[Tinyos-help] start frame delimiter (SFD) detection - time precision

[roberto pagliari]

sure, the flag CC2420_STATUS_TX_ACTIVE returned by the radiochip, when
STXON_CCA is called, is set if the radio started the transmission. Using
just the command strobe STXON the transmission starts, no matter which value
the cca is.

On 6/30/07, Mehedi Bakht <mbakht at gmail.com> wrote:
>
> Hi,
>
> I don't know about the receive part. But if you want to know when the
> transmission begins in a tmote (or any other mote that uses CC2420 in TinyOS
> 2.x)  you might have a look at the file CC2420TransmitP.nc. In the
> function attemptSend(), there is a line like the following:
>
> status = m_cca ? call STXONCCA.strobe() : call STXON.strobe();
>
> Then there is a line again:
>
> if ( status & CC2420_STATUS_TX_ACTIVE )
>     congestion = FALSE;
>
> My understanding  (I might be wrong) is that if the second condition is
> true ( i.e., congestion = FALSE), then the first line (the call to strobe)
> actually started the transmission.
>
>
> --Mehedi
>
>
> On 6/30/07, ps.box at clix.pt <ps.box at clix.pt> wrote:
> >
> > Hi Mehedi, thanks for the answer.  I've made a LocalTimeMicro component
> > with those components you said, but now how can I make sure I get the time
> > of arrival of the packet? If I place  the "call LocalTimeMicro.get ()"
> > in the Receive.receive/Send.sendDone() event, some (or many)
> > microseconds have passed since the actual arrival/departure of the packet
> > (the SFD detection). What I would like is that the packet's time metadata
> > was in microseconds
> >
> >
> >
> > On Fri Jun 29 23:58 , 'Mehedi Bakht' <mbakht at gmail.com> wrote:
> >
> > You might use a microsecond counter (MSP430CounterMicroC if you are
> > working on MSP430 platform) and then wire it CounterToLocalTimeC to get the
> > current time. You will have to use TransformCounterC component to convert
> > the 16-bit values to 32-bit values.
> >
> > Hope it helps.
> >
> > --Mehedi
> >
> > On 6/29/07, ps.box at clix.pt <ps.box at clix.pt > wrote:
> > >
> > >
> > > Hello tinyos-ers!
> > >
> > > I'm using the "time" metadata field to know when the packet was
> > > received/sent, but that is in 32khz time units. Is there any way to know the
> > > time in microseconds? And possibly in a larger integer than 16bit?
> > >
> > >
> > > Hope to hear from you,
> > >
> > > thanks in advance
> > >
> > >
> > >
> > >
> > >
> >
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