I recently devised a quick project to interface an Attiny2313 with a DS1337 real-time clock from Maxim.
So far, I'm using the Tiny to handle both the time-checking via i2c (using the USI hardware) and the time-displaying via a 4-digit seven segment display.
So far everything is working except for the time-keeping on the DS1337 RTC, which I hoped would be something that would be handled entirely by the chip. Right now, the time is running much faster than normal. 60 seconds of our time is more like 70 seconds on the RTC.
I dug into why the clock might run fast, and I started by replacing the crystal with the correct 6 [pF] 32.768 [kHz] crystal. Still runs fast.
My only other guess at this point is that it has to do with the way my etched PCB is organized.
Has anyone else ever had their real-time clock chips from Maxim run fast?
Thanks in advance for reading!