[Coco] Clock chips

[Steve]

The loosing of time with DS1307 is never do to the DS1307 chip itself, 
but the Crystal connected to it.  A new crystal with more accuracy will 
home it to only off by a second or two a day.

In one project, the DS1307 was off by a bit under 1 second a day. So, I 
added code that on Sunday at midnight would added 6 seconds.  This 
standard alone computer is only off by 1 second a month.  This is 
important since this computer is the Church's Bell Tower system and the 
chimes must be on time.

While I do check the time on the computer a few times a months, I don't 
need to adjusted it more than once or twice a year.

The program also adjust for U.S. Daylight saving time so I don't have to 
show up on those Sundays when the U.S. time shifts.

By the way, Crystal can lose their accuracy of time.  If they're older 
than a decade, it maybe time to replace them.  With yours loosing 120 
seconds in 24 hours, it times to replace the crystal.

The PDF states this about the Crystal...

/Connections for Standard 32.768kHz Quartz Crystal. The internal 
oscillator circuitry is designed for operation with a crystal having a 
specified load capacitance (CL) of 12.5pF./

Jameco price for a new Crystal is only $0.49 with the Frequency 
Tolerance at +/- 50 PPM or about 0.00254% off.  But even with that 
accuracy, it will off by up to 2 seconds a day.  The problem is the min. 
shipping cost.  It's high at $4.00 to $7.00 in the U.S.

the 
link:http://www.jameco.com/webapp/wcs/stores/servlet/Product_10001_10001_325244_-1

Over at taydaelectronics.com they have it for just $.011 with a 
Frequency Tolerance at +/- 20 PPM or about 0.0001% off or less than a 
seconds a day.  While they are in THAILAND, the prices are low and the 
shipping is not too bad. This part (1 or 10 of them) only had $1.00 for 
standard rate U.S. shipping.  It may take week to 10 days for the lowest 
price shipping, but they are cheaper than any U.S. parts house I've found.

The Link: 
http://www.taydaelectronics.com/32-768-khz-crystal-cylender-3-x-8-mm.html

I've been selling a number of "kits" and found taydaelectronics.com a 
good source for small electronic parts. Not one problem in the eight 
months that I've been using them.

Steve


On 12/20/2013 12:19 PM, Mark Marlette wrote:
> Brian,
>
> Currently my projects have a DS1307 in them.
>
> **Might** remove  and go with a software RTC, it looses time at about 1min per 12hrs. That is terrible of course.
>
> I do have SNTP client taking care of that issue though.... yep on a CoCo. :)
>
> You can have four different time servers in a config file on the SD, refresh and retry intervals definable as well.
>
> The DS1307 is cheap enough that I'll probable leave it in, in case an Internet connection is not available for a good period of time.
>
> Also have SMTP, NO-IP Update client and Web Server as well all in 24K of code. :)
>
>
> Been spending my time on the development of this firmware...need to get back to the other projects......
>
> Regards,
>
> Mark
> http://www.cloud9tech.com
>
>
>
> ________________________________
>   From: Brian Goers <briang0671 at sbcglobal.net>
> To: CoCoList for Color Computer Enthusiasts <coco at maltedmedia.com>
> Sent: Friday, December 20, 2013 1:50 PM
> Subject: [Coco] Clock chips
>   
>
> If I was to thinking out loud?
> What clocks chip could we putin our system?
> Not cause errors in our systemsand not be difficult to install.
> Can it be placed in any Color Computer 1, 2 or 3?
>