[Tinyos-help] cc2420 LPL broadcasting

[Sarfraz Nawaz]

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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