[英]How do I receive HID reports using libusb-1.0?
I have a USB HID scale that I need to fetch the weighing reports from. 我有一个USB HID刻度,我需要从中获取称重报告。 I am able to do this on Linux by reading 7 bytes at a time from
/dev/hidraw#
, but I would like to get the same information using libusb-1.0. 我可以通过从
/dev/hidraw#
一次读取7个字节来在Linux上执行此操作,但我想使用libusb-1.0获取相同的信息。
Even when I do get some non-null bytes, I get error -9: LIBUSB_ERROR_PIPE
即使我得到一些非空字节,我得到错误-9:
LIBUSB_ERROR_PIPE
I am attempting to use a control transfer like so: 我试图像这样使用控制转移:
#define WEIGH_REPORT_SIZE 7
/*
* Open a handle to the found scale
*/
libusb_open(dev, &handle);
#ifdef __linux__
libusb_detach_kernel_driver(handle, 0);
#endif
libusb_claim_interface(handle, 0);
/*
* Try to transfer data about status
*
*/
unsigned char data[WEIGH_REPORT_SIZE];
unsigned int len = libusb_control_transfer(
handle,
LIBUSB_ENDPOINT_IN | LIBUSB_REQUEST_TYPE_CLASS |
LIBUSB_RECIPIENT_INTERFACE,
HID_REPORT_GET,
//wValue => hid report, no report ID
0x0100,
0x00, //windex => interface 0
data,
WEIGH_REPORT_SIZE, //wLength
10000 //timeout => 10 sec
);
int i;
printf("Got %d bytes from control transfer:\n", len);
for(i = 0; i < WEIGH_REPORT_SIZE; i++) {
printf("%x\n", data[i]);
}
An example to read from a USB HID card reader using libusb-win - 使用libusb-win从USB HID读卡器读取的示例 -
http://rowsandcolumns.blogspot.com/2011/02/read-from-magtek-card-swipe-reader-in.html http://rowsandcolumns.blogspot.com/2011/02/read-from-magtek-card-swipe-reader-in.html
HID uses Interrupt Transfer AFAIK. HID使用中断传输AFAIK。 You need to rewrite your code to use these.
您需要重写代码才能使用它们。 And have a look at thouse descriptors - they tell you which interface to use.
并查看thouse描述符 - 它们告诉您使用哪个接口。
That said I think its much easier to use /dev/hdiraw# then libusb in this case. 这就是说我认为在这种情况下使用/ dev / hdiraw#然后libusb更容易。
Try to use another value for wValue
( 0x0300
, for example). 尝试为
wValue
使用另一个值(例如0x0300
)。
Also check bmRequestType
and bRequest
parameters: bmRequestType
must be equal to 0xA1
, bRequest
— 0x01
. 还要检查
bmRequestType
和bRequest
参数: bmRequestType
必须等于0xA1
, bRequest
- 0x01
。
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