[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

[avr-chat] Re: weak crystal driving mode

From: Clemens Koller
Subject: [avr-chat] Re: weak crystal driving mode
Date: Fri, 30 Nov 2007 11:39:43 +0100
User-agent: Thunderbird (Windows/20071031)

David VanHorn wrote:
Check your CKOPT fuse. You should not run with that fuse in the
default state without a lot of research as to wether your crystal will
work on that drive.
As I said, I verified that it works reliable, so I can recommend
using that feature _if_done_right_ to save power, since the
internal oscillator isn't really precise, even if calibrated
(and it still depends on temperature).

Yeah, that's what we thought too. Unfortunately, with standard
crystals, it's a major disaster.

Yes, you might fail with the cheap HC49 standard stuff.

IF you have a crystal designed for working in this mode, then it
works. No argument there.
Atmel USA was not able to refer me to any part number that they
thought would work, and were unable to tell me how to qualify a
crystal for that mode.

Yes, because then they would have been responsible for that...

> In fact, they asked me to point them to anything that I found on those lines.

That's poor. IMO it's not really magic. You can even simulate
the oscillator and checkout driving powers with swings to several 100mVs.

I've chosen a typical low "drive level", low voltage AT-cut crystal
(i.e. 25uWatts typ.) in fundamental mode. But no, I cannot
recommend any crystal for use in the low-drive mode. :-P

Unfortuntely only available in german, but still very good:
"Das Quarzkochbuch"


Clemens Koller
R&D Imaging Devices
Anagramm GmbH
Rupert-Mayer-Straße 45/1
Linhof Werksgelände
D-81379 München
Fax 089-741518-19

reply via email to

[Prev in Thread] Current Thread [Next in Thread]