[Tinyos-help] LPL syncronization

Roman Lim rlim at ee.ethz.ch
Wed Feb 20 04:05:07 PST 2008


Murray, Ben wrote:
> Hi
> Am I correct in thinking your tinyos-2.x-contrib/ethz/snpk/tos/chips/cc2420/
> setup is basically keeping a table of neighbour wake-up times for more
> efficient unicasts rather than trying to align their wake-up times?

yes, this is correct

> I have been looking at the /ethz/snpk contrib, and also found
> ethz\snpk\tos\lib\net\TimeSync  which looks like it's trying to align clocks
> (or at least the mote's view of a global clock) although it appears to
> expect the nodes being physically arranged by ID? Sort of similar to FTSP
> approach?

i think you are right (i don't know every detail about this 
implementation). in the current state, information propagates in 
ascending node id order. this was done for testing reasons, and since 
then, we didn't change this code.


> Regards,
> Ben
>> -----Original Message-----
>> From: Roman Lim [mailto:rlim at ee.ethz.ch]
>> Sent: 20 February 2008 09:58
>> To: Murray, Ben
>> Cc: tinyos-help at millennium.berkeley.edu; 'Brian Jump'
>> Subject: Re: [Tinyos-help] LPL syncronization
>> the sensor network platform kit (SNPK) has a synchronous LPL 
>> implementation for CC2420.
>> you can download it at
>> http://tinyos.cvs.sourceforge.net/tinyos/tinyos-2.x-contrib/et
>> hz/snpk/tos/chips/cc2420/
>> it is based on the most recent tos2 cc2420 radio stack
>> its actually developed for tmotes, micaz is not tested.
>> roman
>> Murray, Ben wrote:
>>> as far as I am aware LPL is asynchronous. The TEP is here:
>>> http://www.tinyos.net/tinyos-2.x/doc/html/tep105.html
>>> and tutorials are here:
>>> http://www.tinyos.net/tinyos-2.x/doc/html/tutorial/
>>> I have, however, read in the contrib about "synchronous" 
>> LPL (rincon)
>> http://docs.tinyos.net/index.php/TinyOS_2.x_index_of_contribut
> ed_code#Rincon
>> _Enhanced_CC2420_Radio_Stack
>> ...it appears to use a system of recording neighbour-schedules and times
> its
>> preambles such that they start just before it thinks the intended
> recipient
>> is to wake up, thus reducing the length of the preamble required
> (recipients
>> can ACK a unicast to stop the senders preamble continuing longer than
>> necessary).
>> If you find anything else useful wrt LPL-style synchronous stuff please
>> share!
>> Cheers
>> -Ben
>>> I have recently started working with TinyOS on the micaZ motes.  I am 
>>> trying to implement the Low Power Listening that comes with 
>>> TinyOS.  I 
>>> just have a few questions on how it works.  What is the best way to 
>>> determine the duty cycle for the LPL.  How do the motes stay 
>>> synchronized? 
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