DS3231 questions and time accuracy

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  • I have the Pico, and setup an Adafruit DS3231 board with it. I used the info on this page. I am confused about the point:

    To set the day. The day is required so that the clocks move forwards
    and backwards for daylight saving in the UK. Please note that you need
    to call the readDateTime function at least every second for this to

    rtc.setDow("day of the week")

    At initial setup, I set the Dow to be the day e.g. ("Friday") and set the date and time per that page.

    Is setting Dow a requirement? I'm in Australia in a non-daylight saving location. I wonder if setting this is causing an issue I've noticed recently with the time, i.e. when I check the time after running the device & battery-backed RTC over a long period (e.g. 3 days continuously) I found the time is one hour out (shows one hour earlier than the true time). Has anyone else seen this issue?



  • Yes, that all looks a bit confusing. It seems that daylight saving couldn't be turned off with that JS module.

    I've just made some changes to the module for you - but I don't have anything here to test with.

    Please can you try:

    var rtc = require("DS3231").connect(I2C1, {
      DST : false  // don't make UK daylight saving changes automatically

    And hopefully that'll solve the problems for you

  • Thanks @Gordon for that - sorry for the delay - I needed to test this over a couple of days to make sure this worked, and it does. A small suggestion on your DS3231 page - you mention "optional option (DST) object" but it's not clear whether the default (if option is not set) goes to DST enabled or not. Is the default now DST = false if the optional value is not passed in at initialisation time? Perhaps it's worthwhile to update that page to make that clear. Anyway, thanks again for the update.

  • Thanks! I'll update the docs.

    The default is actually true - it's unfortunate, but I try to make sure that when stuff like this changes, code that was written before will still work on the same way.

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DS3231 questions and time accuracy

Posted by Avatar for Michael @Michael