Can't access usb device with libusb, crashes at usb_set_configuration()

zwiebelchen · 02-08-2011, 09:23 AM

Hi,

I'm new to linux development and I try to send a few bytes over USB to the JB media light manager (I think it doesn't matter which device it is).

My programm crashes when it comes to usb_set_configuration().
If I commit this method out (//) and let the programm invoke directly the usb_claim_interface() method it crashes, too.

I'm developing with Eclipse and I'm using the GCC C++ Compiler under Ubuntu 10.10 32bit.
lsusb tells me following:
...
Bus 005 Device 004: ID 16c0:0a32 VOTI
...

That's the device because disconnecting it makes the line disappear.

Can anyone help ?

Code:

#include <usb.h>
#include <stdio.h>
#include <iostream>

/* the device's vendor and product id */
#define MY_VID 0x16c0
#define MY_PID 0x0a32

/* the device's endpoints */
#define EP_IN 0x81
#define EP_OUT 0x01

#define BUF_SIZE 8

using namespace std;

struct usb_device *device;

usb_dev_handle *open_dev(void);

usb_dev_handle *open_dev(void)
{
  struct usb_bus *bus;

  for(bus = usb_get_busses(); bus; bus = bus->next)
    {
      for(device = bus->devices; device; device = device->next)
        {
          if(device->descriptor.idVendor == MY_VID
             && device->descriptor.idProduct == MY_PID)
            {
              return usb_open(device);
            }
        }
    }
  return NULL;
}

int main(void)
{
  usb_dev_handle *dev_handl = NULL; /* the device handle */
  char tmp[BUF_SIZE] = {0x05, 0x22, 0x01, 0x06, 0x00, 0x00, 0x00, 0x00};

  usb_init(); /* initialize the library */
  usb_find_busses(); /* find all busses */
  usb_find_devices(); /* find all connected devices */


  if(!(dev_handl = open_dev()))
    {
      printf("error: device not found!\n");
      return 0;
    }

  usb_config_descriptor *config = device->config;
  usb_interface *interface = config->interface;
  usb_interface_descriptor *altsetting = interface->altsetting;

  if(usb_set_configuration(dev_handl, config->iConfiguration) < 0)
      {
       printf("error: setting config failed\n");
      usb_close(dev_handl);
      return 0;
   }

  if(usb_claim_interface(dev_handl, altsetting->bInterfaceNumber) < 0)
    {
      printf("error: claiming interface failed\n");
      usb_close(dev_handl);
      return 0;
    }

  if(usb_bulk_write(dev_handl, EP_OUT, tmp, sizeof(tmp), 5000)
     != sizeof(tmp))
    {
      printf("error: bulk write failed\n");
    }

  if(usb_bulk_read(dev_handl, EP_IN, tmp, sizeof(tmp), 5000)
     != sizeof(tmp))
    {
      printf("error: bulk read failed\n");
    }

  usb_release_interface(dev_handl, 0);
  usb_close(dev_handl);

  return 0;
}