STM32 USB转串口分析

芯片：STM32F407VE

编译器：KEIL5

作者：SY

日期：2017-9-18 09:56:00

概述

使用 STM32_USB-Host-Device_Lib_V2.2.0 usb 库，将 stm32 作为 usb 设备，实现 usb 转串口的功能。

移植

按照例程添加相关文件后测试，主机端使用 Windows7 X64 ，可以正常识别 usb 设备，Windows 安装驱动后提示：驱动不能正常工作 。

原因

可能是需要主机端安装 USB 转串口驱动。

解决

网上搜索后，安装 stmcdc.ini

;------------------------------------------------------------------------------; STMicroelectronics Comunication Device Class driver (CDC) INF FILE; (C)2010 Copyright STMicroelectronics;------------------------------------------------------------------------------[Version]Signature="$Windows NT$"Class=PortsClassGuid={
  4D36E978-E325-11CE-BFC1-08002BE10318}Provider=%PRVDR%CatalogFile=stmcdc.catDriverVer=04/25/2010,1.3.1[SourceDisksNames]1=%DriversDisk%,,,[SourceDisksFiles][Manufacturer]%MFGNAME%=DeviceList,NT,NTamd64[DestinationDirs]DefaultDestDir = 12;------------------------------------------------------------------------------;            VID/PID Settings;------------------------------------------------------------------------------[DeviceList.NT]%DESCRIPTION%=DriverInstall,USB\VID_0483&PID_5740[DeviceList.NTamd64]%DESCRIPTION%=DriverInstall,USB\VID_0483&PID_5740[DriverInstall.NT]Include=mdmcpq.infCopyFiles=FakeModemCopyFileSectionAddReg=DriverInstall.NT.AddReg[DriverInstall.NT.AddReg]HKR,,DevLoader,,*ntkernHKR,,NTMPDriver,,usbser.sysHKR,,EnumPropPages32,,"MsPorts.dll,SerialPortPropPageProvider"[DriverInstall.NT.Services]AddService=usbser, 0x00000002, DriverServiceInst[DriverServiceInst]DisplayName=%SERVICE%ServiceType = 1 ; SERVICE_KERNEL_DRIVERStartType = 3 ; SERVICE_DEMAND_STARTErrorControl = 1 ; SERVICE_ERROR_NORMALServiceBinary= %12%\usbser.sysLoadOrderGroup = Base;------------------------------------------------------------------------------;              String Definitions;------------------------------------------------------------------------------[Strings]PRVDR = "STMicroelectronics"MFGNAME = "STMicroelectronics."DESCRIPTION = "STMicroelectronics Virtual COM Port"SERVICE = "STM Virtual COM Port"DriversDisk = "STM Drivers Disk"

测试驱动还是不能正常工作

网上搜索发现有驱动安装包的形式：VCP_V1.4.0_Setup.exe ，遂安装，发现还是不能正常工作。

原因

怀疑可能是从机没有移植好，采用 STM32CubeMX 软件自动生成一份下位机程序，测试下来还是和以前移植的程序现象一样

解决

网上搜索原因：，原来是 malloc 内存分配失败，扩大堆内存后，终于驱动安装成功了！

原因

既然 STM32CubeMX 可以成功，应该问题就是出在初始化阶段，仿真仔细排查：

uint8_t  usbd_cdc_Init (void  *pdev,                                uint8_t cfgidx){  uint8_t *pbuf;  /* Open EP IN */  DCD_EP_Open(pdev,              CDC_IN_EP,              CDC_DATA_IN_PACKET_SIZE,              USB_OTG_EP_BULK);}

隐约感觉 CDC_DATA_IN_PACKET_SIZE 可能会有问题，查看来源：

#define CDC_DATA_IN_PACKET_SIZE                CDC_DATA_MAX_PACKET_SIZE#define CDC_DATA_MAX_PACKET_SIZE                512  /* Endpoint IN & OUT Packet size */

问题应该出在这里了，我的 usb 使用的是 usb-hs 高速接口，但是物理层仍然使用内部的 phy ，这样使用起来简单，但是最大速度只能达到全速的速度12Mbps ，而全速设备的最大包大小为 64 字节。修改后，测试终于成功了。而且不需要安装任何第三方驱动！

移植过程中最终要的文件：usbd_cdc_vcp.c

/**  ******************************************************************************  * @file    usbd_cdc_vcp.c  * @author  MCD Application Team  * @version V1.2.0  * @date    09-November-2015  * @brief   Generic media access Layer.  ******************************************************************************  * @attention  *  * 
    
     © COPYRIGHT 2015 STMicroelectronics
    
  *  * Licensed under MCD-ST Liberty SW License Agreement V2, (the "License");  * You may not use this file except in compliance with the License.  * You may obtain a copy of the License at:  *  *        http://www.st.com/software_license_agreement_liberty_v2  *  * Unless required by applicable law or agreed to in writing, software   * distributed under the License is distributed on an "AS IS" BASIS,   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.  * See the License for the specific language governing permissions and  * limitations under the License.  *  ******************************************************************************  */ #ifdef USB_OTG_HS_INTERNAL_DMA_ENABLED #pragma     data_alignment = 4 #endif /* USB_OTG_HS_INTERNAL_DMA_ENABLED *//* Includes ------------------------------------------------------------------*/#include "usbd_cdc_vcp.h"#include "stm32f4xx.h"/* Private typedef -----------------------------------------------------------*//* Private define ------------------------------------------------------------*//* Private macro -------------------------------------------------------------*//* Private variables ---------------------------------------------------------*/LINE_CODING linecoding =  {    115200, /* baud rate*/    0x00,   /* stop bits-1*/    0x00,   /* parity - none*/    0x08    /* nb. of bits 8*/  };USART_InitTypeDef USART_InitStructure;/* These are external variables imported from CDC core to be used for IN    transfer management. */extern uint8_t  APP_Rx_Buffer []; /* Write CDC received data in this buffer.                                     These data will be sent over USB IN endpoint                                     in the CDC core functions. */extern uint32_t APP_Rx_ptr_in;    /* Increment this pointer or roll it back to                                     start address when writing received data                                     in the buffer APP_Rx_Buffer. *//* Private function prototypes -----------------------------------------------*/static uint16_t VCP_Init     (void);static uint16_t VCP_DeInit   (void);static uint16_t VCP_Ctrl     (uint32_t Cmd, uint8_t* Buf, uint32_t Len);static uint16_t VCP_DataTx   (void);static uint16_t VCP_DataRx   (uint8_t* Buf, uint32_t Len);static uint16_t VCP_COMConfig(uint8_t Conf);CDC_IF_Prop_TypeDef VCP_fops = {  VCP_Init,  VCP_DeInit,  VCP_Ctrl,  VCP_DataTx,  VCP_DataRx};static uint8_t g_RxByte;/* Private functions ---------------------------------------------------------*//**  * @brief  VCP_Init  *         Initializes the Media on the STM32  * @param  None  * @retval Result of the operation (USBD_OK in all cases)  */static uint16_t VCP_Init(void){   return USBD_OK;}/**  * @brief  VCP_DeInit  *         DeInitializes the Media on the STM32  * @param  None  * @retval Result of the operation (USBD_OK in all cases)  */static uint16_t VCP_DeInit(void){  return USBD_OK;}/**  * @brief  VCP_Ctrl  *         Manage the CDC class requests  * @param  Cmd: Command code              * @param  Buf: Buffer containing command data (request parameters)  * @param  Len: Number of data to be sent (in bytes)  * @retval Result of the operation (USBD_OK in all cases)  */static uint16_t VCP_Ctrl (uint32_t Cmd, uint8_t* Buf, uint32_t Len){   switch (Cmd)  {  case SEND_ENCAPSULATED_COMMAND:    /* Not  needed for this driver */    break;  case GET_ENCAPSULATED_RESPONSE:    /* Not  needed for this driver */    break;  case SET_COMM_FEATURE:    /* Not  needed for this driver */    break;  case GET_COMM_FEATURE:    /* Not  needed for this driver */    break;  case CLEAR_COMM_FEATURE:    /* Not  needed for this driver */    break;  case SET_LINE_CODING:    linecoding.bitrate = (uint32_t)(Buf[0] | (Buf[1] << 8) | (Buf[2] << 16) | (Buf[3] << 24));    linecoding.format = Buf[4];    linecoding.paritytype = Buf[5];    linecoding.datatype = Buf[6];    /* Set the new configuration */    VCP_COMConfig(OTHER_CONFIG);    break;  case GET_LINE_CODING:    Buf[0] = (uint8_t)(linecoding.bitrate);    Buf[1] = (uint8_t)(linecoding.bitrate >> 8);    Buf[2] = (uint8_t)(linecoding.bitrate >> 16);    Buf[3] = (uint8_t)(linecoding.bitrate >> 24);    Buf[4] = linecoding.format;    Buf[5] = linecoding.paritytype;    Buf[6] = linecoding.datatype;     break;  case SET_CONTROL_LINE_STATE:    /* Not  needed for this driver */    break;  case SEND_BREAK:    /* Not  needed for this driver */    break;      default:    break;  }  return USBD_OK;}/**  * @brief  VCP_DataTx  *         CDC received data to be send over USB IN endpoint are managed in   *         this function.  * @param  Buf: Buffer of data to be sent  * @param  Len: Number of data to be sent (in bytes)  * @retval Result of the operation: USBD_OK if all operations are OK else VCP_FAIL  */static uint16_t VCP_DataTx (void){  if (linecoding.datatype == 7)  {    APP_Rx_Buffer[APP_Rx_ptr_in] = g_RxByte & 0x7F;  }  else if (linecoding.datatype == 8)  {    APP_Rx_Buffer[APP_Rx_ptr_in] = g_RxByte;  }  APP_Rx_ptr_in++;  /* To avoid buffer overflow */  if(APP_Rx_ptr_in == APP_RX_DATA_SIZE)  {    APP_Rx_ptr_in = 0;  }    return USBD_OK;}/**  * @brief  VCP_DataRx  *         Data received over USB OUT endpoint are sent over CDC interface   *         through this function.  *             *         @note  *         This function will block any OUT packet reception on USB endpoint   *         until exiting this function. If you exit this function before transfer  *         is complete on CDC interface (ie. using DMA controller) it will result   *         in receiving more data while previous ones are still not sent.  *                   * @param  Buf: Buffer of data received  * @param  Len: Number of data received (in bytes)  * @retval Result of the operation: USBD_OK if all operations are OK else VCP_FAIL  */static uint16_t VCP_DataRx (uint8_t* Buf, uint32_t Len){  for (uint32_t i=0; i

实现的功能是做一个loopback 测试，只要收到数据立刻发出去。

测试

实际测试下来，波特率设置为 256000bps ，按照 1ms 定时发送，发送：13227744byte 接收：13227744byte 没有丢失数据。

usb 转串口总是被大家认为是不稳定，原因就是在 usb 线拔掉后，串口也随之消失。原来操作系统为串口分配的内存等资源也没有被正确的释放，再将串口线插回去时，会出现打开串口失败！

下面提出操作 USB 转串口的正确方式：

插上 usb 线，打开主机端串口；使用完毕后关闭串口，拔掉 usb 线

插上 usb 线，打开主机端串口；拔掉 usb 线，关闭串口；插上 usb 线，打开串口

失败的方式：

插上 usb 线，打开主机端串口；拔掉 usb 线，插上 usb 线；主机发送数据失败

插上 usb 线，打开主机端串口；拔掉 usb 线，插上 usb 线；关闭串口，打开串口；主机发送数据失败

转载地址：http://hnzii.baihongyu.com/

你可能感兴趣的文章