I am using STM32N657 with USBX (MSC device).
The function ux_device_stack_initialize() is returning UX_ERROR, and after debugging inside USBX I found that the failure occurs when USBX tries to allocate endpoint transfer buffers.
The failing code inside USBX is:
#if UX_DEVICE_ENDPOINT_BUFFER_OWNER == 0
/* Obtain some memory. */
endpoints_pool -> ux_slave_endpoint_transfer_request.ux_slave_transfer_request_data_pointer =
_ux_utility_memory_allocate(UX_NO_ALIGN, UX_CACHE_SAFE_MEMORY, UX_SLAVE_REQUEST_DATA_MAX_LENGTH);
/* Ensure we could allocate memory. */
if (endpoints_pool -> ux_slave_endpoint_transfer_request.ux_slave_transfer_request_data_pointer == UX_NULL)
{
status = UX_MEMORY_INSUFFICIENT; //0x12
break;
}
#endif
So the device stack initialize fails because of UX_MEMORY_INSUFFICIENT.
My current USBX memory setup:
#define UX_APP_MEM_POOL_SIZE (128 * 1024) // 128 KB total pool
#define USBX_DEVICE_MEMORY_STACK_SIZE (5 * 1024) // only 5 KB given to USBX
I allocate memory for USBX like this:
tx_byte_allocate(byte_pool, (VOID **) &pointer, USBX_DEVICE_MEMORY_STACK_SIZE, TX_NO_WAIT);
ux_system_initialize(pointer, USBX_DEVICE_MEMORY_STACK_SIZE, UX_NULL, 0);
This means that even though my total pool is 128 KB, USBX actually receives only 5 KB for all internal allocations (endpoint buffers, MSC class buffers, descriptors, etc.).
My question:
Is 5 KB far too small for USBX MSC on STM32N6?
What is the recommended minimum memory size that must be passed to ux_system_initialize() when using MSC (Mass Storage Class)?
From debugging, USBX cannot allocate the MSC endpoint transfer buffers with only 5 KB, so initialization fails with UX_MEMORY_INSUFFICIENT.
I want to know the correct recommended memory size for MSC on STM32N6.
I am using USBX specifically for Mass Storage Device (MSC).
Thank you.
