nrf52832: Modifying the prescaler value to save battery life

[Sami]

Hello,

I'm currently running our RTC using the default resolution of 32.768 kHz (30.517 micro-seconds), which means that we are not prescaling. If I desire to have a larger resolution (less overflow in the 24-bit counter) of say, 0.5ms (instead of 30.527us), how much battery life is saved? Has that been characterized? I would assume less register incrementing/overflowing would result in less battery consumption over the long-haul. Thank you.

[John]

I don't imagine that there is a lot of power savings to be gained by the prescaler unless it changes how often you come out of IDLE mode. Once the RTC peripheral is on I think it would burn about the same amount of power regardless of the prescaler. The data sheet indicates that it's typical power consumption is 0.1uA so there isn't a lot to gain there.

[Roger Clark]

The OP has not said what advertising interval or power level etc they are using.

Changing the advertising interval would most likely have a much bigger impact on total power consumption.

I've also heard of solutions that use an external device to do the lower power timing.

e.g put the MCU into its deepest sleep mode when its not being used and let the external (ultra low power) timer device, wake it via interrupt.

But the OP would need to model their individual set of circumstances to see what would give the minimal power usage.