Hi ST Community, @mƎALLEm ,
I really can’t thank you enough for the help. I was honestly struggling to figure this out on my own, and it was stressing me out. Having you step in and guide me through it means a lot. I’m so glad you’re part of this community I really needed this.
Actually I need some more help on the same topic as I am working on executing code from external SDRAM on STM32H563 using FMC + SDRAM Bank1.
Currently, SDRAM initialization works correctly when everything is initialized from main() using CubeMX generated HAL functions:
- MX_FMC_Init()
- HAL_SDRAM_Init()
- DrvSDRAM_Init()
In this case:
- SDRAM read/write works correctly
- code can be copied to SDRAM using memcpy()
- functions placed in SDRAM section can execute successfully
I am using a scatter file section similar to below:
; *************************************************************
; *** Scatter-Loading Description File generated by uVision ***
; *************************************************************
LR_IROM1 0x08000000 0x00200000 { ; load region size_region
ER_IROM1 0x08000000 0x00200000 { ; load address = execution address
*.o (RESET, +First)
*(InRoot$$Sections)
.ANY (+RO)
.ANY (+XO)
}
RW_IRAM1 0x20000000 0x000A0000 { ; RW data
.ANY (+RW +ZI)
}
RW_IRAM3 0xC0000000 0x002C0000 { ; SDRAM 3MB RAM is used as HEAP area
startup_stm32h563xx.o (HEAP)
}
ER_IRAM5 0xC0200000 0x00000200 { ; SDRAM: User Application Code (2 MB)
;.ANY0 (+RW +ZI)
*(.user_app_code)
}
}
And code section example:
void SDRAM_LED_Task(void) {
while (count<=10) {
HAL_GPIO_TogglePin(GPIOB, GPIO_PIN_0);
HAL_Delay(500);
count++;
}
count=0;
}
The problem starts when I try to initialize FMC + SDRAM before main() from SystemInit().
My actual requirement is:
- initialize SDRAM before main()
- move heap/stack into SDRAM
- support scatter loading/runtime sections in SDRAM
- eventually execute application code directly from SDRAM
I tried two approaches inside SystemInit():
1. Calling HAL-based initialization
- HAL_Init()
- SystemClock_Config()
- MX_FMC_Init()
2. Pure register-level initialization
- RCC configuration
- FMC clock enable
- GPIO AF12 configuration
- SDCR/SDTR setup
- SDRAM command sequence
- refresh programming
- MPU configuration
In both cases I am not able to achieve stable SDRAM execution before main().
I already verified that:
- SDRAM command sequence works correctly
- SDRAM works correctly from main()
- MPU executable region configuration is added
- ICACHE invalidation is also attempted
I also replicated the same initialization sequence used internally by HAL for:
- FMC_SDRAM_Init()
- FMC_SDRAM_Timing_Init()
- FMC enable sequence
- SDRAM mode register sequence
But execution from SDRAM before main() is still failing.
I referred to STM32H7 examples and ST forum discussions mentioning that SDRAM should be initialized before main() for scatter loading use-cases, but I could not find any official STM32H5 example demonstrating:
- SDRAM initialization in SystemInit()
- heap/stack relocation to SDRAM
- executing code from SDRAM before main()
Could someone please clarify:
1. What is the correct initialization order on STM32H5 for:
- clocks
- FMC
- GPIO
- MPU
- ICACHE/DCACHE
when SDRAM must be usable before main()?
2. Is it officially supported/recommended to call HAL initialization functions from SystemInit()?
3. Are there any HAL/FMC dependencies on:
- SysTick
- interrupts
- HAL internal state
- cache state
which prevent SDRAM initialization before main()?
4. Is there any official STM32H5 example available for:
- scatter loading to SDRAM
- heap/stack in SDRAM
- executing code from SDRAM
Any guidance would be very helpful.
Also i have attached some files for your reference ..
Again Thank you for the help!!!
Regards,
Shashank k.
