[Tinyos-devel] timestamps in seriallisten/sflisten etc.

[Vlado Handziski]

On Fri, Jun 27, 2008 at 00:08, Philip Levis <pal at cs.stanford.edu> wrote:

> On Jun 26, 2008, at 3:00 PM, Vlado Handziski wrote:
>
>
>> Because  I actually want that timestamp to represent the time the packet
>> was sent on the mote side and not when it was received by the PC side. I
>> want a packet fromat that will allow the mote to insert a stamp before
>> sending it to the PC. The PC checks the type and corrects the stamp
>> translating it into local representation of the time it was sent by the
>> mote. The delay over the serial line + the usb_to_serial driver, etc.,
>> especially in cases like in our testbed where we have chais of active USB
>> cables, hubs with up to 8 devices, etc. is non negligible.  Once this very
>> variable delay is factored out, plain old NTP sync over a set of distribited
>> SFs hosts is enough to achieve precision allowing one to track causality
>> relationships between the events received on the different SFs, without
>> using any time sync protocol on the mote side.
>>
>
> OK. Can we agree that these are two separate issues? Having a packet format
> which embeds mote timestamps is independent of whether the toolchain adds
> local timestamps.
>
>
Yes, they are different. But for me an integrated PC side source stamp is
not a lot more useful than issuing a stamp in the printing/logging stage.

Vlado
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