin\STemWin_HelloWorld. I am running the example code on the actual Discovery kit.

I changed the &sharpdefine LCD_LAYER0_FRAME_BUFFER in LCDConf_stm32f429i_disco_MB1075.c to the address of the 112KB SRAM which is 0x2000 0000 (page 85 of en.DM00071990.pdf).

When I run the code on the debugger the program stops in the HardFault_Handler() and the call stack is indicating it failed after CUSTOM_FillRect() calls DMA2D_FillBuffer().

Any suggestions gratefully received.

Regards,

Andrew.

#sram #ltdc #stm32f429-disco #stm32f429 #sdram

[markus239955_stm1_stmicro_com · Accepted solution]

Posted on August 10, 2017 at 05:35

During compilation, variables are located in the SRAM area and you can not predict where the are located.

Best practise would be to allocate the frame buffer as a array, too.

uint8_t myframebuffer[320*240];

Then create a pointer

uint8_t *ptr_myframebuffer = &myframebuffer[0];

After initialisation of the LTDC with the default memory location, set the framebuffer to the array.

HAL_LTDC_SetAddress(&hltdc, (uint8_t)ptr_myframebuffer, 0);

Adjust the variable names to your needs.

You can monitor the framebuffer location with STMStudio. The value might cange with every compilation of your project.

Best regards,

Markus.

[Andrew Stevenson]

Posted on August 16, 2017 at 11:25

Markus,

Thank you for your reply, I have it working now. I also had to change the colour depth to L8 to avoid a hard fault when the display was turned on.

Best regards,

Andrew.

[mstfa.okcu1]

Andrew Stevenson,

How did you make changes to the LCDConf_stm32f429i_disco_MB1075 file? I tried the same method, but I had problems. I've changed the LCD_LAYER0_FRAME_BUFFER to 0x20000000. Can you please help me?