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How to use DS12C887

 
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NewSpace



Joined: 23 Sep 2003
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How to use DS12C887
PostPosted: Thu Feb 03, 2005 2:30 am     Reply with quote

Dear Master~!

Hi there?

I used DS1302... But It's have a offset about 1minute / 1 week
If 1 month different about 4minute...
So I wanna DS12C887...
But I don't how to connect wire and Program...
I wanna help App. code...
Thank you~!
_________________
Hello~?

This is South KOREA
My name is Sanghyouk Kim But Call me Nick
Sorry I'm poor English
Ttelmah
Guest







PostPosted: Thu Feb 03, 2005 3:28 am     Reply with quote

The accuracy of the DS1302, is completely down to how good your crystal is (and how accurately it is trimmed). Yes, you can drive the DS12C887, but you will need a lot of pins, and these are not that much more accurate than you are already achieving (the basic 'accuracy', is only about 1minute/month). Choose a crystal which is warranted to a higher accuracy, look carefully at the capacitance round this part of the circuit, and/or trim the oscillator, and the 1302, will beat the 12C887 'hands down'. I have some systems using a crystal oven, with a 1302, and some have drifted less than 1 second, in over a year...
Even without the cost of a crystal oven, with a good crystal, and some care in the layout, 30 seconds/year, is fairly typical for the 1302. You are trying to use a 'sledgehammer to crack a nut', and won't get much better results than you are already achieving...

Best Wishes
Guest








Try this
PostPosted: Thu Feb 03, 2005 5:11 am     Reply with quote

Ttelmah is corrrect.

For a reasonable accuracy try the Dallas DS32KHz temperature compensated 32KHz oscillator with the DS1302 .

In temperature range 0°C to 40°C the DS32KHz and DS1302 will do better than 2.5 seconds per week, and if you keep it at room temperature (20-25°C) then it will do better than that.
vuppalasampath
Guest







rtc 12c887 c code for interfacing with pic16f877a
PostPosted: Thu Aug 10, 2006 10:52 pm     Reply with quote

Ttelmah wrote:
The accuracy of the DS1302, is completely down to how good your crystal is (and how accurately it is trimmed). Yes, you can drive the DS12C887, but you will need a lot of pins, and these are not that much more accurate than you are already achieving (the basic 'accuracy', is only about 1minute/month). Choose a crystal which is warranted to a higher accuracy, look carefully at the capacitance round this part of the circuit, and/or trim the oscillator, and the 1302, will beat the 12C887 'hands down'. I have some systems using a crystal oven, with a 1302, and some have drifted less than 1 second, in over a year...
Even without the cost of a crystal oven, with a good crystal, and some care in the layout, 30 seconds/year, is fairly typical for the 1302. You are trying to use a 'sledgehammer to crack a nut', and won't get much better results than you are already achieving...

Best Wishes
Guest








Re: How to use DS12C887
PostPosted: Thu Aug 10, 2006 10:58 pm     Reply with quote

NewSpace wrote:
Dear Master~!

Hi there?

I used DS1302... But It's have a offset about 1minute / 1 week
If 1 month different about 4minute...
So I wanna DS12C887...
But I don't how to connect wire and Program...
I wanna help App. code...
Thank you~!
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