nrf_delay_ms() vs app_timer

[Bragma]

Hi,

I have the need to wait a few ms, from 1 to 20, in several parts of my code and I was wondering what's the most energy efficient way of doing it. Notice I don't need precise timing, I am using SoftDevice and app scheduler. After starting, app_timer seems a winner but I was wondering if the start code may may overweight the advantages, in particular with small ms values. Has anyone any considerations on this?

Thanks!

[Bojan Potocnik]

app_timer uses hardware RTC timer (running on LF clock) while the nrf_delay_ms() is a blocking function using loops for the delay - therefore using nrf_delay_ms() causes the CPU to be running at full speed, consuming more energy than sleeping while waiting for next RTC interrupt (for app_timer handling).

[Bragma]

Hi, thanks for answering. Yes that was part of my consideration. I was wondering if for small ms values (ex: 1,2) the code executed to setup and start the timer + interrupt handling code may not be worth the busy waiting code in nrf_delay_ms.

I really don't have idea of how much time is spent for the timer setup and irq handling overhead.