>>For stability, you can either use a buffer, or, better yet, use
>>a separate crystal oscillator and drive all PICs from the same source

yes I was thingking about that but I need to run the PIC18 at 40MHZ using a 
10MHZcrystal times 4PLL in the data sheet you do that in HS+PLL mode.. can 
the PIC be run in EC mode using a 40MHZ crystal directly instead.. as ther 
is nothing said about it in the datasheets all refference I could find 
highiest is about 20MHZ..
thanks...

----- Original Message ----- 
From: "Sergey A.Dryga" <sdryga@nc.rr.com>
Newsgroups: gmane.comp.hardware.microcontrollers.pic
Sent: Tuesday, September 19, 2006 4:42 PM
Subject: Re: [PIC]Driving Several PIC's with one crystal.


> genome <jtroxas <at> gmail.com> writes:
>
>>
>> hello..
>> Is it possible to drive 2 or 3 PIC's with only one crystal in HS+PLL mode 
>> to
>> operate them on the same frequency.. If so.. how may one do this?.
>>
>> I read somewhere in some microchip appnotes... if I remember... that 
>> there
>> is an inverting amplifier inside the pic that causes the crystal to 
>> oscilate
>> the output of that amp is in osc2.. and input on osc1, something to do 
>> wth
>> the amp producing a 180degrees phase shift.. maybe somebody could explain
>> it.. this is why I'm having trouble the amp in the PIC is part of the
>> oscilator not just the crystal... is this correct??????
>>
>
> The datasheet, at least for the 16F877A confirms what you are saying.  You 
> can
> provide clock signal to osc1 input only and leave osc2 open.  I am not 
> sure
> that adding more PICs to the osc2 output of another will work because you 
> might
> overload osc2.  For stability, you can either use a buffer, or, better 
> yet, use
> a separate crystal oscillator and drive all PICs from the same source.
>
> Sergey Dryga
> http://beaglerobotics.com
>
>
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