Keep the DS3231; it's very accurate. One of my clocks uses it, and it has drifted about 10 seconds since daylight savings started more than 6 months ago. My wristwatch demo board has been running 1.5 years and it's also within a few seconds. If you want anything better, you'll probably need GPS or a rubiduim time standard.
I got a few laughs from a $1 Chinese RTC board; wickedly inaccurate. I just swapped the DS3231 with a genuine Maxim device and use that in my clock. I recall most crystals are accurate to around 10ppm, which is about 1 second per day. My interpretation of that is the manufacturing tolerances result in multiple batches of crystals that will fall within 10ppm of their rated frequency; I suppose you can pay more for cherry-picked units that are more accurate. I doubt individual crystals drift back-n-forth, so you could add some offset to your software and fine-tune it to each crystal if you dont want to use RTC/GPS/Internet time. -- You received this message because you are subscribed to the Google Groups "neonixie-l" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send an email to [email protected]. To view this discussion on the web, visit https://groups.google.com/d/msgid/neonixie-l/504011be-4e4b-47d5-92e6-df6fa090ab5e%40googlegroups.com. For more options, visit https://groups.google.com/d/optout.
