[Tinyos-help] Sync problems with printf and TKN154

Jan Hauer hauer at tkn.tu-berlin.de
Thu Nov 18 03:14:07 PST 2010

Currently there is another tinyos-help thread (subject "802.15.4")
that might be about the same problem; once that's fixed maybe your
problem is solved as well.


On Thu, Nov 18, 2010 at 11:24 AM, Pablo Marcos Oltra
<pablo.marcos.oltra at gmail.com> wrote:
> Hi all,
> Has anyone been able to reproduce the same sync problem I had with timers
> and the tkn154? Thanks in advance.
> Regards,
>   Pablo
> 2010/11/15 Pablo Marcos Oltra <pablo.marcos.oltra at gmail.com>
>> 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.
>> Regards,
>>   Pablo
>> 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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