Re: [Discuss-gnuradio] USRP aux_dac

[Angilberto Muniz Sb]

Good to know there is a solution...

Matt, when you say "You'll need to have
 the FX2 STOP driving them before you make the FPGA
drive them", you mean I'll have to break the wires
between FX2 and AD9862 or you mean I'll have the
modify the FX2 firmware so to make the AD9862
controllable by both the FX2 and the FPGA?


Angilberto.


--- Matt Ettus <address@hidden> wrote:

> Angilberto Muniz Sb wrote:
> 
> >Hi All,
> >
> >Im working on a project that needs a continuos
> update
> >of a slow varying DC signal. I was able to realize
> >part of the project and put it into the FPGA. Now I
> >need a way to update the AUX_DAC port on the 9862,
> but
> >aparently that is handled by the USB uController !
> Is
> >that correct ? To set up the AUX_DAC do DO have to
> >waste USB bandwidth?  (My intent was to use the PC
> >just to download the FPGA image, do some setup and
> the
> >USRP should run by itself...)
> >Please shade some light...
> >  
> >
> 
> The USRP is wired such that only the FX2 can control
> the AD9862s. 
> 
> You can change this by adding R2001, R2004, and
> R2005 to the USRP.  All 
> should be Zero-ohm resistors.  Be careful, because
> you will now have 
> multiple drivers of these nets.  You'll need to have
> the FX2 STOP 
> driving them before you make the FPGA drive them.
> 
> This will allow the FPGA to control the AD9862s. 
> You can also make the 
> FPGA control the tuning of the RFX-series
> daughterboards.  Send me mail 
> if you need that.
> 
> Matt
> 
> 


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