在Mac OS X上无法使用C + libusb声明USB接口

Unable to claim USB interface with C + libusb on Mac OS X

 

 

我有一个使用PIC32单片机构建的复合USB + CDC设备,我正在尝试连接到该设备并从Mac将一些数据发送到CDC数据接口端点。

我知道电路可以工作100%,因为该设备同时注册为HID操纵杆,并且我可以使用/dev/tty.usbmodemfa132上的Zoc终端连接到该设备。我可以使用Zoc发送命令,并通过闪烁电路上的一些LED来查看我的MCU对这些命令的响应。

我在Mac OS X Mavericks上运行此程序,但是在几个星期前我在Mountain Lion上放弃的类似示例也遇到了同样的问题。

我的代码如下所示:

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// Includes -----------------------------------------------------------------------------------------------------------
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <libusb-1.0/libusb.h>
#include <unistd.h>

// Defines ------------------------------------------------------------------------------------------------------------
#define VID 0x04d8
#define PID 0x005e
#define CDC_DATA_INTERFACE_ID 2

// Function Declarations ----------------------------------------------------------------------------------------------
void print_device(libusb_device *device);
void send(libusb_context *usb_context, uint16_t vid, uint16_t pid);

// Function Definitions -----------------------------------------------------------------------------------------------

/**
 * main
 */
int main(int argc, char **argv)
{
    libusb_device **usb_devices = NULL;
    libusb_context *usb_context = NULL;
    ssize_t device_count = 0;
    bool debug_enabled = false;
    int c;

    // Collect command line attributes
    while ( (c = getopt(argc, argv,"d")) != -1) {
        switch (c) {
            case 'd':
                debug_enabled = true;
                break;
        }
    }

    // Initialize USB context
    int result = libusb_init(&usb_context);
    if(result < 0) {
        printf("Unable to initialise libusb!");
        return EXIT_FAILURE;
    }

    // Turn debug mode on/off
    if(debug_enabled) {
        libusb_set_debug(usb_context, 3);
    }

    // Get USB device list
    device_count = libusb_get_device_list(usb_context, &usb_devices);
    if(device_count < 0) {
        puts("Unable to retrieve USB device list!");
    }

    // Iterate and print devices
    puts("VID    PID     Manufacturer Name\
------ ------ -------------------");
    for (int i = 0; i < device_count; i++) {
        print_device(usb_devices[i]);
    }

    // Attempt to send data
    send(usb_context, VID, PID);

    // Cleanup and exit
    libusb_free_device_list(usb_devices, 1);
    libusb_exit(usb_context);
    return EXIT_SUCCESS;
}

/**
 * print_device
 */
void print_device(libusb_device *device)
{
    struct libusb_device_descriptor device_descriptor;
    struct libusb_device_handle *device_handle = NULL;

    // Get USB device descriptor
    int result = libusb_get_device_descriptor(device, &device_descriptor);
    if (result < 0) {
        printf("Failed to get device descriptor!");
    }

    // Only print our devices
    if(VID == device_descriptor.idVendor && PID == device_descriptor.idProduct) {
        // Print VID & PID
        printf("0x%04x 0x%04x", device_descriptor.idVendor, device_descriptor.idProduct);
    } else {
        return;
    }

    // Attempt to open the device
    int open_result = libusb_open(device, &device_handle);
    if (open_result < 0) {
        libusb_close(device_handle);
        return;
    }

    // Print the device manufacturer string
    char manufacturer[256] ="";
    if (device_descriptor.iManufacturer) {
        libusb_get_string_descriptor_ascii(device_handle, device_descriptor.iManufacturer,
            (unsigned char *)manufacturer, sizeof(manufacturer));
        printf(" %s", manufacturer);
    }

    puts("");

    libusb_close(device_handle);
}

/**
 * send
 */
void send(libusb_context *usb_context, uint16_t vid, uint16_t pid)
{
    libusb_device_handle *device_handle;
    device_handle = libusb_open_device_with_vid_pid(usb_context, vid, pid);

    if (device_handle == NULL) {
        puts("Unable to open device by VID & PID!");
        return;
    }
    puts("Device successfully opened");

    unsigned char *data = (unsigned char *)"test";

    if (libusb_kernel_driver_active(device_handle, CDC_DATA_INTERFACE_ID)) {
        puts("Kernel driver active");
        if (libusb_detach_kernel_driver(device_handle, CDC_DATA_INTERFACE_ID)) {
            puts("Kernel driver detached");
        }
    } else {
        puts("Kernel driver doesn't appear to be active");
    }

    int result = libusb_claim_interface(device_handle, CDC_DATA_INTERFACE_ID);
    if (result < 0) {
        puts("Unable to claim interface!");
        libusb_close(device_handle);
        return;
    }
    puts("Interface claimed");

    int written = 0;
    result = libusb_bulk_transfer(device_handle, (3 | LIBUSB_ENDPOINT_OUT), data, 4, &written, 0);
    if (result == 0 && written == 4) {
        puts("Send success");
    } else {
        puts("Send failed!");
    }

    result = libusb_release_interface(device_handle, CDC_DATA_INTERFACE_ID);
    if (result != 0) {
        puts("Unable to release interface!");
    }

    libusb_close(device_handle);
}

我收到以下错误输出:

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libusb: 0.828223 error [darwin_open] USBDeviceOpen: another process has device opened for exclusive access
libusb: 0.828241 info [darwin_open] device open for access
Device successfully opened
Kernel driver doesn't appear to be active
libusb: 0.828641 error [darwin_claim_interface] USBInterfaceOpen: another process has device opened for exclusive access
Unable to claim interface!
libusb: 0.828766 info [event_thread_main] thread exiting

 

 

有什么方法可以释放其他过程中的USB设备,释放它以便我可以声明它吗?

有没有其他方法可以连接到/dev/tty.usbmodemfa132以向USB设备上的CDC接口发送和接收数据?

也许是libusb的替代品?

相关讨论  

 


那就对了。尽管libusb在Linux中似乎是功能强大的,但是您不能使用它来连接Mac OS X上的USB CDC接口,因为AppleUSBCDCACM驱动程序已经声明了该接口。

 

 

您应该做的是使用人们连接到串行端口的标准方法。这将更容易,因为您不必担心端点和批量传输等。这是我为基于CDC的产品之一编写的一些跨平台C代码示例,该产品连接到COM端口以读取和写入一些数据(源)。它使用标准功能open,read和write。

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// Uses POSIX functions to send and receive data from a Maestro.
// NOTE: You must change the 'const char * device' line below.

#include <fcntl.h>
#include <stdio.h>
#include <unistd.h>

#ifdef _WIN32
#define O_NOCTTY 0
#else
#include <termios.h>
#endif

// Gets the position of a Maestro channel.
// See the"Serial Servo Commands" section of the user's guide.
int maestroGetPosition(int fd, unsigned char channel)
{
  unsigned char command[] = {0x90, channel};
  if(write(fd, command, sizeof(command)) == -1)
  {
    perror("error writing");
    return -1;
  }

  unsigned char response[2];
  if(read(fd,response,2) != 2)
  {
    perror("error reading");
    return -1;
  }

  return response[0] + 256*response[1];
}

// Sets the target of a Maestro channel.
// See the"Serial Servo Commands" section of the user's guide.
// The units of 'target' are quarter-microseconds.
int maestroSetTarget(int fd, unsigned char channel, unsigned short target)
{
  unsigned char command[] = {0x84, channel, target & 0x7F, target >> 7 & 0x7F};
  if (write(fd, command, sizeof(command)) == -1)
  {
    perror("error writing");
    return -1;
  }
  return 0;
}

int main()
{
  // Open the Maestro's virtual COM port.
  const char * device ="\\\\\\\\.\\\\USBSER000";  // Windows,"\\\\\\\\.\\\\COM6" also works
  //const char * device ="/dev/ttyACM0";  // Linux
  //const char * device ="/dev/cu.usbmodem00034567"; // Mac OS X
  int fd = open(device, O_RDWR | O_NOCTTY);
  if (fd == -1)
  {
    perror(device);
    return 1;
  }

#ifndef _WIN32
  struct termios options;
  tcgetattr(fd, &options);
  options.c_lflag &= ~(ECHO | ECHONL | ICANON | ISIG | IEXTEN);
  options.c_oflag &= ~(ONLCR | OCRNL);
  tcsetattr(fd, TCSANOW, &options);
#endif

  int position = maestroGetPosition(fd, 0);
  printf("Current position is %d.\
", position);

  int target = (position < 6000) ? 7000 : 5000;
  printf("Setting target to %d (%d us).\
", target, target/4);
  maestroSetTarget(fd, 0, target);

  close(fd);
  return 0;
}
相关讨论  

 


如果要使用Apple FTDI串行驱动程序也可以识别的某些USB设备,则可以先卸载该驱动程序:

1 sudo kextunload -b com.apple.driver.AppleUSBFTDI

之后,您可以正常通过libusb使用它。

对于被识别为串行设备的其他设备,您可能需要卸载其他驱动程序。


问题似乎是由于使用相同库的不同驱动程序之间存在冲突,在我的情况下,它们与先前的三星设备安装有关。我已经解决了这种方式:

1 kextstat | grep -v apple

 

 

获得这样的回报:

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  70    0 0x57574000 0x3000     0x2000     com.devguru.driver.SamsungComposite (1.2.4) <33 4 3>
  72    0 0x57831000 0x7000     0x6000     com.devguru.driver.SamsungACMData (1.2.4) <71 33 5 4 3>
  94    0 0x57674000 0x3000     0x2000     com.devguru.driver.SamsungACMControl (1.2.4) <33 4 3>

然后:

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$ sudo kextunload -b com.devguru.driver.SamsungComposite
$ sudo kextunload -b com.devguru.driver.SamsungACMData
$ sudo kextunload -b com.devguru.driver.SamsungACMControl
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