Question about USBH_BulkReceiveData() Usage

[kroesswang_thomas]

Posted on October 23, 2012 at 15:30

Hello!

I'm currently working on a project using the STM32F4 Discovery board as a CDC-Host. I have succesfully enumerated my usb device and also successfully used USBH_BulkSendData(). But now I'm unsure about how to use USBH_BulkReceiveData() correctly. Do I have to execute it before polling (HCD_GetURB_State(pdev , MSC_Machine.hc_num_in) == URB_DONE), or do I have to poll before executing the receive-handle? When I execute USBH_BulkReceiveData() first, the STM32 goes into an infinite USB-interrupt loop. But when I poll first the URB_State always stays URB_IDLE. I have studied the MSC Host example file but it doesn't provide an answer to my question.

[dmakhrov9]

Posted on October 23, 2012 at 16:15

This modified code from MSC worked for me. But that was pain. Still do not understand how it functions 🙂

static USBH_Status USBH_MSC_Handle(USB_OTG_CORE_HANDLE *pdev ,                                    void   *phost) {   USBH_HOST *pphost = phost;   USBH_Status status = USBH_BUSY;   uint8_t appliStatus = 0;   uint16_t tempInt;        if(HCD_IsDeviceConnected(pdev))   {        switch(USBH_MSC_BOTXferParam.MSCState)     {     case USBH_MSC_BOT_INIT_STATE:       USBH_MSC_Init(pdev);       USBH_MSC_BOTXferParam.MSCState = USBH_MSC_BOT_BULK;         break;   case USBH_MSC_BOT_BULK:     USBH_BulkReceiveData (pdev, Buffer, 512, MSC_Machine.hc_num_in);     USBH_MSC_BOTXferParam.MSCState = USBH_MSC_BOT_PAUSE3;          break;   case USBH_MSC_BOT_PAUSE3:       if(HCD_GetURB_State(pdev , MSC_Machine.hc_num_in) == URB_DONE)     {         // you stuff           pphost->usr_cb->UserApplication(Buffer);         USBH_MSC_BOTXferParam.MSCState = USBH_MSC_BOT_FINISH;     }       break;   case USBH_MSC_BOT_FINISH:     break; //**************************************************************     case USBH_MSC_CTRL_ERROR_STATE:       /* Issue Clearfeature request */       status = USBH_ClrFeature(pdev,                                phost,                                0x00,                                pphost->Control.hc_num_out);       if(status == USBH_OK )       {         /* If GetMaxLun Request not support, assume Single LUN configuration */         MSC_Machine.maxLun = 0;                    USBH_MSC_BOTXferParam.MSCState = USBH_MSC_BOTXferParam.MSCStateBkp;            }       break;              case USBH_MSC_BOT_USB_TRANSFERS:       /* Process the BOT state machine */       USBH_MSC_HandleBOTXfer(pdev , phost);       break;          case USBH_MSC_DEFAULT_APPLI_STATE:       /* Process Application callback for MSC */       appliStatus = 0;       if(appliStatus == 0)       {         USBH_MSC_BOTXferParam.MSCState = USBH_MSC_DEFAULT_APPLI_STATE;       }       else if (appliStatus == 1)       {         /* De-init requested from application layer */         status =  USBH_APPLY_DEINIT;       }       break;            case USBH_MSC_UNRECOVERED_STATE:              status = USBH_UNRECOVERED_ERROR;              break;            default:       break;            }   }    return status; }

[kroesswang_thomas]

Posted on October 23, 2012 at 16:28

Thanks for the quick answer!

I also used USBH_MSC_Handle to build my Statemachine. What I removed was USBH_MSC_Init(pdev), because as far as I know these function is only for storage devices and I don't need those. My Handle function looks like this: The device sends a response to the SCIP2.0 message. But I never reach case 2 because after the USBH_BulkReceiveData()-function the STM32 gets into an interrupt loop. static USBH_Status USBH_MSC_Handle(USB_OTG_CORE_HANDLE *pdev ,                                    void   *phost) {   USBH_HOST *pphost = phost;        USBH_Status status = USBH_BUSY;   uint8_t mscStatus = USBH_MSC_BUSY;   uint8_t appliStatus = 0;     uint8_t scip20 [8] = {'S','C','I','P','2','.','0',0x0A};   uint8_t scip_BM [3] = {'B','M',0x0A};   uint8_t scip_QT [3] = {'Q','T',0x0A};     static uint8_t answer [40];     static uint8_t urb_status;               if(HCD_IsDeviceConnected(pdev))   {        switch(cdc_state)     {     case USBH_MSC_BOT_INIT_STATE:             urb_status = HCD_GetURB_State(pdev , MSC_Machine.hc_num_out);             if(urb_status != URB_NOTREADY)             {       USBH_BulkSendData (pdev,                                                 &scip20[0],                                                 7 ,                                                 MSC_Machine.hc_num_out);             }             cdc_state = 1;                                          //USB_OTG_BSP_mDelay(100);               break;                  case 1:             urb_status = HCD_GetURB_State(pdev , MSC_Machine.hc_num_out);             if(urb_status == URB_DONE)             {                 USBH_BulkReceiveData (pdev,                             answer,                     USBH_MSC_MPS_SIZE ,                     MSC_Machine.hc_num_in);                                  cdc_state = 2;                 //USB_OTG_BSP_mDelay(100);             }             break;                          case 2:             if(HCD_GetURB_State(pdev , MSC_Machine.hc_num_in) == URB_DONE)             {                 USBH_BulkSendData (pdev,                                                 &scip_QT[0],                                                 3 ,                                                 MSC_Machine.hc_num_out);                 cdc_state = 3;             }                          break;        default:       break;            }   }    return status; }

[dmakhrov9]

Posted on October 23, 2012 at 17:32

I believed I understood C-language before I looked at ST's USB host stack. To me, it is a switch-case-function-pointer massacre 🙂