Linux 想要 libusb 基本示例
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libusb basic example wanted
提问by Vladimir
I'm writing user-space program that is intended to control some device via usb so I decided to use libusb (libusb-1.0) to send control messages to and receive responses from that device.
我正在编写旨在通过 USB 控制某些设备的用户空间程序，因此我决定使用 libusb (libusb-1.0) 向该设备发送控制消息并从该设备接收响应。
But I constantly receive the following bunch of errors from my code (even when it's executed using 'sudo'):
但是我不断从我的代码中收到以下一堆错误（即使它是使用“sudo”执行的）：
USB error: could not set config 0: Device or resource busy
set configuration: failed
Check that you have permissions to write to 007/012 and, if you don't, that you set up hotplug (http://linux-hotplug.sourceforge.net/) correctly.
USB error: could not claim interface 0: Device or resource busy
claim interface: failed
USB error: error submitting URB: No such file or directory
bulk writing: failed
USB error: error submitting URB: No such file or directory
bulk reading: failed
response was:
The code is:
代码是：
usb_dev_handle* find_device ();
int
main (int argc, char *argv[])
{
usb_dev_handle* udev;
int status;
char request[] = "K1"; // 'ping' command used to check communication
char response[256];
udev = find_device ();
// udev is successfully found here
status = usb_set_configuration (udev, 0);
printf ("set configuration: %s\n", status ? "failed" : "passed");
status = usb_claim_interface (udev, 0);
printf ("claim interface: %s\n", status ? "failed" : "passed");
status = usb_bulk_write (udev, 3, request, sizeof (request), 500);
printf ("bulk writing: %s\n", status ? "failed" : "passed");
status = usb_bulk_read (udev, 2, response, sizeof (response), 500);
printf ("bulk reading: %s\n", status ? "failed" : "passed");
printf ("response was: %s\n", response);
usb_close (udev);
return 0;
}
What's wrong with the code? And how it could be fixed?
代码有什么问题？以及如何修复？
OS: Ubuntu 10.10
操作系统： Ubuntu 10.10
回答by AlwaysLearning
Don't you need to open() the device before you set its configuration and claim it?
在设置其配置并声明它之前，您不需要 open() 设备吗？
回答by Samuzzal Choudhury
Answering this question as I had faced this issue on the same OS and was able to solve in the following manner:
回答这个问题，因为我在同一操作系统上遇到过这个问题，并且能够通过以下方式解决：
Download and Compile the latest libusb source code 1.0.8.
下载并编译最新的 libusb 源代码 1.0.8。
Following are some API calls that I used in order to claim USB interface 0:
以下是我用于声明 USB 接口 0 的一些 API 调用：
libusb_init(NULL);
libusb_open_device_with_vid_pid(NULL, vendor_id, product_id);
libusb_detach_kernel_driver(devh, 0);
libusb_claim_interface(devh, 0);
libusb_close(devh);
libusb_exit(NULL);
Description of the variables in the above example:
上例中的变量说明：
static struct libusb_device_handle *devh = NULL;
uint16_t vendor_id;
uint16_t product_id;
To get the vendor ID and product ID, you may run the following commands (Ex. my device info)
要获取供应商 ID 和产品 ID，您可以运行以下命令（例如我的设备信息）
$ lsusb
...
Bus 001 Device 013: ID 0930:6544Toshiba Corp. Kingston DataTraveler 2.0 Stick (2GB)
...
$ lsusb
...
Bus 001 Device 013: ID 0930:6544Toshiba Corp. Kingston DataTraveler 2.0 Stick (2GB)
...
The bold colon delimited string contains vendor and product id respectively.
粗体冒号分隔的字符串分别包含供应商和产品 ID。
How to compile the code:
如何编译代码：
I used the following command to compile my code:
我使用以下命令来编译我的代码：
/bin/bash libtool --silent --tag=CC --mode=link g++ -Wall -Wundef -Wunused -Wshadow -D_DEBUG -I../libusb -g -O2 -o read read.cpp ../libusb/libusb-1.0.la -lusb-1.0 -lrt
/bin/bash libtool --silent --tag=CC --mode=link g++ -Wall -Wundef -Wunused -Wshadow -D_DEBUG -I../libusb -g -O2 -o read read.cpp ../libusb/ libusb-1.0.la -lusb-1.0 -lrt
Copy libtool to the compilation area from the extracted libusb-1.0.8 directory.
从解压出来的 libusb-1.0.8 目录中将 libtool 复制到编译区。
Hope this helps.
希望这可以帮助。
回答by Daniel McGrath
here's a generic example of a libusb program that you can adapt as needed.
这是一个 libusb 程序的通用示例，您可以根据需要对其进行调整。
also see the API, which is great!
另请参阅API，这很棒！
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <libusb.h>
#include <err.h>
#define MFGR_ID 0 // given manufacturer ID
#define DEV_ID 0 // given device ID
/* If device IDs are not known, use libusb_get_device_list() to see a
list of all USB devices connected to the machine. Follow this call with
libusb_free_device_list() to free the allocated device list memory.
*/
int main() {
int init = libusb_init(NULL); // NULL is the default libusb_context
if (init < 0) {
errx(1,”\n\nERROR: Cannot Initialize libusb\n\n”);
}
struct libusb_device_handle *dh = NULL; // The device handle
dh = libusb_open_device_with_vid_pid(NULL,MFGR_ID,DEV_ID);
if (!dh) {
errx(1,”\n\nERROR: Cannot connect to device %d\n\n”,DEV_ID);
}
// set fields for the setup packet as needed
uint8_t bmReqType = 0; // the request type (direction of transfer)
uint8_t? bReq = 0; // the request field for this packet
uint16_t? wVal = 0; // the value field for this packet
uint16_t? wIndex = 0; // the index field for this packet
unsigned char*? data = ‘ ‘; // the data buffer for the in/output data
uint16_t? wLen = 0; // length of this setup packet
unsigned int? to?= 0; // timeout duration (if transfer fails)
// transfer the setup packet to the USB device
int config =
libusb_control_transfer(dh,bmReqType,bReq,wVal,wIndex,data,wLen,to);
if (config < 0) {
errx(1,”\n\nERROR: No data transmitted to device %d\n\n”,DEV_ID);
}
// now you can use libusb_bulk_transfer to send raw data to the device
libusb_exit(NULL);
}
