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Re: [avr-chat] avrdude-ATMega32 fuse bits issues
From: |
Brian Dean |
Subject: |
Re: [avr-chat] avrdude-ATMega32 fuse bits issues |
Date: |
Wed, 21 Dec 2005 15:54:50 -0500 |
User-agent: |
Mutt/1.5.11 |
On Wed, Dec 21, 2005 at 09:58:34AM -0500, Graham Davies wrote:
> In a post on November 12, I described an experiment in which an
> ATmega16-16PC ran with a 15.36 MHz crystal with a wide variety of
> fuse setting, including CKOPT not programmed. The experiment
> included long traces and lots of stray capacitance at the crystal
> pins and I later extended it to include a large imbalance in the
> load capacitors. It always worked. So, it seems to me that the
> crystal circuit is not really so sensitive. I withhold an opinion
> about those plug-in breadboards, though. I would not use one
> myself.
No offense, but your experiment is just one data point. Contrary to
your experiment, I've had problems with the oscillator starting when
CKOPT is unprogrammed using a 16 MHz crystal. Simply program CKOPT
and it works fine, so I guess my experience contradicts yours - I used
an ATmega128, perhaps it is more sensitive to this than the ATmega16,
maybe it was just that particular batch of chips, I don't know.
Anyway, the datasheet also says CKOPT should be programmed for these
higher speed settings. So when people have trouble with the
oscillator when using a 16 MHz crystal or resonator, and they are not
following the recommendations of the datasheet, the first thing they
should do is get in-line with the datasheet recommendations and verify
that CKOPT is programmed. This is just standard checklist stuff when
troubleshooting.
-Brian
--
Brian Dean
ATmega128 based MAVRIC controllers
http://www.bdmicro.com/
- [avr-chat] avrdude-ATMega32 fuse bits issues, Chris Pontiga, 2005/12/18
- Re: [avr-chat] avrdude-ATMega32 fuse bits issues, Brian Dean, 2005/12/20
- Re: [avr-chat] avrdude-ATMega32 fuse bits issues, Chris Pontiga, 2005/12/20
- Re: [avr-chat] avrdude-ATMega32 fuse bits issues, Graham Davies, 2005/12/21
- Re: [avr-chat] avrdude-ATMega32 fuse bits issues,
Brian Dean <=
- Re: [avr-chat] avrdude-ATMega32 fuse bits issues, Graham Davies, 2005/12/21
- Re: [avr-chat] avrdude-ATMega32 fuse bits issues, Richard Urwin, 2005/12/21
- CKOPT (was Re: [avr-chat] avrdude-ATMega32 fuse bits issues), Graham Davies, 2005/12/21
- Re: CKOPT (was Re: [avr-chat] avrdude-ATMega32 fuse bits issues), Richard Urwin, 2005/12/22
- Re: CKOPT (was Re: [avr-chat] avrdude-ATMega32 fuse bits issues), Daniel O'Connor, 2005/12/22
Re: [avr-chat] avrdude-ATMega32 fuse bits issues, Neil Davey, 2005/12/21