Re: [Discuss-gnuradio] USRP2 General I/O

[Marcus D. Leech]

On 06/07/2011 12:16 PM, Brenden Smith wrote:
> I guess there's a search function for a reason; I have found a similar 
> question in the archives and I believe I have found a suitable answer. 
> Sorry for the waste of time.
There are no stupid questions, only stupid answers :-)

There are 16 general-purpose I/O lines for each of TX and RX on a 
daughtercard, although in *many* instances, some of these are
  chewed up by internal functions.

For the WBX, J15 carries GPIO signals on the granddaughter board.  The 
signals it carries are:

    o GPIO - RX4-7 and RX14,15
    o GPIO - TX5 and TX8-15

    As well as AUX_DAC_C_RX and AUX_DAC_A_RX

For other daughtercards, the GPIOs that are available for use vary quite 
a bit, and you have to be *very* careful not to change GPIO
  settings for pins other than the ones that are freely-available.

The GPIO control functions in UHD are described here:

http://www.ettus.com/uhd_docs/doxygen/html/classuhd_1_1usrp_1_1dboard__iface.html