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(1);
    } 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(50,20,230,40);

    sendButton = new QPushButton(this);
    sendButton->setText("send");
    sendButton->setGeometry(130,80,60,40);
    connect(sendButton,SIGNAL(clicked()),this,SLOT(send_slot()));

    readButton = new QPushButton(this);
    readButton->setText("read");
    readButton->setGeometry(130,140,60,40);
    connect(readButton,SIGNAL(clicked()),this,SLOT(read_slot()));

    recvLabel = new QLabel(this);
    recvLabel->setText("recv data:");
    recvLabel->setGeometry(20,180,280,40);

    //my_usb_get_device_list();
    resize(320, 240);
}

//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 0;
}

//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) < 0) {
        qDebug("error setting config #%d: %s", MY_CONFIG, usb_strerror());
        exit(1);
    }
    if (usb_claim_interface(udev, MY_INTF) < 0) {
        qDebug("error claiming interface #%d:
%s", MY_INTF, usb_strerror());
        exit(1);
    }
}

//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, 5000);
    if (ret < 0) {
            qDebug("error writing: %s", usb_strerror());
            exit(1);
    }
}

//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), 5000);
    if (ret < 0) {
            qDebug("error reading:%s", usb_strerror());
            exit(1);
    }
    readdata[ret] = '';
    //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：