Question

我可以成功地将数据发送到USB设备，但每次设备的响应都会失败。我确信端点是正确的，因为使用windows中的hid api与相同设备成功通信。

这是我的代码：

struct libusb_context*  hContxt;

libusb_init(&hContxt);

libusb_set_debug(hContxt, LIBUSB_LOG_LEVEL_DEBUG);

libusb_device_handle*   hUsbHandle = libusb_open_device_with_vid_pid(hContxt, 0x0483, 0x3021);;

if (NULL == hUsbHandle)
{
    printf("open failed!\n");
    return 0;
}

libusb_claim_interface(hUsbHandle, 0);

int _nMaxPackSize = libusb_get_max_packet_size(libusb_get_device(hUsbHandle), 0x01);

unsigned char _szCmd[1024] = "12355666";
int _nSendSuccessLen = 0;

int _nRet = libusb_interrupt_transfer(hUsbHandle, 0x01,\
    const_cast<unsigned char*>(&_szCmd[0]), _nMaxPackSize, &_nSendSuccessLen, 200);

unsigned char recv[1024];
int     recvExpectLen = 0;
int     recvAcutalLen = 0;

_nMaxPackSize = libusb_get_max_packet_size(libusb_get_device(hUsbHandle), 0x81);

while(1)
{
    memset(recv, 0x00, sizeof recv);

    _nRet = libusb_interrupt_transfer(hUsbHandle, 0x81,\
        const_cast<unsigned char*>(recv), _nMaxPackSize, &recvAcutalLen, 1000);//block in libusb_handle_events_timeout_completed.

    if (_nRet == LIBUSB_SUCCESS)
    {
        printf("recv Len: %d\n", recvAcutalLen);
    }

    Sleep(1000);
}

我是否需要设置libusb的其他API？

libusb的调试信息如下：

[ 0.811201] [00000820] libusb: debug [hid_submit_bulk_transfer] matched endpoint
 81 with interface 0
[ 0.811201] [00000820] libusb: debug [hid_submit_bulk_transfer] reading 65 bytes
 (report ID: 0x00)
[ 0.826801] [00000820] libusb: debug [libusb_get_next_timeout] next timeout in 0
.982700s
[ 0.826801] [00000820] libusb: debug [libusb_handle_events_timeout_completed] do
ing our own event handling
[ 0.842401] [00000820] libusb: debug [handle_events] poll fds modified, reallocating
[ 0.842401] [00000820] libusb: debug [handle_events] poll() 2 fds with timeout i
n 983ms
[ 1.840803] [00000820] libusb: debug [handle_events] poll() returned 0
[ 1.840803] [00000820] libusb: debug [libusb_cancel_transfer] transfer 00474628
[ 1.872003] [00000820] libusb: debug [hid_abort_transfers] will use interface 0<br/>
[ 1.887603] [00000820] libusb: warning [hid_abort_transfers] cancel failed: [6]
句柄无效。<br/>
[ 1.918803] [00000820] libusb: debug [libusb_cancel_transfer] cancel transfer failed error -5
[ 1.918803] [00000820] libusb: warning [handle_timeout] async cancel failed -5 errno=0
[ 1.918803] [00000820] libusb: debug [libusb_get_next_timeout] no URB with timeo
ut or all handled by OS; no timeout!
[ 1.918803] [00000820] libusb: debug [libusb_handle_events_timeout_completed] do
ing our own event handling
[ 1.934403] [00000820] libusb: debug [handle_events] poll() 2 fds with timeout i
n 60000ms

为什么libusb Library在接口libusb_interrupt_transfer中阻塞？

0 个答案: