ugh...I think you're right...
Looks like the radio CRC gets wiped by SpiByteFifo.dataReady()
in CC1000RAdioIntM.nc... look for:
rxbufptr->crc
Although the radio receive only looks at the CRC in order to
implement ACKs correctly and the message is passed along no matter.
Then the CRC gets recalculated for the uart by ByteComm.txByteReady()
in FramerM.nc... look for:
gTxRunningCRC
You could probably hack both of these in order to get the original
radio CRC, but I'm not taking any bets on what else may be afflicted.
MS
RamKishore wrote:
Hi,
Thanks for helping in creating noisy environment.
Regarding CRCs,The CRC values that you were referring to are those over
wired-medium(RS-232 in my case) between mica2 and PC.To elaborate:As
said,TOS base surely doesn't do any CRC check.It receives only correct
CRC packets from bottom layers.Now,it has to transmit this *correct
packet* without any error to PC.So,it frames it's own CRC and transmits
them to PC.At PC,java tool (Packetizer.java) will strip the CRC sent by
TOSbase ( and copy into "readCrc" of
Packetizer.java::readFramedPacket() ) and now calculate its own CRC
("computedCrc" in Packetizer.java::readFramedPacket())
.Then,cross-checks both and if they are same,it will display.This can be
made sure by looking at TOS_msg->crc feild and crc done by java
tool,which will turn out to be different.
Any ideas about dealing with bottom layer files ? Is there any thing
that can be done with these files:(they seem to be doing something with
crc)
1)tos\platform\mica2\CC1000RadioIntM.nc(I doubt something can be done
here)
2) tos\platform\system\CrcFilter
3) tos\platform\CRCPacket.nc.
As a newbie,i dont know perfectly what is going on?
Many Thanks,
Kishore
Michael Schippling wrote:
I'm "fairly sure" that TOSBase doesn't do any received CRC check.
If you look at Packetizer.java::readFramedPacket() you can see
where messages are rejected based on the CRC failure, so this is
probably the place to hack.
I find that jackhammers and banging on pots and pans are good for
creating a noisy environment...sorry. You probably mean noisy RADIO
environment. It might be easier to reduce the signal, rather than
increase the noise. Removing the antenna from one of the motes
or reducing the transmit power could work. Or use a partial faraday
cage around some of the Motes.
MS
RamKishore wrote:
Hi all,
I want to receive the bad packets which failed CRC test.I
am using TOSbase(/tinyos1.x/contrib/xbow/apps) as receiver(mica2),at
916.4Mhz.I scanned mailing lists,but couldn't figure out anything.
More importantly, could anyone tell me few methods of generating
noisy environment.
Many Thanks in advance,
Kishore
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