Yes, connecting to SPI is an interesting option. We'll consider looking at it. Is there any documentation for this bus available?
On Mon, Sep 28, 2009 at 20:00, Tim Pearce <[email protected]> wrote: > In terms of integrating more tightly with the USRP/GnuRadio > > You could (maybe) just use the SPI pins and one of the digital IO lines as > the enable (the ATMega8 running as a slave) > > That way theres functions to communicate with the chip already built in you > just need to define the various commands etc? > > Tim. > > On Sun, Sep 27, 2009 at 9:53 PM, Alexander Chemeris > <[email protected]> wrote: >> >> Hi Matt, >> >> On Fri, Sep 25, 2009 at 05:20, Matt Ettus <[email protected]> wrote: >> > Alexander Chemeris wrote: >> >> We're creating a clocking unit which will be easy to use with >> >> USRP. If there will be enough interest from the community we >> >> can order some amount of PCBs and put them for sale alone or >> >> soldered and ready to use. This should be useful for everyone >> >> trying to run OpenBTS, working with GPS and everyone else >> >> who need to re-clock their USRP or have more clock precision. >> >> >> >> We've created it to run USRP at 52MHz with 0.3-0.5ppm after >> >> calibrating or 1ppm in long term without recalibrating, but actually >> >> it will support 2.84-65.83MHz, 65.91-71.82MHz, 72.5-79MHz clock >> >> ranges with about the same precision. >> > >> > I don't know what part you are planning to use for this, but it looks >> > like a >> > tunable oscillator, which is likely to have a lot of jitter. To avoid >> > problems, you would need something with less than 1 picosecond of >> > jitter. >> > The crystal on there now has about 250 femtoseconds of jitter. >> > >> > I would strongly suggest that you use a plain old tcxo, and pick a part >> > which is available in many different frequencies. This would result in >> > a >> > much cleaner output, and much less complexity. >> >> Thank you for your input. Our unit is based on low-noise National's >> VCO+PLL >> sourced from precise reference generator. Of course, all phase noises are >> taken >> into account. I need to check with my collaborator who're actually doing >> this >> work to get exact numbers. I'll post them here a bit later. >> >> -- >> Regards, >> Alexander Chemeris. >> >> >> _______________________________________________ >> Discuss-gnuradio mailing list >> [email protected] >> http://lists.gnu.org/mailman/listinfo/discuss-gnuradio > > -- Regards, Alexander Chemeris. SIPez LLC. SIP VoIP, IM and Presence Consulting http://www.SIPez.com tel: +1 (617) 273-4000 _______________________________________________ Discuss-gnuradio mailing list [email protected] http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
