我正在尝试运行此程序以使用libusb发送数据。我无法找到USB端口的端点。 libusb_bulk_transfer函数中需要此参数。
#include <iostream>
#include <libusb.h>
using namespace std;
int main() {
libusb_device **devs; //pointer to pointer of device, used to retrieve a list of devices
libusb_device_handle *dev_handle; //a device handle
libusb_context *ctx = NULL; //a libusb session
int r; //for return values
ssize_t cnt; //holding number of devices in list
r = libusb_init(&ctx); //initialize the library for the session we just declared
if(r < 0) {
cout<<"Init Error "<<r<<endl; //there was an error
return 1;
}
libusb_set_debug(ctx, 3); //set verbosity level to 3, as suggested in the documentation
cnt = libusb_get_device_list(ctx, &devs); //get the list of devices
if(cnt < 0) {
cout<<"Get Device Error"<<endl; //there was an error
return 1;
}
cout<<cnt<<" Devices in list."<<endl;
dev_handle = libusb_open_device_with_vid_pid(ctx, 5118, 7424); //these are vendorID and productID I found for my usb device
if(dev_handle == NULL)
cout<<"Cannot open device"<<endl;
else
cout<<"Device Opened"<<endl;
libusb_free_device_list(devs, 1); //free the list, unref the devices in it
unsigned char *data = new unsigned char[4]; //data to write
data[0]='a';data[1]='b';data[2]='c';data[3]='d'; //some dummy values
int actual; //used to find out how many bytes were written
if(libusb_kernel_driver_active(dev_handle, 0) == 1) { //find out if kernel driver is attached
cout<<"Kernel Driver Active"<<endl;
if(libusb_detach_kernel_driver(dev_handle, 0) == 0) //detach it
cout<<"Kernel Driver Detached!"<<endl;
}
r = libusb_claim_interface(dev_handle, 0); //claim interface 0 (the first) of device (mine had jsut 1)
if(r < 0) {
cout<<"Cannot Claim Interface"<<endl;
return 1;
}
cout<<"Claimed Interface"<<endl;
cout<<"Data->"<<data<<"<-"<<endl; //just to see the data we want to write : abcd
cout<<"Writing Data..."<<endl;
r = libusb_bulk_transfer(dev_handle, (2 | LIBUSB_ENDPOINT_OUT), data, 4, &actual, 0); //my device's out endpoint was 2, found with trial- the device had 2 endpoints: 2 and 129
if(r == 0 && actual == 4) //we wrote the 4 bytes successfully
cout<<"Writing Successful!"<<endl;
else
cout<<"Write Error"<<endl;
r = libusb_release_interface(dev_handle, 0); //release the claimed interface
if(r!=0) {
cout<<"Cannot Release Interface"<<endl;
return 1;
}
cout<<"Released Interface"<<endl;
libusb_close(dev_handle); //close the device we opened
libusb_exit(ctx); //needs to be called to end the
delete[] data; //delete the allocated memory for data
return 0;
}
以下是我的主机PC上接收数据的程序。
#include<stdio.h>
#include<unistd.h>
#include<string.h>
#include <sys/stat.h>
#include <fcntl.h>
void main()
{
read_port();
//return 0;
}
read_port(void)
{
int fd = open("/dev/ttyACM0", O_RDONLY | O_NOCTTY);
if (fd == -1)
{
/* Could not open the port. */
perror("open_port: Unable to open /dev/ttyACM0) - ");
}
char buffer[32];
for(;;)
{
int n = read(fd, buffer, sizeof(buffer));
if (n < 0)
fputs("read failed!\n", stderr);
printf("\n %d", n);
}
}
请帮忙。 提前谢谢。
答案 0 :(得分：1)
在回答您的实际问题时，如果您想知道设备附带了哪些实际端点，lsusb就是您的朋友
如果您不确定设备的供应商和设备ID是什么，请输入：
lsusb
你会得到这样的东西：
Bus 001 Device 005: ID 093a:2510 Pixart Imaging, Inc. Optical Mouse
Bus 001 Device 015: ID 413c:2003 Dell Computer Corp. Keyboard
Bus 001 Device 020: ID 0483:3748 STMicroelectronics ST-LINK/V2
Bus 001 Device 002: ID 8087:0020 Intel Corp. Integrated Rate Matching Hub
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
假设我们想知道ST-LINK / V2上有哪些端点，我们使用-v选项在详细模式下使用lsusb，并使用-d选项仅指定我们感兴趣的设备ID：
lsusb -v -d 0483:3748
我们将从中获得一个很大的字段列表。拓扑大致是：
device->configuration->interface->endpoints
| interface->endpoints
| interface->endpoints
|
->configuration->interface->endpoints
interface->endpoints
...
所以找到你想要使用的界面（通常是0）：
找到接口描述符
可以看到端点描述符
然后查找术语bEndpointAddress以获取实际值
在这种情况下，我们在端点中有一个批量地址为0x81：
bEndpointAddress 0x81 EP 1 IN
还有一点下来：
bEndpointAddress 0x02 EP 2 OUT
另一个在端点：
bEndpointAddress 0x83 EP 3 IN
为了完整性，这里是完整转储：
总线001设备020：ID 0483：3748 STMicroelectronics ST-LINK / V2
Device Descriptor:
bLength 18
bDescriptorType 1
bcdUSB 2.00
bDeviceClass 0 (Defined at Interface level)
bDeviceSubClass 0
bDeviceProtocol 0
bMaxPacketSize0 64
idVendor 0x0483 STMicroelectronics
idProduct 0x3748 ST-LINK/V2
bcdDevice 1.00
iManufacturer 1 STMicroelectronics
iProduct 2 STM32 STLink
iSerial 3 000000000001
bNumConfigurations 1
Configuration Descriptor:
bLength 9
bDescriptorType 2
wTotalLength 39
bNumInterfaces 1
bConfigurationValue 1
iConfiguration 0
bmAttributes 0x80
(Bus Powered)
MaxPower 100mA
Interface Descriptor:
bLength 9
bDescriptorType 4
bInterfaceNumber 0
bAlternateSetting 0
bNumEndpoints 3
bInterfaceClass 255 Vendor Specific Class
bInterfaceSubClass 255 Vendor Specific Subclass
bInterfaceProtocol 255 Vendor Specific Protocol
iInterface 4 ST Link
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x81 EP 1 IN *!eg end point address!*
bmAttributes 2
Transfer Type Bulk
Synch Type None
Usage Type Data
wMaxPacketSize 0x0040 1x 64 bytes
bInterval 0
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x02 EP 2 OUT
bmAttributes 2
Transfer Type Bulk
Synch Type None
Usage Type Data
wMaxPacketSize 0x0040 1x 64 bytes
bInterval 0
Endpoint Descriptor:
bLength 7
bDescriptorType 5
bEndpointAddress 0x83 EP 3 IN
bmAttributes 2
Transfer Type Bulk
Synch Type None
Usage Type Data
wMaxPacketSize 0x0040 1x 64 bytes
bInterval 0
Device Status: 0x0000
（巴士供电）