Current comsumption during button pressed and don't let go

Question

Hi all! 
 I got a little problem with my ble device.
That is: my device takes system_off mode as initial mode, when being pressed the button, it will wake up and start advertising (just the same as the ble_app_hrs example). 
 And the problem is: I added this code to my button:
while(nrf_gpio_pin_read(EVAL_BOARD_BUTTON_0) == 0) ; 
in order to keep the program runing forever here if I press the button and don't let go. Then i measured the current: about 4 mA,and I can not accept this current comsumption.
Can you tell me a method to decrease the current comsumption?(had better decrease to uA level) 
 By the way, I have try:
while(nrf_gpio_pin_read(EVAL_BOARD_BUTTON_0) == 0) sd_app_event_wait();
and there seems to be no help. 
 Looking forward to your reply, thank you very much!

Hung Bui · Accepted Answer

Hi kk, 
 The 4mA means the CPU haven't entered sleep mode yet. 
 Have you cleared the event register before you enter the loop ?
Also it's not a good idea to have a loop for sleep inside the interrupt handler, you would need a higher priority to wake the chip up. 
 I would suggest you to catch the pulse when you release the button instead of when you pressing it (for example instead of GPIO_PIN_CNF_SENSE_High you use GPIO_PIN_CNF_SENSE_Low )
So that the chip only wake up when you release the button.