USBX CDC for the stm32u5 in standalone (no RTOS) problem

[ckoec]

Hello,

I implemented a virtual com port using the usbx stack for the stm32U575 in standalone mode and it basicaly works.

My problem is that I just can't put more than 8 bytes in the TX buffer at the time. If I do the program gets stuck (in the main loop)

I tried both: ux_device_class_cdc_acm_write_with_callback and ux_device_class_cdc_acm_write_run

but they only work when the buffer length is less than 8 bytes.

I have the following code in app_usbx_device.c:

  /* USER CODE BEGIN MX_USBX_Device_Init1 */

  /* Initialize the USB Peripheral */
	MX_USB_OTG_FS_PCD_Init();
  
	HAL_PCDEx_SetRxFiFo(&hpcd_USB_OTG_FS, 0x80);
	HAL_PCDEx_SetTxFiFo(&hpcd_USB_OTG_FS, 0, USBD_MAX_EP0_SIZE / 4);
	HAL_PCDEx_SetTxFiFo(&hpcd_USB_OTG_FS, 1, USBD_CDCACM_EPIN_FS_MPS / 4);
	HAL_PCDEx_SetTxFiFo(&hpcd_USB_OTG_FS, 2, USBD_CDCACM_EPINCMD_FS_MPS / 4);
  
  
	/* Link the USB drivers with the USBX DCD and check if it return error */ 
	if(ux_dcd_stm32_initialize((ULONG)USB_OTG_FS, (ULONG)&hpcd_USB_OTG_FS) != UX_SUCCESS){
			  Error_Handler();
	}

	/* Start the PCD Peripheral */
	HAL_PCD_Start(&hpcd_USB_OTG_FS);
  
  /* USER CODE END MX_USBX_Device_Init1 */

And in ux_device_cdc_acm.c (with callback):

VOID USBD_CDC_ACM_Activate(VOID *cdc_acm_instance)
{
  /* USER CODE BEGIN USBD_CDC_ACM_Activate */
	cdc_acm = (UX_SLAVE_CLASS_CDC_ACM*) cdc_acm_instance;

	UX_SLAVE_CLASS_CDC_ACM_CALLBACK_PARAMETER cdc_acm_slave_callback;
	   
	cdc_acm_slave_callback.ux_device_class_cdc_acm_parameter_read_callback = USBX_cdc_acm_device_read_callback;
    cdc_acm_slave_callback.ux_device_class_cdc_acm_parameter_write_callback = USBX_cdc_acm_device_write_callback;
    ux_device_class_cdc_acm_ioctl(cdc_acm, UX_SLAVE_CLASS_CDC_ACM_IOCTL_TRANSMISSION_START, (VOID*)&cdc_acm_slave_callback);
	
  /* USER CODE END USBD_CDC_ACM_Activate */

  return;
}

I was wondering if the routine, which empties the buffer doesn't get called in standalone mode or if I missed something in the init of the stack.

Thank you in advance for your input !

[FBL]

Hi @ckoec 

Have you tried this example ST-TOMAS-Examples-USB/U5_USBX_VCP_Standalone

Add debugging prints to trace and identify where it gets stuck. This can help you pinpoint the exact location of the issue. Here for example, you can see a circular buffer handling.

void HAL_UART_RxCpltCallback(UART_HandleTypeDef *huart)
{
	  EventFlag |= RX_NEW_RECEIVED_DATA;

	    /* Increment the UserTxBufPtrIn pointer */
	  UserTxBufPtrIn++;

	  /* Rollback the UserTxBufPtrIn if it equal to APP_TX_DATA_SIZE */
	  if (UserTxBufPtrIn == APP_TX_DATA_SIZE)
	  {
	    UserTxBufPtrIn = 0;
	  }

	  /* Start another reception: provide the buffer pointer with offset and the buffer size */
	  if (HAL_UART_Receive_IT(uart_handler, (uint8_t *)UserTxBufferFS + UserTxBufPtrIn, 1) != HAL_OK)
	  {
	    /* Transfer error in reception process */
	    Error_Handler();
	  }
}

[ckoec · Accepted solution]

Thank you for your answer !

I compared the example with my code and I noticed that the TX buffers sizes were not correct.

This works:

HAL_PCDEx_SetRxFiFo(&hpcd_USB_OTG_FS, 0x80);
HAL_PCDEx_SetTxFiFo(&hpcd_USB_OTG_FS, 0, 0x10);
HAL_PCDEx_SetTxFiFo(&hpcd_USB_OTG_FS, 1, 0x20);
HAL_PCDEx_SetTxFiFo(&hpcd_USB_OTG_FS, 2, 0x10);