My second RTC module, another broken one [Solved]

If the battery is removed, the aging offset setting is lost.

THX. That’s unfortunate, but at least there is the mechanism.


I’ve always been curious why folks use an RTC module. You’ve got a crystal controlled Arduino Nano, UNO, whatever and a HARDWARE timer that spits out the values of the number of milliseconds since power ON. If you’re just interested in the time of day, why do you need an RTC? OK, there is a constant (if your microcontroller is in a relatively stable temperature area) drift in your 16mHz crystal but you can compensate for that. That’s what I do and it works great. I just measured that drift after a few days and I adjust the clock every midnight to catch up or slow down my clock. I was losing 89.65 seconds a day. I can show you my code if you really want but it’s really a simple concept (to me anyway).

  1. Battery backup for time keeping.

  2. Superior accuracy out of the box.

  3. The equivalent of many lines of code providing convenient year, month, date, day, hours, minutes and seconds values.

3.5 and don’t forget 31 days hath September &c.

  1. The equivalent of many lines of code implementing alarm clock functions

  2. Available 32Khz signal for accurate sequencing of a program. I use it to run my loop at 100 Hz, not 98-102 and then do some finicky fiddling.

But mostly 1. Battery backup for time keeping.

We all find the place to waste spend time on these things. So it really is a matter of what kind of fun you want to have.