Re: [Discuss-gnuradio] Claiming interface 2 (RX) fails!

[Ujala Qasim]

Hi,

Well I am implementing the given task by picking up selected function from usrp_prims, usrp_standard, usrp_basic and fusb_generic etc in a program of my own. As these are just simple classes which define particular functions, I was confused and could not very much clearly understand that in which order should I be calling all those functions defined in the above mentioned classes because they are so inter-related. So I implemented my own program according to my own understanding (which I am not re-writing, just picking up function definitions from the classes) which follows these basic steps:

1. running libusb core functions first:

  

  usb_init(); /* initialize the library */

  usb_find_busses(); /* find all busses */

  usb_find_devices(); /* find all connected devices */

 as done in usrp_primss.cc in usrp_one_time_init()

2. then find the device on the bus and open it using usb_open()

    usb_dev_handle *open_dev(void)

{

  struct usb_bus *bus;

  struct usb_device *device;

  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)

            {

 myDev = device;

              return usb_open(device);

            }

        }

    }

  return NULL;

}

as done in usrp_prims.cc in struct usb_device *usrp_find_device (int nth, bool fx2_ok_p)

3. Then open USRP command interface by calling following functions:

    if(usb_set_configuration(udh, 1) < 0)

    {

      printf("error: setting config 1 failed\n");

      usb_close(udh);

      return 0;

    }

  if(usb_claim_interface(udh, 0) < 0 )

    {

      printf("error: claiming interface 0 failed\n");

      usb_close(udh);

      return 0;

    }

as done in usrp_prims.cc in usrp_open_interface (struct usb_device *dev, int interface, int altinterface) by calling usrp_open_cmd_interface (struct usb_device *dev)

4. Then open USRP RX interface by calling following functions:

    

    Where bulk_udh is a usb device handle for RX interface.

    if(!(bulk_udh = usb_open(myDev)))

    {

      printf("error: device not found!\n");

      return 0;

    }

if(usb_set_configuration(bulk_udh, 1) < 0)

    {

      printf("error: setting config 1 failed\n");

      usb_close(bulk_udh);

      return 0;

    }

if (usb_claim_interface (bulk_udh, USRP_RX_INTERFACE) < 0){

printf("error: claming interface failed!\n");

    usb_close (bulk_udh);

    return 0;

  }

  if (usb_set_altinterface (bulk_udh,USRP_RX_ALTINTERFACE) < 0){

    printf("error: setting altinterface failed!\n");

    usb_release_interface (bulk_udh, USRP_RX_INTERFACE);

    usb_close (bulk_udh);

    return 0;

  }

as done in usrp_prims.cc in usrp_open_interface (struct usb_device *dev, int interface, int altinterface) by calling usrp_open_rx_interface (struct usb_device *dev)

but here the bulk_udh fails to claim the interface

5. Then calling the functions:

    set_rx_freq (0, 0);

  set_nchannels (1);

  set_pga (0, 0);

  set_mux(0x32103210); // Board A only

  set_decim_rate(8);

  set_ddc_phase(0,0);

 from usrp_standard class

6. And performing bulk read through usb_bulk_read function

Can you please tell me if these sequence of steps is correct? And if I am going in the right direction?

Thanks.

    

On Thu, Mar 12, 2009 at 9:54 PM, Eric Blossom <address@hidden> wrote:

On Thu, Mar 12, 2009 at 09:03:23PM +0500, Ujala Qasim wrote:
> Hi!
> I am trying to write a program in C that interfaces between USRP and
> Windows, this is my initial code:

...

> However, the claiming of interface always fails on bulk_udh. Please guide me
> in this regard as to what I am doing wrong?

Instead of attempting to rewrite all of the well tested USRP C++ code
into C, have you considered writing a small shim that would create a C
friendly interface to the usrp_standard_tx and usrp_standard_rx
classes?  It is possible to write C++ code that can call C++ code, yet
is callable from C by using the C++ extern "C" { ... } feature.
Of course the C interface can only use C data types, not C++ classes.
See a good C++ book for details and/or search for "C linkage".

Please don't ask quesions about how to do this on this list.  It has
nothing to do with GNU Radio in particular, and everything to do with
generic C and C++ programming.  If you're not familiar with C++,
perhaps you can find a local C++ hacker who can assist you.  Another
approach may be to write your application in the subset of C++ that
looks pretty much like C...

Eric