I'm prototyping a few bits for a bigger project I'm working on, and part of it requires a pretty accurate RTC.
I bought this DS1307 IC: http://cpc.farnell.com/jsp/search/productdetail.jsp?SKU=SC08159
and paired it up with this crystal http://cpc.farnell.com/jsp/search/productdetail.jsp?SKU=SC08198
It's wired up according to the standard DS1307 datasheet schematics, including the use of a pair of 4K7ohm pull up resistors on the SCL and SDA lines (which a lot of people seem to miss out), and a 3v coin cell battery.
In addition, I am using a standard 16x2 line LCD to output the time and date that is read from the DS1307.
Everything is running fine - almost. I was able to set an initial time with no problem, and that is remembered correctly through power off. The problem is that the clock is running fast. I left it running (fully powered) overnight, and it gained approximately 30 seconds in 10 hours. For the project I'm working on that's useless, I really want better than a few seconds a week if possible.
Is there any obvious trouble shooting steps I can take?
I'll post a pic of the breadboard and the sketch (although that is incredibly simple) when I get home this evening if it'll help.