l think l'd rely on a sync pulse rather than internal startup because l know
for a fact they dont always sync...xtals may not always start the same time
either...

chip 1: pause say 1ms
chip 1: one cycle to set a bit
            allow for error 1 cycle of chip2 loop
            go

chip2: pause 500us
            go into detect loop
chip 2: detect sync bit (would need loop so say about 3
                                        cycles)
            go

sounds good in theory anyway...


----- Original Message -----
From: "Oliver Broad" <obroad@TELINCO.CO.UK>
To: <PICLIST@MITVMA.MIT.EDU>
Sent: Monday, September 25, 2000 12:34 AM
Subject: Re: [PIC]: Synchronizing two PICs


> I get the impression that holding MCLR low for longer than the worst case
> startup time will synchronise PICs, assuming I read the explanation right
> (long time ago) the osc runs and the startup timer counts all the time
MCLR
> is low, so I presume with an ext clock it could be done. MCLR might have
to
> be synchronised to the clock to prevent an occasional race condition that
> would introduce 1 cycle uncertainty.
>
> Otherwise I guess the generic (any deterministic micro) solution is to
have
> a loop that generates pulses until an 'OK' signal is returned by external
> logic. The logic could suppress clock pulses to one PIC until they are in
> step, then signal OK. A single edge might be enough?
>
> Throws open the challenge: What's the least logic needed to do this?
>
> Oliver.
>
> ----- Original Message -----
> From: Dan Michaels <oricom@LYNX.SNI.NET>
> To: <PICLIST@MITVMA.MIT.EDU>
> Sent: Friday, September 22, 2000 8:32 PM
> Subject: Re: [PIC]: Synchronizing two PICs
>
>
> > Adam Davis wrote:
> > >Ok, I understand this subject has been hashed before, but I've not seen
> any
> > >follow ups...  (see the 6/24/99 Thread "Dual pics, one xtal?")
> > >
> > >Can one reset two PICs such that they come up in the same state?  I'm
> > interested
> > >in real-world tests.
> > >
> > ..........
> > >
> >
> >
> > Interestingly, I have a project where I was wanting to do something
> > similar in running up to 6 scenix SX28s - in cycle sync - off a common
> > oscillator chip. So, anyone tried that [after first answering about
> > PICs, of course]?
> >
> > --
> > http://www.piclist.com#nomail Going offline? Don't AutoReply us!
> > use mailto:listserv@mitvma.mit.edu?body=SET%20PICList%20DIGEST
> >
> >
> >
>
> --
> http://www.piclist.com hint: PICList Posts must start with ONE topic:
> "[PIC]:" PIC only "[EE]:" engineering "[OT]:" off topic "[AD]:" ad's
>
>

--
http://www.piclist.com hint: PICList Posts must start with ONE topic:
"[PIC]:" PIC only "[EE]:" engineering "[OT]:" off topic "[AD]:" ad's