[Tinyos-help] CC2420: length field in 802.15.4 header is used without initialisation, fcf field not set in any case

Stephen Dawson-Haggerty stevedh at eecs.berkeley.edu
Fri Nov 5 22:40:53 PDT 2010


Yes, you are correct.  Thanks for suggesting the changes -- can you
check out 5215 and verify that this fixes the problem?

Thanks,
Steve

On Thu, Nov 4, 2010 at 9:34 PM, Silvan Nellen <Nellen at cmc.ca> wrote:
> Hello,
>
>
>
> I have two issues regarding revision 5214 (the newest at the time of
> writing) of the trunk (https://tinyos-main.googlecode.com/svn/trunk):
>
>
>
> 1.
>
> After updating from revision 5160 to 5214, Zigbee communication stopped
> working on Shimmer. Using a Zigbee packet sniffer I found out that all
> updated nodes send packets with the length field of the header set to an
> invalid value. After looking at the source code of the CC2420 driver
> (Shimmer uses CC2420) I found the reason why: the code that sets the length
> field in the header had been commented out
> (/trunk/tos/chips/cc2420/csma/CC2420CsmaP.nc, line 136)! The change was
> introduced in r5174.
>
>
>
> Am I missing something or is this a serious bug that needs to be fixed ?
>
>
>
> 2.
>
> Another CC2420 related issue is that the fcf field in the header is not set
> in some cases. In the current version of the trunk the fcf field is set in
> the RadioResource.granted() event handler in
> /trunk/tos/chips/cc2420/csma/CC2420ActiveMessageP.nc. However this event is
> not triggered if access to the radio is granted immediately (line 104), in
> this case fcf remains uninitialized!
>
>
>
> Why was the initialization fcf code moved from the Send.send() command in
> tos/chips/cc2420/csma/CC2420CsmaP.nc to RadioResource.granted() ? What would
> be the cleanest way to fix this ? Move the initialization code back to
> CC2420CsmaP.nc?
>
>
>
> Regards,
>
>  Silvan Nellen
>
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>



-- 
stephen dawson-haggerty
http://cs.berkeley.edu/~stevedh
uc berkeley wireless and embedded systems lab
berkeley, ca 94720



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