When we were calculating the CRC algorithm using LabVIEW, we did the
following:
1. create the message packet including everything but the Sync bytes (7E)
2. escape the bytes corresponding to 7D, or 7E
3. run the CRC algorithm on the escaped data packet
4. attach the CRC in little endian format (lower byte first)
5. attach the sync bytes
6. Send.
I hope I got that right.
Sankar.
----- Original Message -----
From: "Michael Schippling" <[EMAIL PROTECTED]>
To: "jurin dan" <[EMAIL PROTECTED]>
Cc: "tinyos-help@Millennium.Berkeley.EDU"
<tinyos-help@millennium.berkeley.edu>
Sent: Monday, April 09, 2007 12:13 PM
Subject: Re: [Tinyos-help] CRC checking
I thing that's in the octavetech page, but I believe it is all bytes
including header, before escapes are applied.
I'm not sure but I think the pre-amble 7E 4x is not included.
MS
jurin dan wrote:
thanks a lot for your reply.
just one more thing. within the raw data packet, which byte do i use to
compute the CRC.
is it all byte or only TOS_MSG byte.
------------------------------------------------------------------------
> Date: Sun, 8 Apr 2007 17:22:29 -0600
> From: [EMAIL PROTECTED]
> To: [EMAIL PROTECTED]
> CC: tinyos-help@Millennium.Berkeley.EDU
> Subject: Re: [Tinyos-help] CRC checking
>
> This site describes the message format and CRC calculation:
>
http://www.octavetech.com/pubs/TB5-01%20Deciphering%20TinyOS%20Serial%20Packets.pdf
>
> There's also code in TOS (well...duh) and the java tools which
> does the CRC. I know one is called crc.java
>
> MS
>
> jurin dan wrote:
> >
> > hi,
> >
> > i have the raw data packet below receive with xlisten app:
> >
> >
> > *$ xlisten -r -b=mica2 -s=COM4 -t*
> >
> > *xlisten Ver:$Id: xlisten.c,v 1.2 2005/06/21 01:36:06 pipeng Exp $*
> >
> > *Using params: [baud=0x1001] [raw] [timed]*
> >
> > *COM4 input stream opened*
> >
> > *[2007/04/04 10:40:35]*
> >
> >
*7e42ffff007d5d1d840101009101000000007100000031037d5d0230030000000000000000007964
> > [40]*
> >
> >
> > CRC = 0x6479 (last bytes)
> >
> > i woul like to know how i could use the CRC to check the integrity
of
> > the transmitted packet.
> > and which byte of the packet are taking in acount to compute the
CRC.
> >
> > thanx for your help
> >
> >
>
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