John Boxall over at Tronixstuff has posted a detailed tutorial on how to on how to use DS1307 and DS3231 real-time clock modules with Arduino:
There are two main differences between the ICs on the real-time clock modules, which is the accuracy of the time-keeping. The DS1307 used in the first module works very well, however the external temperature can affect the frequency of the oscillator circuit which drives the DS1307’s internal counter.
This may sound like a problem, however will usually result with the clock being off by around five or so minutes per month. The DS3231 is much more accurate, as it has an internal oscillator which isn’t affected by external factors – and thus is accurate down to a few minutes per year at the most. If you have a DS1307 module- don’t feel bad, it’s still a great value board and will serve you well.
Advice: if you are really cheap and want to buy local only for toying around get the DS1307.
All others: the price gap in Chinas Mom&Pop-ebay shops is…. oh, the DS3231 are actually cheaper.
Lots of DS1307 suffer from crystals abused during soldering, so they are far away from good. Chance is you get one that if five minutes off a day… waste of money.
In support of rumburacks comment:
http://edwardmallon.wordpress.com/2014/05/21/using-a-cheap-3-ds3231-rtc-at24c32-eeprom-from-ebay/
I’ve been putting the $1 DS3231 boards through their paces for quite a while now…and they have been performing well.
Very nice article, Edward. Lots of useful informations and stuff about avoidable errors.
Thank you!