在Mac OS X上無法使用C + libusb宣告USB介面
阿新 • • 發佈：2021-11-27
Unable to claim USB interface with C + libusb on Mac OS X
我有一個使用PIC32微控制器構建的複合USB + CDC裝置，我正在嘗試連線到該裝置並從Mac將一些資料傳送到CDC資料介面端點。
我知道電路可以工作100％，因為該裝置同時註冊為HID操縱桿，並且我可以使用/dev/tty.usbmodemfa132上的Zoc終端連線到該裝置。我可以使用Zoc傳送命令，並通過閃爍電路上的一些LED來檢視我的MCU對這些命令的響應。
我在Mac OS X Mavericks上執行此程式，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。
我的程式碼如下所示：
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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 |
有什麼方法可以釋放其他過程中的USB裝置，釋放它以便我可以宣告它嗎？
有沒有其他方法可以連線到/dev/tty.usbmodemfa132以向USB裝置上的CDC介面傳送和接收資料？
也許是libusb的替代品？
相關討論那就對了。儘管libusb在Linux中似乎是功能強大的，但是您不能使用它來連線Mac OS X上的USB CDC介面，因為AppleUSBCDCACM驅動程式已經聲明瞭該介面。
您應該做的是使用人們連線到串列埠的標準方法。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臺C程式碼示例，該產品連線到COM埠以讀取和寫入一些資料(源)。它使用標準功能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序列驅動程式也可以識別的某些USB裝置，則可以先解除安裝該驅動程式：
| 1 | sudo kextunload -b com.apple.driver.AppleUSBFTDI |
之後，您可以正常通過libusb使用它。
對於被識別為序列裝置的其他裝置，您可能需要解除安裝其他驅動程式。
問題似乎是由於使用相同庫的不同驅動程式之間存在衝突，在我的情況下，它們與先前的三星裝置安裝有關。我已經解決了這種方式：
| 1 | 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> |
然後：
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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 |