[Tinyos-devel] Possible bug in broadcast code of LPL with CC2420

[Jun]

David,

Thank you for your clarification. I need to go over the bit operations
again:).

Jun

On Wed, Apr 30, 2008 at 2:12 PM, David Moss <dmm at rincon.com> wrote:

>  This line of code is setting all bits in the FCF word to 0, except for
> the acknowledgment bit (the key here is &= instead of =).  The
> acknowledgment request bit retains whatever value it was given in layers
> above.
>
>
>
> Thanks for double checking this,
>
>
>
> -David
>
>
>
>
>  ------------------------------
>
> *From:* tinyos-devel-bounces at millennium.berkeley.edu [mailto:
> tinyos-devel-bounces at millennium.berkeley.edu] *On Behalf Of *Jun
> *Sent:* Wednesday, April 30, 2008 11:38 AM
> *To:* TinyOS Development
> *Subject:* [Tinyos-devel] Possible bug in broadcast code of LPL with
> CC2420
>
>
>
> Hi All,
>
> I just noticed some inconsistent code for broadcast in CC2420 radio core
> when LPL is enabled (tos/chips/cc2420).
> Please correct me if I'm wrong.
>
> I first found that ACK is disabled here for a broadcast packet:
> lpl/DefaultLplP.nc
> 487       if(call AMPacket.destination(currentSendMsg) ==
> AM_BROADCAST_ADDR) {
> 488         call PacketAcknowledgements.noAck(currentSendMsg);
>
> Then the underlying layer will overwrite the ACK flag regardless of its
> previous state:
> csma/CC2420CsmaP.nc
> 139     header->fcf &= 1 << IEEE154_FCF_ACK_REQ;
>
> All the above codes are from the latest CVS.
>
> Thank you,
>
> Jun
>
> --
> --
> Mailto: yanjunrockets at gmail.com
>



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Mailto: yanjunrockets at gmail.com
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