Thanks for the link!

I had just cobbled up my own decode routine, but I didn't tackle using the bit
stream to sync the rate.

I just use a 'standard' bit banged serial routine to wait for a sync byte after
'1' '0' balanced preamble bytes.  Then I decode the buffer.

I hope you find your routine (and post it ;-).

If anyone is interested in an ugly, fat, second pic project, manchester decode
routine:

decode
        ; data starts off stored in temp (rxreg is also used)
        movlw   0x00            ; start with all 0
        movwf   rxreg           ; temp space for holding output
        bcf     STATUS, C       ; make sure carry is cleared
        btfsc   temp, 7         ; check bit
        bsf     STATUS, C       ; if set, shift 1 into dest byte
        rlf     rxreg, F
        bcf     STATUS, C       ; make sure carry is cleared
        btfsc   temp, 5
        bsf     STATUS, C
        rlf     rxreg, F
        bcf     STATUS, C       ; make sure carry is cleared
        btfsc   temp,3
        bsf     STATUS, C
        rlf     rxreg, F
        bcf     STATUS, C       ; make sure carry is cleared
        btfsc   temp,1
        bsf     STATUS, C
        rlf     rxreg, W        ; store in W for last bit

        return


Les Otter wrote:
>
> Well, if anyone else is interested, I have found the most useful decoding routines
> yet..
> http://www.microchip.com/download/appnote/keeloq/91045a.pdf
> It's the "KEELOQ MAnchester Encoding Routines" TB045 document.
> Still searching for others....
>
> Les
>
> > -----Original Message-----
> > From: James Newton. Admin 3 [mailto:jamesnewton@piclist.com]
> > Sent: 20 February 2002 01:55
> > To: LesOtter@saurel.demon.co.uk
> > Subject: RE: [PIC]:Manchester encoding/decoding routine examples please
> >
> >
> > Oops! Good point. There is some discussion in the archive at
> > http://www.piclist.com/techref/postbot.asp?by=time&id=piclist/1998/03/06/183
> > 030a
> > and
> > http://www.piclist.com/techref/postbot.asp?by=time&id=piclist/2001/01/02/164
> > 503a
> >
> > But no code. I looked at rocketaware.com and the US Patent office and
> > without much success... you might look through the results for Manchester
> > and decode and preamble at the patent office:
> > http://patft.uspto.gov/netacgi/nph-Parser?Sect1=PTO2&Sect2=HITOFF&u=%2Fnetah
> > tml%2Fsearch-adv.htm&r=0&p=1&f=S&l=50&Query=manchester+and+decode+and+preamb
> > le&d=ft00
> >
> > Please consider sharing what you find.
> >
> > ---
> > James Newton, webmaster piclist.com (former Admin #3)
> > mailto:jamesnewton@piclist.com
> > 1-619-652-0593 VM 1-208-279-8767 FAX
> > PIC/PICList FAQ: http://www.piclist.com or .org
> >
> >
> >
> > -----Original Message-----
> > From: Les Otter [mailto:LesOtter@saurel.demon.co.uk]
> > Sent: Tuesday, February 19, 2002 15:55
> > To: jamesnewton@piclist.com
> > Subject: RE: [PIC]:Manchester encoding/decoding routine examples please
> > Importance: Low
> >
> >
> > James
> > Thanks for that, but that's just a code snippet for encoding..not a codec.
> > I am now up to speed on what bit translation goes on at each end, but the
> > ancoding and decoding of a packet is what I am interested in.
> >
> > I am still trying to figure out how best to process a preamble header stream
> > to sync the bit time to (thereby catering for various bps rates), and adjust
> > the sample timer as reception proceeds to account for frequency drift.
> >
> > I would like to send, say a 32 bit preamble (16 1-0 or 0-1 pairs), followed
> > by a header block of say 4 bytes (of 0-0 pairs) - which would signify the
> > start of actual data.
> >
> > Then receive (in Manchester format of course!) two bytes which signifiy the
> > length of data packet.  Then process the bitstream, adjusting the clock as
> > we go.
> >
> > I think the KEELOQ encoders send a similar pattern, but without the variable
> > data packet bytes.
> >
> > Rgds
> > Les
> >
> > > -----Original Message-----
> > > From: pic microcontroller discussion list
> > > [mailto:PICLIST@MITVMA.MIT.EDU]On Behalf Of James Newton. Admin 3
> > > Sent: 19 February 2002 23:12
> > > To: PICLIST@MITVMA.MIT.EDU
> > > Subject: Re: [PIC]:Manchester encoding/decoding routine examples please
> > >
> > >
> > > source= http://www.piclist.com/postbot.asp?id=piclist\2002\02\19\071218a
> > >
> > > Manchester codec for PIC's in the FAQ at
> > > http://www.piclist.com/techref/microchip/manchester.htm
> > >
> > > ---
> > > James Newton: PICList.com webmaster, former Admin #3
> > > mailto:jamesnewton@piclist.com  1-619-652-0593 phone
> > > http://www.piclist.com/member/JMN-EFP-786
> > > PIC/PICList FAQ: http://www.piclist.com
> > >
> > > --
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> > >
> > >
> >
> >
>
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