Re: [Patch-gnuradio] FPGA clock frequency option for usrp_fft.py

[Alexander Chemeris]

On Sat, Feb 13, 2010 at 02:53, Eric Blossom <address@hidden> wrote:
> On Sat, Feb 13, 2010 at 02:38:26AM +0300, Alexander Chemeris wrote:
>> Is it possible to reflash it quickly then? With our ClockTamers you can
>> change frequency even in real-time, without stopping USRP.
>
> I don't think you'd wants to reflash the frequently.  I was thinking
> of a one time change.

I think most people will be happy with just one time setting. But
as practice show, some people want strange things and it's
better to let them do. :)

> In general, I was thinking that instead of changing all the apps in
> the world to support the option, you'd want to store the fpga clock
> rate in a single place.  Another way to get the info is to use an
> environment variable.  This does have the disadvantage that it's not
> directly correlated to the USRP that you're using.  (This might matter
> if you had two usrps, one with modidified clock and one without.)

I like the idea of storing FPGA freq in USRP itself. I had the same
thoughts as you, but I have no idea about USRP internal structure,
I know there are some EEPROMs on BDs. Is there one on USRP
too?

After some thought, I think it will be convenient to leave existing
set*freq() method, but read default from USRP (or default to 64MHz
if value can't be read).

-- 
Regards,
Alexander Chemeris.