Install libusb
-
sudo apt-get install libusb-1.0-0-dev
You can check it is there
-
ls /usr/include/libusb-1.0
Write Scan C++ Program
Write a program to scan for devices.
Create a file scanusb.cpp
-
#include <iostream>
-
#include <libusb-1.0/libusb.h>
-
using namespace std;
-
-
void printdev(libusb_device *dev);
-
-
int main()
-
{
-
std::cout << "Hello World!" << std::endl;
-
-
libusb_device **devs; //pointer to pointer of device, used to retrieve a list of devices
-
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 a library session
-
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
-
}
-
cout<<cnt<<" Devices in list."<<endl; //print total number of usb devices
-
-
ssize_t i; //for iterating through the list
-
for(i = 0; i < cnt; i++) {
-
printdev(devs[i]); //print specs of this device
-
}
-
libusb_free_device_list(devs, 1); //free the list, unref the devices in it
-
libusb_exit(ctx); //close the session
-
-
return 0;
-
}
-
-
void printdev(libusb_device *dev) {
-
libusb_device_descriptor desc;
-
int r = libusb_get_device_descriptor(dev, &desc);
-
if (r < 0) {
-
cout<<"failed to get device descriptor"<<endl;
-
return;
-
}
-
cout<<"Number of possible configurations: "<<(int)desc.bNumConfigurations<<" ";
-
cout<<"Device Class: "<<(int)desc.bDeviceClass<<" ";
-
cout<<"VendorID: "<<desc.idVendor<<" ";
-
cout<<"ProductID: "<<desc.idProduct<<endl;
-
libusb_config_descriptor *config;
-
libusb_get_config_descriptor(dev, 0, &config);
-
cout<<"Interfaces: "<<(int)config->bNumInterfaces<<" ||| ";
-
const libusb_interface *inter;
-
const libusb_interface_descriptor *interdesc;
-
const libusb_endpoint_descriptor *epdesc;
-
for(int i=0; i<(int)config->bNumInterfaces; i++) {
-
inter = &config->interface[i];
-
cout<<"Number of alternate settings: "<<inter->num_altsetting<<" | ";
-
for(int j=0; j<inter->num_altsetting; j++) {
-
interdesc = &inter->altsetting[j];
-
cout<<"Interface Number: "<<(int)interdesc->bInterfaceNumber<<" | ";
-
cout<<"Number of endpoints: "<<(int)interdesc->bNumEndpoints<<" | ";
-
for(int k=0; k<(int)interdesc->bNumEndpoints; k++) {
-
epdesc = &interdesc->endpoint[k];
-
cout<<"Descriptor Type: "<<(int)epdesc->bDescriptorType<<" | ";
-
cout<<"EP Address: "<<(int)epdesc->bEndpointAddress<<" | ";
-
}
-
}
-
}
-
cout<<endl<<endl<<endl;
-
libusb_free_config_descriptor(config);
-
}
Compile and run
Find g++ options for libusb:
-
pkg-config --libs libusb-1.0
Build with g++
-
g++ scanusb.cpp -lusb-1.0
Run
-
./a.out
USB Permission
The USB device can only be opened by root.
-
lsusb -v -d 1267:0000
This gives permission error in output (Couldn't open device, some information will be missing)
Add a line to
sudo nano /etc/udev/rules.d/40-scratch.rules
-
ATTRS{idVendor}=="1267", ATTRS{idProduct}=="0000", SUBSYSTEMS=="usb", ACTION=="add", MODE="0666", GROUP="plugdev"
Repeast the lsusb test and there will be no couldn't open device message!
RJM Article Type
Work Notes