2 pic 1 quartz

denis_11 · Joined: 13 Jul 2010 Posts: 45

Hello I connect two 12f683 to a single crystal... I have to generate two different pw... say that it works?

Franck26 · Joined: 29 Dec 2007 Posts: 122 Location: Ireland

Hi,
I don't understand what you are trying to do, but it sound crazy!!!

You cannot connect your quartz to 2 micro as it's done on your schematic.

Good luck
Franck.

PCM programmer · Joined: 06 Sep 2003 Posts: 21708

Actually there are many threads on this in the Microchip forum:
http://www.microchip.com/forums/m373427.aspx
http://www.microchip.com/forums/m482855.aspx

Humberto · Posted: Sun Jul 18, 2010 1:38 pm

Yes you can. Connecting OSC2 from the U1 to OSC1 of U2 as shown the schematic it is perfectly legal.
Be aware that if you are driving more than -let says- 2 or 3 PICs, you will need a CMOS or TTL driver/buffer
with a bigger fan out than OSC2.

You have to set Oscillator setup (#FUSES) accordingly in each PIC.
For U1

denis_11 · Joined: 13 Jul 2010 Posts: 45

Franck26 · Joined: 29 Dec 2007 Posts: 122 Location: Ireland

If I answer only when I'm 100% sure, I would never answer.
At least I made you laugh!!!

You can have a look at the post #12 of this link:
http://www.microchip.com/forums/m482855.aspx

I would add that the clock input pin of the second micro is going to add some capacitance to 1 side of the quartz, which can prevent the oscillation from starting.

This is not something that I would use for a professional circuit, except of course if there is a microchip AN on this topic (and maybe there is).

Franck.