How to make Nrf51822 wake up by button, increment variable then sleep

Question

I've just started working with Nrf51822, I'm trying to make this scenario for weeks but i failed. 
 Plz help me! 
 How to make Nrf51822 wake up by a button click, increment a variable then go back to sleep?
i've tested __WFI() and __WFE() but it doesnt work.

Stefan Birnir Sverrisson · Accepted Answer

Hi 
 The system-on-wakeup-on-gpio is the most simple example for going to sleep, and wake up again on a button press. It is without using a softdevice. References to other useful examples can be fount in the current consumption guide , section "Measure current consumption"