Hi everybody,
As a part of my long term project building wireless sensor nodes, I have been looking for a nice RTC chip. First I was drawn to the DS1307, but this part is 5V and only a clock without alarm functions. Googling to the internet I've found the PCF8563. This part is a "drop in" replacement for the DS1307, but offers a lower supply voltage (3.3V) and includes alarm functions. The chips can be sourced quite cheap from the internet and work like a charm with both 6pf and 12pf 32768kHz crystals.
A nice tutorial how to connect these things can be found using the following link: http://startingelectronics.com/beginners/start-electronics-now/tut16-arduino-clock/
It is written for the Arduino but can be adapted easily to the launchpad. Just change the LiquidCrystal pins to free pins on the Arduino and voila there you have a nice RTC that can be used for sprinkler projects or other projects. The alarm can be set on different days of the week (not a specific date), but with some program logic a calendared version should be possible.
I am thinking of writing a library out of the tutorial. Anyone interested?
Kind regards,
Eelco