Using GPIO in LOW POWER MODE consuming less than 30uA.

[Harsha]

Hi, I am using nRF51422 with S130. I want my application to blink a LED every one second. For now I am using App Timer which solves the purpose but the current consumption is too high 1.2mA. Is there any way I could do this blinking with less consumption? say below 20uA?.

[keith v]

do you have serial enabled? are you still attached to the debugger i.e. a segger j-link? Both of those cause high currents. You have to disconnect the debugger and then reset the device to get low power.

But LESS than 30Ua? thats pushing it!

[Harsha]

Hi Keith, Thanks for your answer. I am using a custom board. If I blink the LED using RTC then the consumption is 17uA. When I use app TImer then the consumption is 1.2mA. Unfortunately there are only two RTCs available in NRF51 series. RTC0 is used by Softdevice and RTC1 is used by app timers to do the BLE operations. Suggest me some way to do this blinking.

[Susheel Nuguru]

app_timer is RTC1 so it should not use that much current. Are you sure that there is no other difference in your code? can you put snippets of your code here?

[Harsha]

Timer Create.PNG Timer Start.PNG

Aryan. Find the attached code. This is actually using App timer with S130 enabled. Consumption is 1.2mA. In the timer_a_handler i am blinking a LED.

Whereas Here RTCInit.PNG

I blink the LED using RTC interrupt without softdevice the consumption is 60uA during blink and 16uA during idle time.

Let me know what you feel.

[Susheel Nuguru]

Can you check if using app_timer without softdevice consumes less power? we can exclude softdevice if app_timer and your RTC code behaves same in terms of current consumption. If current consumption is still high after disabling softdevice and using app_timer, then you have something else in the code (probably enabling some hardware maybe GPIOTE?)