[Tinyos-help] 802.15.4

Jan Hauer hauer at tkn.tu-berlin.de
Mon Nov 22 06:48:44 PST 2010


CAP (slotted CSMA-CA) is implemented. CFP (=GTS) is not yet
implemented, but I guess it will be in near future, because different
people seem to be implementing it.

Jan

On Fri, Nov 19, 2010 at 3:54 AM, Daniel Schnit <daniel.schnit at gmail.com> wrote:
> Hi all,
> Thanks for help! But i have one more question, in tinyOs CAP, CFP and GTS
> are implement? if are, how can i use?
> Thanks,
> Best regards.
> On Thu, Nov 18, 2010 at 7:48 PM, Pablo Marcos Oltra
> <pablo.marcos.oltra at gmail.com> wrote:
>>
>> Hi,
>> Thank you very much for your response Aitor. I had two motes running for 3
>> days with BO=14 and I had no problems of sync using the TestSync
>> application. Not even one beacon was missed. This was the first test I ran
>> to check if I was about to have clock drift problems in later experiments.
>> I'm currently using channels 19 and 20 because in my building there are just
>> a few spare channels to use (20  are mainly being used right now). Besides,
>> I always set up BO and SO < 7, using usually 5, but not even that way works
>> properly.
>> Anyway, I don't really know if it has something to do with using timers,
>> but I have noticed that the losing of the sync is kind of periodically. I
>> have noticed today as well that both devices lose sync even if they don't
>> even start at the same time (I was hoping a different periodicity for each
>> one), but they both were losing the same beacons. Hence, I'm thinking right
>> now about the possibility that it has something to do with the coordinator,
>> cause the other two devices are not even tx packets, just trying to me sync
>> with the coordinator.
>> I sent another mail a few days ago to the tinyos-help list cause I thought
>> that maybe the problems were cause because I was using printf to debug the
>> application, but without using it is losing sync as well, so... now I'm the
>> one that is lost :S.
>> Could you please check if the application attached is working for you? It
>> is just the original TestData but with a Timer that once is fired sends the
>> packets. When I try that, the device loses sync after a while.
>> Thank you very much in advance.
>> Regards,
>>   Pablo
>> 2010/11/18 Aitor Hernandez <aitorhh at kth.se>
>>>
>>> Hi,
>>> We have been using this implementation for several wireless process and
>>> we made a performance evaluation of it. We haven't found any problem with
>>> the timers (used to start a transmission, or something else). The idea that
>>> comes up is that maybe there are some interferences on the same channel that
>>> you are using or you have a high beacon order.
>>> As we have seen, if we receive packets on the period where we are waiting
>>> the beacon, we could miss them. Moreover I've just realized that by using a
>>> high beacon order (> 10) some motes could have problems to synchronize with
>>> the beacon. I guess that I could be due to the clock drift, but Jan can
>>> clarify this point.
>>> What I recommend you, is to use a BO=6 and a SO =5,6 with this values you
>>> shouldn't have any problems.... Furthermore, try to change the channel and
>>> see if the problem persists. Channels between 22 and 26 don't have any
>>> overlapping with WiFi channels.
>>> At the moment, there is nothing else in my mind. I hope it will work for
>>> you.
>>> Good luck!
>>>
>>> On 18 November 2010 16:27, Pablo Marcos Oltra
>>> <pablo.marcos.oltra at gmail.com> wrote:
>>>>
>>>> I found the error and the UserButton is now working in my test
>>>> application. So, I wait for 3 nodes to have synchronization and then I push
>>>> all of their buttons and they start tx data. However, after a while, they
>>>> lose sync, as always, and I don't know why.
>>>> Aitor, have you ever used timers that once they're fired they send the
>>>> data (for example, to send data every minute or so)? Cause I'm having
>>>> trouble with that (even with just one device), and don't if that could be
>>>> something related with the problem you told us a few mails ago.
>>>> Regards,
>>>>   Pablo
>>>> 2010/11/18 Aitor Hernandez <aitorhh at kth.se>
>>>>>
>>>>> In my case, I just program all the motes at the same time by using "&"
>>>>> function on the shell, something like:
>>>>> $ make tmote
>>>>> $ make tmote reinstall,1 bsl,/dev/ttyUSB1 & make tmote
>>>>> reinstall,2 bsl,/dev/ttyUSB2
>>>>> By the way, I've been using the UserButton for some time, and I've
>>>>> never noticed the behaviour you explain, with or without TKN154_DEBUG
>>>>> enabled.
>>>>> Best,
>>>>> Aitor
>>>>>
>>>>> On 18 November 2010 13:28, Pablo Marcos Oltra
>>>>> <pablo.marcos.oltra at gmail.com> wrote:
>>>>>>
>>>>>> May I add other option to the Aitor ones?
>>>>>> I thought about letting the motes synchronize first, and then start
>>>>>> sending packets once they're all synchronized. How could you do this? I have
>>>>>> tried doing that with the telosb user button, hence once you pressed it you
>>>>>> change a flag that starts sending packets. The problem is that I have just
>>>>>> been able to do that with the TKN154_DEBUG enabled, otherwise, the event
>>>>>> void Notify.notify( button_state_t state ) is not working.
>>>>>> You can see an example of how to use the telosb user button in
>>>>>> $TOSROOT/apps/tests/telosb.
>>>>>> Regards,
>>>>>>   Pablo
>>>>>> 2010/11/18 Jan Hauer <hauer at tkn.tu-berlin.de>
>>>>>>>
>>>>>>> yes - I can reproduce the problem and also believe that it is due to
>>>>>>> wrong (beacon) timestamps. will look into it and try to fix it asap.
>>>>>>>
>>>>>>> thanks,
>>>>>>> jan
>>>>>>>
>>>>>>> On Thu, Nov 18, 2010 at 10:02 AM, Aitor Hernandez <aitorhh at kth.se>
>>>>>>> wrote:
>>>>>>> > Hi guys,
>>>>>>> > I've seen this problem with TKN15.4. It is possible to synchronize
>>>>>>> > N nodes
>>>>>>> > with TKN15.4 the problem is that they need to start the app at the
>>>>>>> > same
>>>>>>> > time. From my experience I've realized that the problem comes from
>>>>>>> > the
>>>>>>> > cc2420_tkn154 (maybe it happens with the default cc2420
>>>>>>> > implementation as
>>>>>>> > well).
>>>>>>> > If we have a network with N nodes running and transmitting data
>>>>>>> > between
>>>>>>> > them, when we try to add another node we could have this problem.
>>>>>>> > As far as
>>>>>>> > we have the radio enabled for reception for a long period (Scan
>>>>>>> > period), the
>>>>>>> > cc2420 receives the beacons but data packets as well. Once it
>>>>>>> > detects that
>>>>>>> > the received packet is a beacon, it sets the timestamp, but
>>>>>>> > sometimes the
>>>>>>> > timestamp is wrong, due to the data packets, and then we lost the
>>>>>>> > next
>>>>>>> > beacons.
>>>>>>> > Possible solutions:
>>>>>>> >
>>>>>>> > Check the CC2420ReceiveP.nc and the m_timestamp_queue. I guess that
>>>>>>> > the
>>>>>>> > problem should be there. I did some modifications on
>>>>>>> > the CC2420ReceiveP.nc to solve this problem, but I haven't test it
>>>>>>> > properly.
>>>>>>> > If we lost the synchronization, scan again
>>>>>>> > with MLME_SCAN.request(). It is a
>>>>>>> > "fake" solution, because the problem is still there, but for some
>>>>>>> > app it
>>>>>>> > will work.
>>>>>>> > Start the nodes at the same time. It is not possible in a real
>>>>>>> > deployment.
>>>>>>> >
>>>>>>> >
>>>>>>> > --
>>>>>>> > Aitor Hernandez
>>>>>>> > KTH | Automatic Control
>>>>>>> > Research engineer
>>>>>>> > Stockholm
>>>>>>> > Phone:  +46 (0)704 26 87 99
>>>>>>> >
>>>>>>> > _______________________________________________
>>>>>>> > Tinyos-help mailing list
>>>>>>> > Tinyos-help at millennium.berkeley.edu
>>>>>>> >
>>>>>>> > https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help
>>>>>>> >
>>>>>>>
>>>>>>> _______________________________________________
>>>>>>> Tinyos-help mailing list
>>>>>>> Tinyos-help at millennium.berkeley.edu
>>>>>>>
>>>>>>> https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help
>>>>>>
>>>>>
>>>>>
>>>>>
>>>>> --
>>>>> Aitor Hernandez
>>>>> KTH | Automatic Control
>>>>> Research engineer
>>>>> Stockholm
>>>>> Phone:  +46 (0)704 26 87 99
>>>>
>>>
>>>
>>>
>>> --
>>> Aitor Hernandez
>>> KTH | Automatic Control
>>> Research engineer
>>> Stockholm
>>> Phone:  +46 (0)704 26 87 99
>>
>>
>> _______________________________________________
>> Tinyos-help mailing list
>> Tinyos-help at millennium.berkeley.edu
>> https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help
>
>



More information about the Tinyos-help mailing list