USBX configuration check - potential bug with USBX System Stack Size

[CecilW]

I encountered a potential bug in CubeMXs Configuration Checks for USBX.

I am trying to configure USBX in standalone mode. When i try to increase the value of “USBX System Stack Size” to be higher than 1024 i get a warning that it needs to be lower than the USBX memory pool size, even when this is the case.

Attached is a screenshot with example settings. To reproduce the error set USBX System Stack Size to 1025.
The used MCU is a STM32U385CGTx

Best regards, Cecil
 

 

[Ghofrane GSOURI]

Hello ​@CecilW 

Your contribution is much appreciated.

Issue has been escalated to dev team under internal ticket ID #0064608

As a workaround, generate the project code first, then manually edit app_usbx.h and change:

#define USBX_MEMORY_STACK_SIZE

to the value required by your application.

This allows the desired USBX system stack size to be set even when STM32CubeMX rejects the value in the GUI.

Note: this manual change may be overwritten if the project is regenerated from STM32CubeMX, so it should be reapplied after each code generation

THX

Ghofrane

[TDJ]

Hello ​@Ghofrane GSOURI and ​@CecilW 

I may experience a similar issue with STM32U5G9.
My USBX setup is very basic, only MSC class is enabled - scrsht see below.
USBX memory is configured as follows:

#define USBX_MEMORY_STACK_SIZE       8*1024
#define UX_APP_MEM_POOL_SIZE            256*1024 // max allowed value

No matter how I increase the available memory, function MX_USBX_Host_Stack_Init() fails calling
    ux_host_stack_hcd_register()
        hcd_init_function()
            _ux_hcd_stm32_initialize() - returns status UX_MEMORY_INSUFFICIENT trying to “Allocate the list of eds.” (file ux_hcd_stm32_initialize.c, line 122)

I am clueless.

 

[TDJ]

Update: I found that increasing USBX_MEMORY_STACK_SIZE to min 9 kB helps just to initialize the host. Default value is far too small. Practically 24 kB should be used. See here.
UX_APP_MEM_POOL_SIZE can probably stay as small as 40 kB. See this thread.

Note: CubeMX has a bug. USBX_MEMORY_STACK_SIZE needs to be modified in code. Changing it in Cube MX make no difference, Cube MX does not persist this value. When *.ioc file is open again “USBX System Stack Size” reverts to default 1024.
Needless to say, Cube MX overwrites USBX_MEMORY_STACK_SIZE set in code! It has been already reported here.