Qt下libusb-win32的使用(二)批量读写操作

一、概述

学习libusb-win32的使用。使用批量传输方式与USB开发板进行数据读、写操作。上位机使用Qt做界面， 使用USB开发板的端点2作为批量传输端点。

二、实现

代码比较简单，直接给出，如下：

 #include "testlibusb.h"

 //for Tiny6410
 //#define MY_VID 0x5345
 //#define MY_PID 0x1234

 //for 51 USB Board
 #define MY_VID 0x8888
 #define MY_PID 0x0001

 // Device configuration and interface id.
 #define MY_CONFIG 1
 #define MY_INTF 0

 // Device endpoint 2
 #define EP_IN 0x82
 #define EP_OUT 0x02

 // Device of bytes to transfer.
 #define BUF_SIZE 64

 //#define DEBUG_GUI

 USB::USB()
 {
 #ifndef DEBUG_GUI

     usb_init(); /* initialize the library */
     //usb_set_debug(255);
     usb_find_busses(); /* find all busses */
     usb_find_devices(); /* find all connected devices */

     if (!(udev = open_dev())) {
         qDebug("error opening device: %s", usb_strerror());
         exit();
     } else
         qDebug("open success: device %04X:%04X opened", MY_VID, MY_PID);

     printf_device_descriptor(&dev->descriptor);
     my_init_usbdev();
 #endif

     textEdit = new QTextEdit(this);
     textEdit->setGeometry(,,,);

     sendButton = new QPushButton(this);
     sendButton->setText("send");
     sendButton->setGeometry(,,,);
     connect(sendButton,SIGNAL(clicked()),this,SLOT(send_slot()));

     readButton = new QPushButton(this);
     readButton->setText("read");
     readButton->setGeometry(,,,);
     connect(readButton,SIGNAL(clicked()),this,SLOT(read_slot()));

     recvLabel = new QLabel(this);
     recvLabel->setText("recv data:");
     recvLabel->setGeometry(,,,);

     //my_usb_get_device_list();
     resize(, );
 }

 //关闭程序时被调用
 USB::~USB()
 {
 #ifndef DEBUG_GUI
     qDebug("close usb device.");
     usb_close(udev);
 #endif
 }

 //打开指定VID、PID的USB设备
 usb_dev_handle *USB::open_dev(void)
 {
     struct usb_bus *bus;

     for(bus = usb_get_busses(); bus; bus = bus->next) {
         for(dev = bus->devices; dev; dev = dev->next) {
             if((dev->descriptor.idVendor == MY_VID) && (dev->descriptor.idProduct == MY_PID)) {
                     return usb_open(dev);
             }
         }
     }
     return ;
 }

 //打印USB设备描述符
 void USB::printf_device_descriptor(usb_device_descriptor *desc)
 {
         qDebug("bLength:             %u",     desc->bLength);
         qDebug("bDescriptorType:     %02Xh",  desc->bDescriptorType);
         qDebug("bcdUSB:              %04Xh",  desc->bcdUSB);
         qDebug("bDeviceClass:        %02Xh",  desc->bDeviceClass);
         qDebug("bDeviceSubClass:     %02Xh",  desc->bDeviceSubClass);
         qDebug("bDeviceProtocol:     %02Xh",  desc->bDeviceProtocol);
         qDebug("bMaxPacketSize0:     %02Xh",  desc->bMaxPacketSize0);
         qDebug("idVendor:            %04Xh",  desc->idVendor);
         qDebug("idProduct:           %04Xh",  desc->idProduct);
         qDebug("bcdDevice:           %04Xh",  desc->bcdDevice);
         qDebug("iManufacturer:       %u",     desc->iManufacturer);
         qDebug("iProduct:            %u",     desc->iProduct);
         qDebug("iSerialNumber:       %u",     desc->iSerialNumber);
         qDebug("bNumConfigurations:  %u",     desc->bNumConfigurations);
 }

 //指定USB设备的配置和接口
 void USB::my_init_usbdev()
 {
     //libusb规定下面这两个函数必须要被调用
     if (usb_set_configuration(udev, MY_CONFIG) < ) {
         qDebug("error setting config #%d: %s", MY_CONFIG, usb_strerror());
         exit();
     }
     if (usb_claim_interface(udev, MY_INTF) < ) {
         qDebug("error claiming interface #%d:\n%s", MY_INTF, usb_strerror());
         exit();
     }
 }

 //发送按钮响应函数
 void USB::send_slot()
 {
     int ret, num;
     QString s = textEdit->toPlainText();
     QByteArray a = s.toLatin1();
     char *tmp = a.data();

     num = s.length();
     //qDebug()<<"text: "<<tmp<<"length: "<<num;
     //批量写(同步)
     ret = usb_bulk_write(udev, EP_OUT, tmp, num, );
     if (ret < ) {
             qDebug("error writing: %s", usb_strerror());
             exit();
     }
 }

 //读按钮响应函数
 void USB::read_slot()
 {
     int ret;
     char readdata[BUF_SIZE];

     //批量读(同步)
     ret = usb_bulk_read(udev, EP_IN, readdata, sizeof(readdata), );
     if (ret < ) {
             qDebug("error reading:%s", usb_strerror());
             exit();
     }
     readdata[ret] = '\0';
     //将接收到的数据显示在Label上
     recvLabel->setText("recv: " + QLatin1String(readdata));
 }

三、结果

运行上位机程序，在编辑框输入一些字符(数字)，然后点击“send”按钮将数据发送给USB设备，点击“read”按钮将USB设备接收到的数据读回到上位机并显示在界面上，效果如下：