[Tinyos-help] CRC in CC2420

[Jordi Pérez]

Hi!

I have just tried it, and it works correctly. I see the bad and the correct
packets.

Thanks a lot ;-)

Jordi



2009/2/17 Razvan Musaloiu-E. <razvanm at cs.jhu.edu>

> Hi!
>
> On Mon, 16 Feb 2009, Jordi Pérez wrote:
>
>  Hi Razvan!
>>
>> I tryed to understand the code to disable the filtering you said, but I
>> can't. Do you mind explaining me the things I have to change?
>>
>> In RXFIFO.readDone event when I modify something, the program doesn't
>> work.
>> So I don't know how disable it.
>>
>> In the SubReceive.receive event I changed the word Snoop to Receive, but I
>> don't really know if it is correct.
>>
>> Can you help me please?
>>
>
> I attached a patch that takes out the parts that discards the packets with
> bad CRC. It's against the latest CVS and you can apply it with this requence
> of commands:
>        cd $TOSROOT
>        patch -p1 < cc2420-ignore-crc-patch.diff
>
> Warning: I didn't have time to test this! I only made sure that it compiles
> fine. :-) Give it a try and if it doesn't work at it should I'll look more
> into it.
>
> --
> Razvan ME
>
>
>  2009/2/12 Razvan Musaloiu-E. <razvanm at cs.jhu.edu>
>>
>>  Hi!
>>>
>>>
>>> On Wed, 11 Feb 2009, Jordi Pérez wrote:
>>>
>>>  Dear all,
>>>
>>>>
>>>> For CC2420, if AUTOCRC is set, will the hardware reject CRC-error packet
>>>> automatically?
>>>> If true, then is it possible to receive those packets but with AUTOCRC
>>>> still
>>>> being set? I want to receive this packets and rebuild them.
>>>>
>>>>
>>>>  The CC2420 is not discarding the packets with bad CRC. What does is to
>>> indicate using a bit that the packet was bad (page 38, section 16.4 from
>>> [1]). The TinyOS driver for CC2420 inspects this bit and discards the
>>> packets if that bit is not 1. You can see this happening in the
>>> RXFIFO.readDone event from CC2420ReceiveP.nc. The switch branch of
>>> interest
>>> is 'case S_RX_PAYLOAD:'.
>>>
>>> The other filtering that you'll have to disable is in the
>>> SubReceive.receive event from CC2420ActiveMessageP.nc.
>>>
>>> [1] http://focus.ti.com/lit/ds/symlink/cc2420.pdf
>>>
>>> --
>>> Razvan ME
>>>
>>
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