Unable to claim USB interface with C + libusb on Mac OS X
我有一個使用PIC32單片機構建的復合USB + CDC設備，我正在嘗試連接到該設備並從Mac將一些數據發送到CDC數據接口端點。
我知道電路可以工作100％，因為該設備同時注冊為HID操縱桿，並且我可以使用/dev/tty.usbmodemfa132上的Zoc終端連接到該設備。我可以使用Zoc發送命令，並通過閃爍電路上的一些LED來查看我的MCU對這些命令的響應。
我在Mac OS X Mavericks上運行此程序，但是在幾個星期前我在Mountain Lion上放棄的類似示例也遇到了同樣的問題。
我的代碼如下所示：
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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 ) ; } |
我收到以下錯誤輸出：
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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 |
有什么方法可以釋放其他過程中的USB設備，釋放它以便我可以聲明它嗎？
有沒有其他方法可以連接到/dev/tty.usbmodemfa132以向USB設備上的CDC接口發送和接收數據？
也許是libusb的替代品？
那就對了。盡管libusb在Linux中似乎是功能強大的，但是您不能使用它來連接Mac OS X上的USB CDC接口，因為AppleUSBCDCACM驅動程序已經聲明了該接口。
您應該做的是使用人們連接到串行端口的標准方法。這將更容易，因為您不必擔心端點和批量傳輸等。這是我為基於CDC的產品之一編寫的一些跨平台C代碼示例，該產品連接到COM端口以讀取和寫入一些數據(源)。它使用標准功能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 ; } |
如果要使用Apple FTDI串行驅動程序也可以識別的某些USB設備，則可以先卸載該驅動程序：
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sudo kextunload
-b com.
apple.
driver.
AppleUSBFTDI
|
之后，您可以正常通過libusb使用它。
對於被識別為串行設備的其他設備，您可能需要卸載其他驅動程序。
問題似乎是由於使用相同庫的不同驅動程序之間存在沖突，在我的情況下，它們與先前的三星設備安裝有關。我已經解決了這種方式：
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kextstat
| grep
-v apple
|
獲得這樣的回報：
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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 |