[原创] stm32105写U盘问题

我使用STM32F105RB程序作了一段写U盘扇区的代码

U8 MassStorageDevSectWrite(U32 LBAddr,U16 Len,U8 *PtrBuf)
{
    U32 *tmp;
    U32 Tag=0x0000000c,TotalByteNum_32,MassStorageDevSectReadTryCnt;
    U16 TotalByteNum_16;

    CBW.dCBWSignature=dCBWSignatureValue;
    CBW.dCBWTag=Tag;         //tag value, to be returned unchanged in CSW

 TotalByteNum_32=Len*UsbDevHandler.BPB_BytesPerSect;
    TotalByteNum_16=Len*UsbDevHandler.BPB_BytesPerSect;
    CBW.dCBWDataTransferLength=TotalByteNum_32;
                    //number of bytes that the host expects to receive from the device
    CBW.bmCBWFlags=0x00;     //bit 7: 1: DataIn from device
                    //bit 7: 0: DataOut to device
    CBW.bCBWLUN=0x00;//UsbDevHandler.LunToBeUsed;
                             //the device Logic Unit Number, to which the CBW is sent to
    CBW.bCBWCBLength=12;     //valid data in the CBW union CmdBlockByteArray, only could be
                    //from 0x01 to 0x10
    //clear cmd array
    tmp=(U32 *)CBW.CmdBlockByteArray;
    *tmp++=0;*tmp++=0;*tmp++=0;*tmp++=0;
    //fill the cmd array
    CBW.CmdBlockByteArray[0]=0x2A;
    CBW.CmdBlockByteArray[1]=0x00;
    CBW.CmdBlockByteArray[2]=(U8)((LBAddr>>24)&0xff);
    CBW.CmdBlockByteArray[3]=(U8)((LBAddr>>16)&0xff);
    CBW.CmdBlockByteArray[4]=(U8)((LBAddr>>8)&0xff);
    CBW.CmdBlockByteArray[5]=(U8)(LBAddr&0xff);
    CBW.CmdBlockByteArray[6]=0x00;
    CBW.CmdBlockByteArray[7]=(U8)((Len>>8)&0xff);
    CBW.CmdBlockByteArray[8]=(U8)(Len&0xff);
    CBW.CmdBlockByteArray[9]=0x00;
 PrepareCBWTxBuf();
    if(epBulkOutTransfer(CBWTxBuf,31)) return(1);
    MsDelay(150);
 MassStorageDevSectReadTryCnt=0;
    while(1)
    {
     if(!epBulkOutTransfer(PtrBuf,TotalByteNum_16))
     {
      MsDelay(300);
         break;
     } else
     {
         MassStorageDevSectReadTryCnt++;
         if (MassStorageDevSectReadTryCnt>5) return(1);
     };
    };
 MsDelay(100);
  if(epBulkInTransfer(CSWRxBuf,13)) return(3);
    InterpretCSWRxBuf();     //get back CSW
    if(AuditCSWReturned(&CSW,Tag)) return(4);

    return(0);

}

程序单步调试的时候运行到这个红色的地方，老是取不回CSW的数据，不知道是为什么忘高手指点。

我的程序可以读取U盘文件中的数据，但是写U盘在这个地方总有问题。

U16 GetFreeCusterNum_32(void)
{
 
 U32  clusterNum;          
 U32  s = FatStarts;   //s 指向FAT16表头
 U16   i;

 clusterNum = 0;

 while (s < FatStarts + BPB_FATSz32)
 {
  if (MassStorageDevSectRead(0,1,UDiskBuf))             //逐个扇区地读取FAT信息
   return 0x0;
  for (i=0; i<512; i=i+4)
  {
   if (DW_BUF(UDiskBuf,i) == 0)
   {
    UDiskBuf = 0xff;
    UDiskBuf[i+1] = 0xff;
    UDiskBuf[i+2] = 0xff;
    UDiskBuf[i+3] = 0xff;
    if(MassStorageDevSectWrite(s,1,UDiskBuf))
    {
     return 0x0;
    }
       return clusterNum;
   }
   clusterNum++;
  }
  s = s + 1;
 }
 return 0x0;
}