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Jack3
Jack3
Senior
October 9, 2025
Solved

STM32N6570-DK with FSBL and Appl - mapping external PSRAM in FSBL

  • October 9, 2025
  • 0 replies
  • 480 views

Hello superhero MCU enthusiasts,

I'm playing with the STM32N6570-DK and have created a simple project with an FSBL that initializes the MCU and boots the Appl. Once booted, the Appl flashes a "Hello World" LED.
Both can be loaded to external flash using the STM32CubeProgrammer.

Now, I'm trying to map external PSRAM (XSPI1 -> 0x90000000) inside the FSBL, but it fails.

To do that, I change a line in a file in the FSBL, stm32_extmem_conf.h, line 35 of (PSRAM disabled):

#define EXTMEM_DRIVER_PSRAM 0

Now I try to enable and map the external PSRAM by setting the definition to 1:

#define EXTMEM_DRIVER_PSRAM 1

However, it doesn't succeed.

When debugging I see we land into a HardFault.

The FSBL generates a HardFault when executing SAL_XSPI_EnableMapMode, because the function HAL_XSPI_MemoryMapped fails.
I can't find the cause.
Anyone?
I posted a project here with a short Readme.md:

https://github.com/AngryCarrot61/STM32N6570-DK_004

Note: to see FSBL and Appl working one has to set EXTMEM_DRIVER_PSRAM to 0.
However the goal is to get PSRAM mapped (XSPI1 at 0x90000000).

Flashing:
the debug directories for FSBL and Appl contain a batch file: '0_SigningTool.bat'.
After compiling, run the batch files to sign the binaries.
Using STM32CubeProgrammer we select EL 'MX66UW1G45G_STM32N6570-DK'.
FSBL will be loaded at 0x70000000, and Appl at 0x70100000.
Enjoy!

 

Any help is much apreciated regarding the part to map the PSRAM!

Cheers!

Best answer by Jack3

Thank you very much, I forgot to add the PSRAM into the MPU.
However, the initialization still failes, so I wouldn't be able to access it anyway.
My new STM32N6 MPU configuration:

static void MPU_Config(void)
{
 /*
 * XSPI2 0x70000000 128MB FLASH (1-Gbit Octo-SPI)
 * XSPI1 0x90000000 32MB PSRAM (256-Mbit Hexadeca-SPI)
 */
 MPU_Region_InitTypeDef default_config = {0};
 MPU_Attributes_InitTypeDef attr_config = {0};
 uint32_t primask_bit = __get_PRIMASK();
 __disable_irq();

 /* disable the MPU */
 HAL_MPU_Disable();

 /* create an attribute configuration for the MPU */
 attr_config.Attributes = INNER_OUTER(MPU_WRITE_BACK | MPU_NON_TRANSIENT | MPU_RW_ALLOCATE);
 attr_config.Number = MPU_ATTRIBUTES_NUMBER0;

 HAL_MPU_ConfigMemoryAttributes(&attr_config);

 /* Create a region associated with memory address 0x70000000 */
 /*Normal memory type, code execution allowed */
 default_config.Number = MPU_REGION_NUMBER0;
 default_config.Enable = MPU_REGION_ENABLE;
 default_config.BaseAddress = XSPI2_BASE; /* FLASH 128MB 0x70000000 */
 default_config.LimitAddress = XSPI2_BASE + 0x08000000-1;
 default_config.DisableExec = MPU_INSTRUCTION_ACCESS_ENABLE;
 default_config.AccessPermission = MPU_REGION_ALL_RO;
 default_config.IsShareable = MPU_ACCESS_NOT_SHAREABLE;
 default_config.AttributesIndex = MPU_ATTRIBUTES_NUMBER0;
 HAL_MPU_ConfigRegion(&default_config);

 /* Ensure the FSBL enables MPU access for the PSRAM region before mapping it: */
 default_config.Number = MPU_REGION_NUMBER1;
 default_config.Enable = MPU_REGION_ENABLE;
 default_config.BaseAddress = XSPI1_BASE; /* PSRAM 32MB 0x90000000 */
 default_config.LimitAddress = XSPI1_BASE + 0x02000000-1;
 default_config.DisableExec = MPU_INSTRUCTION_ACCESS_ENABLE;
 default_config.AccessPermission = MPU_REGION_ALL_RW;
 default_config.IsShareable = MPU_ACCESS_INNER_SHAREABLE | MPU_ACCESS_OUTER_SHAREABLE;
 default_config.AttributesIndex = MPU_ATTRIBUTES_NUMBER0;
 HAL_MPU_ConfigRegion(&default_config);

 /* enable the MPU */
 HAL_MPU_Enable(MPU_PRIVILEGED_DEFAULT);

 /* Exit critical section to lock the system and avoid any issue around MPU mechanisme */
 __set_PRIMASK(primask_bit);
}

I still hope to find the problem soon. I'm looking into my PSRAM initialization.
Thanks for helping!

 

UPDATE: I got access to the external PSRAM working from the FSBL.

I added HAL_PWREx_EnableVddIO* lines.

void HAL_MspInit(void)
{
 HAL_PWREx_EnableVddIO2();
 HAL_PWREx_EnableVddIO3();
 HAL_PWREx_EnableVddIO4();
 HAL_PWREx_EnableVddIO5();
}

After the PSRAM test, FSBL launches the application (Appl), which blinks the LEDs.


I updated the repository on github:
https://github.com/AngryCarrot61/STM32N6570-DK_004

Enjoy!

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