Need a 30 second interrupt - using RTC ?

RE: Need a 30 second interrupt - using RTC ?

Fred — Wed, 10 Apr 2019 18:42:49 GMT

Under the hood, app_timer just uses RTC1, so you're still using RTC ;-)

(SoftDevice uses RTC0 by the way)

As for the power consumption; 5 uA seems just a little bit on the high side. Your application is definitly sleeping, so that's ok, but for only RTC running and system in low-power system_on, one would expect around 2 uA. But when you get in this range, there is a whole set of things that might be important of course, such as quiescent currents in the board, proper pin configuration (no floating pins!), measurement accuracy, etc. So, I guess it depends on how bad you want that extra 3 uA ;-)

RE: Need a 30 second interrupt - using RTC ?

kjhuebner — Wed, 10 Apr 2019 18:20:52 GMT

For app_timer, what are you measuring for power usage during the sleep time?

I decided to give up on RTC and go with the app_timer, similar to your code.

I am currently measuring 5uA @3V power usage during sleep when using app_timer. This is not bad, but I am interested if I can reduce power further.

Thanks, Ken

RE: Need a 30 second interrupt - using RTC ?

Fred — Wed, 10 Apr 2019 17:35:04 GMT

In my application I'm doing something similar using app_timer: sleeping and then waking up every minute to a send of advertising packets. During this time, the system is low-power, so no worries about waking up the CPU.