STemWin: MPU configuration for SDRAM and LTDC
Hello to everyone!
Recently I was faced with a problem using GUI_GIF_Draw() function. That function works properly with a graphical memory assigned to internal RAM using GUI_ALLOC_AssignMemory() and fails if memory assigned to SDRAM.
My chip is STM32F777ZI.
SDRAM is
MT48LC32M16A2
.My old thread:
https://community.st.com/0D50X00009XkWIZSA3
I suggest my problem is that MPU not properly configured for SDRAM regions. In LTDC manual (AN4861) there is a chapter with special recommendations for Cortex-M7 at page 81. This chapter containing an information about MPU regions configuration.
I created following regions:
Region0: defines the whole SDRAM memory (64 MByte in my case);
(graphical memory (aMemory) assigned to STemWin using
GUI_ALLOC_AssignMemory() (&sharpdefine GUI_NUMBYTES 0x2000000) and allocated at lower 32 Mbyte of SDRAM. It has a start address 0xC000000 as SDRAM connected through FMC Bank1);
Region1: defines the framebuffer memory (&sharpdefine LCD_LAYER0_FRAME_BUFFER ((uint32_t)0xC2000000)); upper 32 Mbyte of SDRAM;
First I configured following attributes:
Region0: normal memory; cacheable; write-through; full access; enable execution.
Region1: normal memory; cacheable; write-through; full access; execute never.
Here is some code:
const unsigned char _acpictgif[4790UL + 1] = {...GIF array...};
int main(void)
{
MPU_Config();
SCB_EnableICache();
SCB_EnableDCache();
...
// Code sections with MCU, HAL, System clock, GPIO, Peripherals configuration, nothing interesting...
...
// Start showing the GIF
GUI_Init();
GUI_Clear();
status = GUI_GIF_Draw(_acpictgif, 4790UL + 1, 0, 0);
while (1) {
GUI_Delay(100);
}
}
void MPU_Config(void)
{
LL_MPU_Disable();
LL_MPU_ConfigRegion(LL_MPU_REGION_NUMBER0, 0x0, 0xC0000000, LL_MPU_TEX_LEVEL0|LL_MPU_REGION_SIZE_64MB|LL_MPU_REGION_FULL_ACCESS|
LL_MPU_INSTRUCTION_ACCESS_ENABLE|LL_MPU_ACCESS_NOT_SHAREABLE|
LL_MPU_ACCESS_CACHEABLE|LL_MPU_ACCESS_NOT_BUFFERABLE);
LL_MPU_EnableRegion(LL_MPU_REGION_NUMBER0);
LL_MPU_ConfigRegion(LL_MPU_REGION_NUMBER1, 0x0, 0xC2000000, LL_MPU_TEX_LEVEL0|LL_MPU_REGION_SIZE_32MB|LL_MPU_REGION_FULL_ACCESS|
LL_MPU_INSTRUCTION_ACCESS_DISABLE|LL_MPU_ACCESS_NOT_SHAREABLE|
LL_MPU_ACCESS_CACHEABLE|LL_MPU_ACCESS_NOT_BUFFERABLE);
LL_MPU_EnableRegion(LL_MPU_REGION_NUMBER1);
LL_MPU_Enable(LL_MPU_CTRL_PRIVILEGED_DEFAULT);
}
Got an error.
status = 1:
Next I reconfigured regions to WBWA:
void MPU_Config(void)
{
LL_MPU_Disable();
LL_MPU_ConfigRegion(LL_MPU_REGION_NUMBER0, 0x0, 0xC0000000, LL_MPU_TEX_LEVEL1|LL_MPU_REGION_SIZE_64MB|LL_MPU_REGION_FULL_ACCESS|
LL_MPU_INSTRUCTION_ACCESS_ENABLE|LL_MPU_ACCESS_NOT_SHAREABLE|
LL_MPU_ACCESS_CACHEABLE|LL_MPU_ACCESS_BUFFERABLE);
LL_MPU_EnableRegion(LL_MPU_REGION_NUMBER0);
LL_MPU_ConfigRegion(LL_MPU_REGION_NUMBER1, 0x0, 0xC2000000, LL_MPU_TEX_LEVEL1|LL_MPU_REGION_SIZE_32MB|LL_MPU_REGION_FULL_ACCESS|
LL_MPU_INSTRUCTION_ACCESS_DISABLE|LL_MPU_ACCESS_NOT_SHAREABLE|
LL_MPU_ACCESS_CACHEABLE|LL_MPU_ACCESS_BUFFERABLE);
LL_MPU_EnableRegion(LL_MPU_REGION_NUMBER1);
LL_MPU_Enable(LL_MPU_CTRL_PRIVILEGED_DEFAULT);
}
And got this one. status = 0. No errors but the GIF contains distortion artifacts:
And again I reassigned aMemory for STemWin to internal RAM and got a fine picture. status = 0:
Seems that MPU regions not properly configured in case of aMemory allocation in SDRAM.
Can anyone tell a proper MPU configuration?
Thanks for your time.
#mpu #stemwin #sdram #ltdc #gif