[time-nuts] DS3231m 1HZ output stability

[Hal Murray]

> # Delta GPS: 3659, Delta RTC: 3660
> # Delta GPS: 3659, Delta RTC: 3659
> > # Delta GPS: 3658, Delta RTC: 1984
> > # Delta GPS: 3658, Delta RTC: 1984
> # Delta GPS: 3659, Delta RTC: 3659
> # Delta GPS: 3659, Delta RTC: 3660


> I would like to ask if somebody did measurement for that Dallas DS32XX
> series chips. Is that 1PPS (1HZ square wave) stable there or it has some
> issues ? I am thinking that "burp" in my tests could be because of my  poor
> code or may be because of DS32XX doing temperature conversion every  second,
> which cause an impact to the 1HZ output. I would be interested  to hear any
> information about. From the datasheet of DS3231m , that 1HZ  from DS32XX
> should be stable.

My guess would be a software bug, but I don't know anything about what you 
did there.

You might try swapping the two input wires.

Do you have a scope?  Any overshoot/bounce crap?  (Not likely with low power 
CMOS.)

Notice that the 2 strange lines came when the GPS had only 3658 ticks.  

I have data from one of the DS32xx chips, but I was looking at a 32KHz signal 
rather than the a 1 Hz.  I don't remember any quirks.


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