Hi Silvan,
I think the problem is with the configuration of CC2420 on Shimmer. We
have run into this as well. Can you please two files in your
platforms/shimmer/chips/cc2420 with the ones I have attached and check
if this fixes your problem?
Miklos
On Mon, Nov 22, 2010 at 1:57 AM, Omprakash Gnawali
gnaw...@cs.stanford.edu wrote:
-- Forwarded message --
From: Silvan Nellen nel...@cmc.ca
Date: Mon, Nov 8, 2010 at 7:36 AM
Subject: [Tinyos-help] Software auto acknowledgements break packet
timestamps in the C2420 driver
To: tinyos-help@millennium.berkeley.edu
tinyos-help@millennium.berkeley.edu
Hello,
I’m trying to run the FTSP test application (revision 5215 of
http://tinyos-main.googlecode.com/svn/trunk) as described in
tinyos-2.x/apps/tests/TestFTSP/Ftsp/README.txt on Shimmer. At first
the nodes running TestFtspAppC didn’t seem to respond to the messages
sent out by the beacon mote (java FtspDataLogger reported nothing).
Using a packet sniffer I discovered that the FTSP motes send ACK
packets for each beacon message but they don’t send report messages
(which would then be picked up by the base station and ultimately be
displayed by the FtspDataLogger).
I looked at the CC2420 driver source code in
tos/chips/cc2420/receive/CC2420ReceiveP.nc and used printf to see
what’s going on, and I think I found the problem: the outgoing ACK
messages trigger the SFD interrupt and cause a timestamp to be put in
to the timestamp queue (line 190). If this happens BEFORE the
timestamp of the incoming packet is read, the packet timestamp is
cleared and the timestamp queue gets flushed (lines 633-635).
Consequently all packets received by the FTSP test application contain
invalid timestamps and are thus ignored (line 67 in TestFtsp.nc).
Does that make sense? Is this a known problem? Has FTSP ever been
tested with CC2420?
As a temporary fix I added PFLAGS += -DCC2420_NO_ACKNOWLEDGEMENTS to
the Makefile and I get messages from the FTSP motes now, however this
fix doesn’t really address the cause of the problem…
Silvan
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HplCC2420InterruptsC.nc
Description: Cdf file
HplCC2420InterruptsP.nc
Description: Cdf file
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