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Eugeneo
Joined: 30 Aug 2005
Posts: 155
Location: Calgary, AB
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| osccal for the 675 |
 Posted: Mon Jan 23, 2006 8:54 pm |
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The Machx OSCCAL value is sometimes has a slightly different value than the factory value. I'm thinking my room temperature is about room temp and the Machx has a voltage regulator on it. My scope is not accurate enough to tell me which is right...
I know it's trivial. But which would you guys trust? |
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cmdrdan
Joined: 08 Apr 2005
Posts: 25
Location: Washington
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| Posted: Mon Jan 23, 2006 9:14 pm |
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Your home setup versus millions of dollars of production test equipment? Maybe it is my test engineer's bias, but I'd go for the factory numbers 
Dan |
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Ttelmah
Guest
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| Posted: Tue Jan 24, 2006 5:24 am |
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Personally, why not test the results?.
The OSCCAL values from the factory, are sometimes not that accurate. They are generated in a similar way to that used by Mach-X, but using a computerised DFM, rather than just counting pulses in a time period. I'd doubt if the Mach-X values would differ by much (typically just a couple of counts in the last significant bits). However it is relatively simple to write a program, that operates an output pin, counts for a long time (perhaps 100seconds), and then changes the pin again. Done right, the time can be tested with a stopwatch, and would give a 'check' quite easily, to well better than one part in one thousand. You would then 'know' which was the better result.
Best Wishes |
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