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Re: [avr-gcc-list] My first time with AVR (help)


From: Erik Christiansen
Subject: Re: [avr-gcc-list] My first time with AVR (help)
Date: Mon, 19 Jan 2004 11:08:39 +1100
User-agent: Mutt/1.3.28i

On Sun, Jan 18, 2004 at 07:26:05PM +0100, Helix wrote:
> Okay, I put the scope on pin 14, 15 of my 8515 (XTAL1 XTAL2)
> And I'm unable to see any clock
> My XTAL is a 7.378Mhz with two 22n capacitors connected to GND

Helix,

   Hopefully you mean 22 pF, not 22 nF, as stated. Capacitors 1000 times
too large will chop the loop gain so low that oscillation is not
possible at high frequency.

   XTAL2 is the oscillator output, and will have the larger signal.
Measure from XTAL2 to ground. At 7.378Mhz, you should not need to
program the CKOPT fuse, as we had to on the ATmega64, to make the
oscillator start with a 16 MHz crystal. (But you can try the extra
drive, just for fun.)

Good luck,
Erik


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