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：

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162

// 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：

1
2
3
4
5
6
7

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。

// 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;
}

快乐的GTD吧

Everyone, Have a good day.

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

公告