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NewSpace
Joined: 23 Sep 2003 Posts: 12 Location: South KOREA
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How to use DS12C887 |
Posted: Thu Feb 03, 2005 2:30 am |
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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 |
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Ttelmah Guest
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Posted: Thu Feb 03, 2005 3:28 am |
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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 |
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Guest
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Try this |
Posted: Thu Feb 03, 2005 5:11 am |
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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. |
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vuppalasampath Guest
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rtc 12c887 c code for interfacing with pic16f877a |
Posted: Thu Aug 10, 2006 10:52 pm |
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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 |
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Guest
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Re: How to use DS12C887 |
Posted: Thu Aug 10, 2006 10:58 pm |
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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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