[Tinyos-devel] FTSP testing result

[Thomas Schmid]

Has anybody tried to fix this? The timestamp queue is very ugly right
now! Especially, we basically invalidate the timestamp every time we
have more than one timestamp in that queue anyway!

Next, I think the problem for the invalidated timestamps in the
ReceiveP is in line number 324 in CC2420Transmit P. Code here
duplicated:
if ( time - m_prev_time < 10 ) {
  call CC2420Receive.sfd_dropped();
  if (m_msg)
    call PacketTimeStamp.clear(m_msg);
}

I don't really understand what this check is for, but this will always
trigger a clear on the timestamp if we fall through in the SFD. I
think this is wrong. We should only invalidate the timestamp if
SFD.get() was 0 at the time of reading the timer, not if the time
between the two interrupts was smaller than some magic 10 tics.

If no one is working on this already, please let me know and I will
clean this timestamping mess up.

Cheers,

Thomas

On Mon, Feb 9, 2009 at 3:13 AM, Omprakash Gnawali <gnawali at usc.edu> wrote:
> On Mon, Feb 9, 2009 at 2:09 AM, Andreas Köpke <koepke at tkn.tu-berlin.de> wrote:
>>> Branislav Kusy wrote:
>>> > so it seems the problem fixed?
>>> >
>> Ok -- I did some more measurements with the code, so the patch in
>> CC2420TransmitP works well: now all timesync packets are transmitted with a
>> correct timesync field.
>>
>> But on the CC2420ReceiveP side, all timestamps are cleared again. The CVS
>> version 1.17 works fine for me, but the 1.18 does not.
>>
>> And while we are at it: can we remove this time stamp queue stuff? I can not
>> imagine how this should work with LPL.
>>
>
> In one experiment, getGlobalTime call returned a success but the time
> was all over the place; it should have been roughly linear over time.
> This happened for a significant fraction of the experiment duration.
> In another run, this was not the case.
>
> - om_p
>
> _______________________________________________
> Tinyos-devel mailing list
> Tinyos-devel at millennium.berkeley.edu
> https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-devel
>



-- 
"Don't complain; Just work harder" - Randy Pausch

Thomas Schmid, Ph.D. Candidate
Networked & Embedded Systems Laboratory (NESL)
University of California, Los Angeles (UCLA)