Hi All,

I know how much we dread the DS1307 RTC discussions, but here goes.....


I recently added a DS1307 to my pic16f877 for a data logging project.
I read a serial string into the pic, and send out some serial data with an added time/date stamped onto it for loggin purposes......fairly simple stuff

I can write to the RTCC, and READ from the RTCC with good results...

However, for some reason it displays 90 (yes, NINETY!) seconds before it will increment the minutes.

Also, when the minutes reaches certain numbers, it will jump by 6 mins on the next increment.
For example 12:37:00 will change to 12:43:00 when the next 'minute increment' occurs.

I'm NOT using a 12pf 32,768khz Xtal at the moment, however i thought having the wrong Xtal would only make my clock run slow/fast.

I can't understand where i get 90secs from?

I am writing DECIMAL numbers into the RTCC, not hex etc, as i've seen people writing/reading in 2 different number formats which confused them.

Anyone seen this before?

Thanx,
Marty.