Thanks for this Jack, that looks very useful! I've been doing a bit more research on this RTC stuff (I'm a bit of a noob)
and I've found a simular one called DS3234 which is SPI instead?? If someone could kindly enlighten me to what the difference is between I2C and SPI is that would be awesome. Also is this compatible with the attiny chips and the arduino platform.
..and then there's the DS3231m (http://www.maximintegrated.com/datasheet/index.mvp/id/6861
) which is the size I'm looking for as its smaller and has less pins but I can't find it anywhere.. this is getting confusing
any help would be much appreciated