PCF8583 RTC alarm?

Hi,

I'm trying to implement the alarm function of a RTC PCF8583. I have no problem setting and reading time but I can't get my head around how to set up the alarm side!!

I want to do this so that I can set a future date/time and use the alarm output to wake my logger from sleep to start logging.

I've read its data sheet countless times and tried just about every combination but don't get anywhere. Can anyone offer a snippet of a working alarm setup to show me where I'm failing please?

Cheers,
Bill