Hi Vasile, > I can only guess 1ppb OCXO will cost you more than your board+your > programming time+many other toys. You can't test that with a 2ppm > oscillator, is useless. And you will not able to test for 1S output in a > short time because you need a periodmeter with 11digits and it's resolution > equal with the last digit accuracy. This kind of tool AFIK is very hard to > find (if exist). Maybe at NASA? > So what left is a weekly or monthly time accuracy check... > Some philosophers said that time does not exist. Others say time is relative and that is (however not in the sense intended) is useful in this case. From my first posting:
> You could test this with an additional counter in the 38.14 ms isr, > that is just incremented and printed as a reference each second, > together with remainder_count, count1 and second_count. Let it > run for a minute, print the outcome on a sheet of paper (or put in > in excel) and check if it is exactly what you think it is. (my guess > now is your clock is about .4% off). You don't want to test if you oscilator is at the right speed, you want to know if you processing is correct, relative to the cpu clock. > The length of the interrupt routine may affect the time, if an interrupt > event is lost (you don't have only that code in your ISR). If the length of the isr is relevant depends on the way the timer is used. Verify the code and datasheet (this is correct as far as I can see). In addition to this, check the isr lenght (toggle io pin, measure with scope or logic analyser). More general (i guess a tip on software engineering ;) test components and verify if they are working - this is much more effective than testing a complex system as a whole. Joep -- You received this message because you are subscribed to the Google Groups "jallib" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/jallib?hl=en.
