I'm not sure what "spare variable timing" means, but the protocol does have a random backoff 'feature' for CDMA (or whatever the correct Multi-Letter-Acronym is). Another delay might be due to something sampling the SPI bus for other activity. Can you verify that no other SPI access is being attempted?
MS Carlos Gil Soriano wrote: > Hi Michael, > > You're right regarding to SPI problems. I don't expect to find problems > with SPI in micaz. I've been testing continuous sending in cc2420 in > micaz and, after carefully read data sheet and all code (line by line), > there's one spare "variable timing". The value of this timing moves from > 200 us to 2000 us. > > I have requested further information of 2420 to Texas so as to discern > if that timing belongs to radio transceiver or not. I'm waiting to hear > from them. Anyway, I get the impression that this timing is excessive > for 2420, so here it comes SPI bus. > > Another issue comes with CC2420 in imote2. I've found out that when you > try continuous sending in imote2 with a payload greater than 80 bytes it > fails. I do know why but it does so (at least in a couple of programs > that I've made). I feel that the source of that kind of problem could be > SPI bus, too (I haven't check timings, but I suppose that the "variable > timing" should be considerably higher). > > I'm a newbie in SPI studying. So I would appreciate any kind of help. > > Regards, > Carlos > > 2009/6/5 Michael Schippling <[email protected] <mailto:[email protected]>> > > I think it's one of those little lapses that makes TOS so intriguing. > Xbow seems to have chosen not to publish a full schematic, only the > bits that changed from the mica2 when they added the different radio. > So what's on that 2420 radio page is probably the best you'll find. > I do remember something about the SPI lines needing to have pull-ups > added in order to work correctly with external devices... > > I'm just about to embark on my SPI learning curve so I can't > pontificate, > but I'd be surprised if there were timing problems due to hardware that > behaves according to spec. > > > MS > > > Carlos Gil Soriano wrote: > > Thank you very much Michael, > > what I am looking for it is the way in which all the SPI modules > are interconnected. I am studying timings in CC2420 > architectures and I have found one timing that should be caused > by SPI factors. > > Before starting to read carefully all the code which involves > SPI bus I would like to know micaz schematic to clear up my > mind. I would like something similar to the mica schematics > found at http://www.tinyos.net/scoop/special/hardware. > > Thanks for your help, > Carlos > > 2009/6/2 Michael Schippling <[email protected] > <mailto:[email protected]> <mailto:[email protected] > <mailto:[email protected]>>> > > > I thought it was in the User's Manual: > > > http://www.xbow.com/Support/Support_pdf_files/MPR-MIB_Series_Users_Manual.pdf > but you need to piece it together using the mica2 bits as > well. I have a > nice mica2 schematic here: > http://www.etantdonnes.com/Motes/mica2_sch.pdf > which I can't find at: > http://www.tinyos.net/scoop/special/hardware > anymore. Maybe that will help a bit. > > MS > > Carlos Gil Soriano wrote: > > Hi everyone, > > I was looking for the schematics of MICAz but I've found > nothing. Do you know where I can find them? I've taken a > look to > xbow site but it only appears a few parts of the > schematic, not > the whole one. > > Regards, > Carlos > > > > > ------------------------------------------------------------------------ > > _______________________________________________ > Tinyos-help mailing list > [email protected] > <mailto:[email protected]> > <mailto:[email protected] > <mailto:[email protected]>> > > > > https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help > > > _______________________________________________ Tinyos-help mailing list [email protected] https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help
