Hi all.
The issues is the 16-bit timestamp in the received packet somethimes
results incorrect, in that case the time result always less than what
I aspect.
Probably the the timestamp refers to the previous SFD signal.
I tried to compare that timestmap against the time argument of the
RadioTimeStamp.receivedSFD(uint16_t time){ }. When the timestamp is
correct generally they are equal, in the other cases the
RadioTimeStamp result more precise.
Using:
RadioTimeStamp.receivedSFD(uint16_t time){ }
Now the problem is how can I determine to which kind of packet the SFD
event is referred.
Federico
2007/10/30, Miklos Maroti <[EMAIL PROTECTED]>:
> Hi David,
>
> The problem is not that it overflows, but it contains an inccorect
> value. In certain situations there are more packets in the RXFIFO and
> we do not know how to pair up the timestamps made for the SFD and the
> data packets. This is especially problematic if for some reason some
> of those packets get lost or not even get into the RXFIFO.
>
> We should start a discussion on the Timestamping interface. I think it
> should be allowed for the radio stack to say that it could not
> properly timestamp the packet (just a flag) and the time synch apps
> should check for that flag.
>
> Miklos
>
> On 10/30/07, David Moss <[EMAIL PROTECTED]> wrote:
> > I haven't done much work with the timestamps in the CC2420 apart from
> > Jonathan's original implementation, nor have I used it enough to have
> > experienced any type of erratic behavior. Is the issue here that the 16-bit
> > timestamp rolls over to 0 periodically? Would a 32-bit timestamp be better?
> >
> > -David
> >
> >
> > -----Original Message-----
> > From: [EMAIL PROTECTED]
> > [mailto:[EMAIL PROTECTED] On Behalf Of Federico
> > Fiorentin
> > Sent: Tuesday, October 30, 2007 6:39 AM
> > To: tinyos-help@Millennium.Berkeley.EDU
> > Subject: [Tinyos-help] Bug in CC2420 timestamp
> >
> > I'm working on time synchronization with tmote sky motes and TinyOS2.
> >
> > I'm using a poller that sends a PollPacket every X milliseconds and a
> > set of clients that timestamp the arrival time of the PollPacket.
> > I found that the 16 timestamp in the time field of the Metadata are
> > somethimes incorrect ( CC2420Packet.getMetaData(msg)->time ).
> >
> > This affects the 1% of the TimeStamps per mote.
> > I compared the value "timestamp(n) - timestamp(n-1)" of two different motes.
> >
> > Is there any patch or a way to fix it?
> >
> > I appreciate any advice
> > _______________________________________________
> > Tinyos-help mailing list
> > Tinyos-help@Millennium.Berkeley.EDU
> > https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help
> >
> >
> > _______________________________________________
> > Tinyos-devel mailing list
> > [EMAIL PROTECTED]
> > https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-devel
> >
>
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