[Tinyos-help] cc2420 LPL broadcasting

[Flavio Pompermaier]

I noticed that, but this recalibration seems to happen also after
receiving/listening..isn'it? Can I consider it as a tx<->rx transition?
Just some minute ago I noticed that the 3 phase last about 840 us..what is
that? Is the tx->rx transition (840us) longer than the rx->tx one (140 us)?
And phase 4? What does it represent? Is it the backoff? My estimations for
min-max values are correct..?


--- Gio 28/8/08, Sarfraz Nawaz <sarfraz at gmail.com> ha scritto:

> Da: Sarfraz Nawaz <sarfraz at gmail.com>
> Oggetto: Re: [Tinyos-help] cc2420 LPL broadcasting
> A: fla83tnn at yahoo.it
> Cc: "Tinyos" <tinyos-help at millennium.berkeley.edu>
> Data: Giovedì 28 agosto 2008, 16:44
> There is a state diagram on page 45 of cc2420 datasheet
> which might be
> helpful. After the transmission is complete, it goes into a
> state
> where the oscillator is calibrated again.
> 
> On Thu, Aug 28, 2008 at 8:13 PM, Flavio Pompermaier
> <fla83tnn at yahoo.it> wrote:
> > cc2420 broadcast transmission has a periodic waveform
> like this (leaving out non-periodic phases such as radio
> initialization or DELAY_AFTER_RECEIVE listening):
> >
> >     2  3    4   5
> >    | |   |____|  |
> >  1  | |  /|    |\ |  1  ....
> > ____| | / |    | \|____
> >    |\|/  |    |
> >    | |   |    |   | |
> >
> > If I understood correctly and supposing that the
> message to broadcast is 24 bytes long (i.e., 24+11 (MAC
> header)+2 (CRC)-->37 bytes-->74 symbols. Being 2
> symbols sent in 1 jiffy then the tx of the message should
> theoretically take 1.13 ms):
> >
> > 1) is the transmission of the message (oscilloscope
> duration: 1.4 ms. Almost equal to the expected value)
> > 2) After transmission cc2420 drops its current
> consumption for 140 us.
> > Probably it corresponds to the tx/rx transition. Am I
> right?
> > 3 and 4)Total duration is about 2.120 ms. What do they
> represent? Are they backoff + cca???
> > 5) 140 us. Probably it corresponds to the rx/tx
> transition.
> >
> > Am I correct? If so, can I consider tx<->rx 
> transition to last 140 us?
> > And what represent phases 3 and 4? And what is the
> backoff range (in ms)?
> > Is it correct to consider min backoff = 10 jiffies and
> max 50 jiffies (min 0.305 ms and max  1.5 ms)? And waht is
> the duration of CCA?
> >
> > Best regards,
> > FP
> >
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