Re: [Discuss-gnuradio] Using USRP w/o Daughterboard's

[Eric Blossom]

On Fri, Nov 04, 2005 at 02:40:06PM -0700, Robitaille, Michael wrote:
> > > frequencies to get the data rate up some.  Based on my current 
> > > specification, none of the DB would be of much use so I am trying to 
> > > use the USRP w/o daughterboard's.
> 
> John's response
>> Don't.  Use the Basic daughterboards.  The main board itself has no useful
>> connectors for hooking up your
>> signals.  The Basic daughterboards translate the high-pin-count
>> daughterboard connector to a couple of SMA
>> connectors and to a bunch of debug headers.
>  
> 
> I modified a connector to input the signal at the same daughterboard pins
> (pins 60 and 62) that the J18 connector feeds basically bypassing the
> transformer.  The only problem is that the software is looking for the card,
> most likely getting a signal from the eeprom chip that identifies the board.
> There is no real processing or substantial signal conditioning on the board
> (only takes an unbalance input and converts it to balance).  If I could just
> bypass the software that looks for the eeprom respond, I could just use my
> modified 64 pin connector to connect to the USRP.

Why do you think that code will need to be modified?

You'll want to look at the AD9862 data sheet to work out the right
interface between the 9862 and your circuitry.  VIN+ and VIN- from the
9862 run directly to the daughterboard.

> Could you please point me to a reference of how I can modify the Basic RX
> DB?  I looked and could not find it on this board so far.

Are you talking about the h/w or the s/w?

The Basic Rx code is contained in gr-usrp/src/db_basic.py

> Thanks,
> Mike

Eric