[Tinyos-devel] improving FTSP interface

[Omprakash Gnawali]

On Wed, Aug 6, 2008 at 10:38 PM, Miklos Maroti <mmaroti at math.u-szeged.hu> wrote:
> On Thu, Aug 7, 2008 at 7:32 AM, Omprakash Gnawali <gnawali at usc.edu> wrote:
>> On Wed, Aug 6, 2008 at 10:22 PM, Miklos Maroti <mmaroti at math.u-szeged.hu> wrote:
>>>> It would be nice for FTSP to provide a rollover bit so that the
>>>> applications know that the time has wrapped around since the last the
>>>> time was read.
>>>
>>> Why would you want that? In a 32-bit global time you can regard the
>>> highest bit as a rollover indicator, whenever that value has changed
>>> from 1 to 0 then you have  a rollover.
>>
>> That bit might change for reasons other than a rollover.
>
> But realize, the 33rd bit (which is what you are asking for) might
> change for other reasons as well. How can FTSP detect a rollover
> internally? If your timesync is so much messed up that it cannot
> distinguish a rollover from a simple 2^31 unit time offset change,
> then you should not rely on it in the first place. Trust me, just
> watch the 32nd bit, and tell me a concrete scenario when that is not
> working.

It is much easier for FTSP to realize if it is a rollover or other
reasons than an application. I think this is different from 33rd bit.

Yes, we run FTSP in scenarios where something more than the 32nd or
33rd bit would be useful and seems necessary - a bit that takes into
account the FTSP state machine as well as the counter value.

- om_p