I'm not an expert, but I saw in datasheet that DS3231 works on 2ppm, so the accuracy should be about 5s per month.Please correct me if I'm wrong.
i bought modules on ebay. One is ZS-042 and on second is only "LC" sign.Thats they look:http://i.ebayimg.com/00/s/NzAwWDcwMA==/z/UzoAAOxyFd1SKA37/$(KGrHqJ,!o4FI(f)kVNRBSK!37gVsQ~~60_35.JPGThe second (litle) i set up about 6month ago and right now it has about 16 min delayI thought that delay will be couple of seconds per year.
Could you tell me how did you connect your RTC? I use only SCL and SDA. How about SQW and 32K?
How do you think. Is it problem with module or code?Could you tell me where did you buy your RTC, or recomend me some more accurate RTC?
were you able to test your DS3231?They only just arrived and I set them both up Saturday morning so not enough time has passed yet.I set up 5 ZS-042 and leave for 4 days only with coin battery. After that time i check te time and every RTC gave me different resault. It was about 10 seconds lag.One of them has 2min delay. Could you tell me which libs do you use?
I just bought some DS3231 chips (the 8 pin version) and just add the battery, decoupling and pullup resistors myself.