I'm building a coin battery (CR2032) operated clock with a 12F629

The program uses TIMER1 interrupt configured to reload at 100hz and refresh variables each time.

On the main loop there is just a button push check loop to deliver time in case of pushing it.

For extending the battery life I tried to lower the cristal frequency (from 4M to 32K) but without luck in picbasic, I also disabled all hardware not in use (TMR0, WPU, VREF, COMP) and the pull-up on the button (GPIO3) is at 100K.

Right now the circuit is drawing 0,5mA and that is low but maybe i missing something else


My question is:
Did I miss something else to reduce power?

Also,
I was wondering if someone can point me up for some tips on how to proper design (software and hardware) for low power in timing aplications without using external RTCs
Because right now i'm guessing

Thanks