AVR-Chat

check the datasheet, it does the same (compansation tricks).
 
 
 
Regards
 
Murat Karadeniz
http://www.onlinefavbar.com/mukas

-----Original Message-----
From: AVR-Chat@yahoogroups.com [mailto:AVR-Chat@yahoogroups.com] On
Behalf Of Chad O'Neill
Sent: Monday, December 12, 2005 9:47 PM
To: AVR-Chat@yahoogroups.com
Subject: Re: [AVR-Chat] RTC on Mega 8


How accurate are devices like the DS1302Z?

Chad

MuRaT KaRaDeNiZ wrote: 


Well, you can try using a temperature measuring device in a pulsed
manner and compansate for the thermal deviations and other offsets in
software, connect atmega device to pc, use online atomic time servers to
get accurate reference clock. can be a nice challange :)
 
 
Regards
 
Murat Karadeniz
http://www.onlinefavbar.com/mukas
 
 
 
   -----Original Message-----
From: AVR-Chat@yahoogroups.com [mailto:AVR-Chat@yahoogroups.com] On
Behalf Of Chad O'Neill
Sent: Monday, December 12, 2005 9:30 PM
To: AVR-Chat@yahoogroups.com
Subject: Re: [AVR-Chat] RTC on Mega 8



What would you recommend then if you wanted the accuracy of a normal
digital watch?

Chad O'Neill

Ralph Hilton wrote: 

On Mon, 12 Dec 2005 15:12:52 +1030 you wrote:



  

Hi All,



I'm trying to get a RTC going on a Mega 8 using a 32 kc watch crystal

as per Atmel app note AVR134.



The code works well except that the time gains about 3 seconds per hour.



The crystal is a surplus watch crystal  that I had and I have no idea of


the capacitance

load that it requires.



Anyone on the list used a watch crystal on an avr and how accurate can 

you make them for

time keeping ?



Do I need a 6pf or 10pf crystal?



Do I need any extra caps to gnd, not using any at the moment, would a 

small trimmer help?

    



I would enable the CKOPT fuse which makes added capacitors unnecessary.

I would expect a few seconds a day error from a new crystal.

If you want something more accurate maxim give away free samples of the
DS32KHz oscillator

which is good to about a second a week. 

--

Ralph Hilton

http://www.ralphhilton.org

C-Meter: http://www.cmeter.org

FZAOINT http://www.fzaoint.net








 

Yahoo! Groups Links



    http://groups.yahoo.com/group/AVR-Chat/



    AVR-Chat-unsubscribe@yahoogroups.com



    http://docs.yahoo.com/info/terms/

 













  


  _____  

YAHOO! GROUPS LINKS 


	
*	 Visit your group "AVR-Chat
<http://groups.yahoo.com/group/AVR-Chat> " on the web.
  

*	 To unsubscribe from this group, send an email to:
 AVR-Chat-unsubscribe@yahoogroups.com
<mailto:AVR-Chat-unsubscribe@yahoogroups.com?subject=Unsubscribe> 
  

*	 Your use of Yahoo! Groups is subject to the Yahoo! Terms of
Service <http://docs.yahoo.com/info/terms/> . 


  _____