Bug in STM32CubeMx code generation for CDC Host if length > 64 ?

[JVERN.18]

Hello,

STM32CubeMx for the CDC Host mode, there seems to be a problem in the "static void CDC_ProcessReception (USBH_HandleTypeDef * phost)" function of the "usbh_cdc.c" file if we use the "USBH_CDC_Receive" function (USBH_HandleTypeDef * phost, uint8_t * pbuff , uint32_t length) "with length> wMaxPacketSize (here 64).

Indeed, in the line 36 :

/**
* @brief  This function responsible for reception of data from the device
*  @param  pdev: Selected device
* @retval None
*/
 
static void CDC_ProcessReception(USBH_HandleTypeDef *phost)
{
  CDC_HandleTypeDef *CDC_Handle =  (CDC_HandleTypeDef*) phost->pActiveClass->pData;
  USBH_URBStateTypeDef URB_Status = USBH_URB_IDLE;
  uint32_t length;
 
  switch(CDC_Handle->data_rx_state)
  {
 
  case CDC_RECEIVE_DATA:
 
    USBH_BulkReceiveData (phost,
                          CDC_Handle->pRxData,
                          CDC_Handle->DataItf.InEpSize,
                          CDC_Handle->DataItf.InPipe);
 
    CDC_Handle->data_rx_state = CDC_RECEIVE_DATA_WAIT;
 
    break;
 
  case CDC_RECEIVE_DATA_WAIT:
 
    URB_Status = USBH_LL_GetURBState(phost, CDC_Handle->DataItf.InPipe);
 
    /*Check the status done for reception*/
    if(URB_Status == USBH_URB_DONE)
    {
      length = USBH_LL_GetLastXferSize(phost, CDC_Handle->DataItf.InPipe);
 
      if(((CDC_Handle->RxDataLength - length) > 0U) && (length > CDC_Handle->DataItf.InEpSize))
      {
        CDC_Handle->RxDataLength -= length ;
        CDC_Handle->pRxData += length;
        CDC_Handle->data_rx_state = CDC_RECEIVE_DATA;
      }
      else
      {
        CDC_Handle->data_rx_state = CDC_IDLE;
        USBH_CDC_ReceiveCallback(phost);
      }
 
#if (USBH_USE_OS == 1U)
      phost->os_msg = (uint32_t)USBH_CLASS_EVENT;
#if (osCMSIS < 0x20000U)
      (void)osMessagePut(phost->os_event, phost->os_msg, 0U);
#else
      (void)osMessageQueuePut(phost->os_event, &phost->os_msg, 0U, NULL);
#endif
#endif
    }
    break;
 
  default:
    break;
  }
}

We see that the test "(length> CDC_Handle-> DataItf.InEpSize)" is never true because "length" is always less than or equal to (actually equal to) "InEpSize" which is initialized with "wMaxPacketSize", here 64 .

It would probably be necessary to change the test for "... && (length == CDC_Handle-> DataItf.InEpSize))" or "... && (length> = CDC_Handle-> DataItf.InEpSize))"

[JMeye.2]

Hey I just had a similar thought. Did you confirm this as a problem in the end?

Also I notice that USBH_BulkReceiveData uses CDC_Handle->DataItf.InEpSize as a size but with CDC_Handle->pRxData as buffer so would this require

USBH_CDC_Receive to be called with length a multiple of CDC_Handle->DataItf.InEpSize?