Thanks alot Janos! it seems to work now, it was a clumsy mistake on my side. Another Questions, make z1 CC2420x doesn't work. Do u ever have any experience with that! and also neither for UCMINI.
Regards, Wasif! On Wed, Jan 9, 2013 at 4:25 PM, Janos Sallai <janos.sal...@vanderbilt.edu>wrote: > Wasif: > > Regarding setting the backoff values to 1us in the cc2420x stack: this > clearly doesn't work, because the code would schedule an alarm 1us in the > future, which is simply not possible. By the time the operation of > scheduling the alarm completes, that time instant is going to be in the > past, and the alarm will fire after the counter overflows and reaches that > particular value again. To put it in another way: backoff values under > (approximately) 200 microseconds are not valid. > > To get rid of CSMA logic altogether, you need to remove the collision > avoidance layer altogether and rewire the stack (CC2420XRadioC.nc) as I > have described in my previous email. > > Janos > > > On Wed, Jan 9, 2013 at 5:31 AM, wasif masood <rwmas...@gmail.com> wrote: > >> >> Hi all, >> >> I am trying to measure the message delay on Telosb platform and now >> comparing the CC2420 stack with CC2420X stack. Below are the two Histograms >> showing the delay spread of Cc2420 and CC2420X stacks respectively. The >> experiment is perfromed for around 1 hr at the same time using two >> different frequency channels. >> For CC2420X I have used the TimeSyncAMSend<TMicro,uint32_t> interface >> and have calculated the delay at the receiver end as >> >> delay = call LocalTimeMicro.get() - call TimeSyncPacket.eventTime(msg) >> >> and for CC2420 Stack, I have used TimeSyncAMSend with Milli sec >> precision and have calculated the delay as : >> >> delay = call LocalTimeMilli.get() - call TimeSyncPacket.eventTime(msg) >> >> in case of CC2420 stack CCA is disabled and for CC2420X stack, I have >> changed RandomCollisionConfig implementatoin in CC2420XRadioP module in >> such a way that all types of backoff values ( Initial, minimum and >> congestion) are now just RADIO_ALARM_MICROSEC value (because I couldn't >> find a direct way to disable it). >> >> Now, what I observe is a bit interesting since the two histograms show a >> completely different delay behaviors, ie. with the Cc2420X stack the delay >> ranges between 1 to 13ms, but with CC2420X stack the delay goes from 70ms >> to 150ms. Is this also what any of you experience or is there something I >> am missing here? >> >> here are the histograms: >> >> http://s14.postimage.org/55bs7ni0x/Telosb_CC2420x.png >> >> http://s8.postimage.org/8paur8s6d/Telosb_CC2420.png >> >> >> Regards, >> Wasif Masood >> >> _______________________________________________ >> Tinyos-help mailing list >> Tinyos-help@millennium.berkeley.edu >> https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help >> > > -- Wasif Masood
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