[Tinyos-help] Help with Ack' s in CC2420TransmitP.nc

[Razvan Musaloiu-E.]

Hi!

On Fri, 12 Dec 2008, Ramon Duato Navarro wrote:

> Hi!
> Maybe someone can help me. 
> I am working with TinyOs 2.1 and Micaz and want to understand
> the link layer without using Packet Link Layer.
>

The Packet Link is implemented in chips/cc2420/link. The retransmission 
are implemented in PacketLinkP.nc from that place.

I hope this helps. :-)
Razvan ME

> I am reading the CC2420Csma.nc CC2420TransmitP.nc file and I 
>
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>  am getting a bit confused with the ACK's 
>
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> In CC2420TransmitP.nc, when you send a packet and receive an ACK then you call
>
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> signalDone(SUCCESS);
>  
> and the sendDone event is signalled with SUCCESS.
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> But what happens when you don't receive the ACK??
>
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> As far as I have understood, you call 
> call BackoffTimer.start( CC2420_ACK_WAIT_DELAY )
>
>
> and when this Timer expires you call again
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> signalDone(SUCCESS);
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> (since we are in the ACK_WAIT state)
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>
> So , there are no retransmissions and you do the same signalling as if you had received the ACK.
> Is that correct?
> Thanks in advance!
> Ramon.
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