[Tinyos-help] Sync problems with printf and TKN154

Pablo Marcos Oltra pablo.marcos.oltra at gmail.com
Mon Nov 15 09:03:22 PST 2010

I have been running some more tests during the day and I have noticed that
with just one timer that runs the packetSendTask with a periodicity of
250ms, makes the SYNC go away.


2010/11/15 Pablo Marcos Oltra <pablo.marcos.oltra at gmail.com>

> Thank you very much for the answer Jan.
> I did try my application commenting every printf, but even that way I had
> sync problems. Anyway, I changed the aMaxLostBeacons parameter from 4 to 1,
> so that if just one beacon is lost it will consider MLME_SYNC_LOSS. I have
> managed to reproduce the problem with the TestData example of the tkn154
> folder.
> Please find attached a .zip with the changed files inside.
> The sync problem is probably because of the Timers as well, cause there are
> no printf's in this code. I have set up a timer that is fired periodically
> each 50ms to send a packet (I know that periodicity sending data is not even
> real, but anyway, it should work) and another one that does nothing (just
> because I wanted to reproduce the same amount of timers that I have in my
> own application, one for sending packets and the other one for measuring
> time). Besides, once the device loses synchronization, it turns off all the
> leds. Afther a while that should happen (I have tried that a few times in
> TelosB motes).
> Maybe that is happening cause I'm doing something wrong, but I don't know
> what. Let's see if we can find a solution to this.
> Regards,
>   Pablo
> 2010/11/13 Jan Hauer <hauer at tkn.tu-berlin.de>
> It is not unlikely that the printf debugging causes timing problems,
>> because it involves low-level (interrupt) functions that can reduce
>> the responsiveness of e.g. the timer subsystem. Why not test your
>> application without printf and see if it works then (toggle LEDs or
>> use a sniffer to see what's happening on the channel)? If you think
>> there is an issue in tkn154 then please try to reproduce it based on
>> one of the example apps/tests/tkn154/beacon-enabled apps, preferably
>> with minimal changes.
>> Jan
>> On Fri, Nov 12, 2010 at 10:56 PM, Pablo Marcos Oltra
>> <pablo.marcos.oltra at gmail.com> wrote:
>> > Hi all,
>> > I have been trying to program an application with the TKN154 MAC
>> > implementation, intending to associate a device with the coordinator and
>> > send packets periodically. It does work, but not very well, cause the
>> device
>> > misses some beacons periodically as well (I think that is because it
>> tries
>> > to send something while it should be in rx mode). I have notice that
>> after
>> > commenting some printf's the time at which the device loses sync is
>> > different (altough periodically).
>> > So, I thought that maybe it could have something related with the
>> printf's,
>> > and that these could made that the TKN154 implementation doesn't work as
>> it
>> > would. I have read that I should just use the printfflush() in non-time
>> > critical operations, but even with no printf's my device is losing
>> > synchronization with the coordinator (but not so often).
>> > Hence, I would like to ask: has anyone experienced sync problems using
>> the
>> > printf function in time critical areas or know why I could have these
>> > problems? How could I solve that? Is there another way to debug the
>> > application without running a simulation with TOSSIM?
>> > Thank you ver much in advance.
>> > Regards,
>> >   Pablo
>> > _______________________________________________
>> > Tinyos-help mailing list
>> > Tinyos-help at millennium.berkeley.edu
>> >
>> https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help
>> >
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