accuracy of application timer with schedular on nRF52

RE: accuracy of application timer with schedular on nRF52

Susheel Nuguru — Fri, 04 Mar 2016 10:31:19 GMT

There are two ways which will have better performance than normal but softdevice scheduling will still have the preference:

using the app_timer with higher priority. You need to change this define in app_timer.c
#define RTC1_IRQ_PRI APP_IRQ_PRIORITY_LOW

The side-effect of this is that you cannot make SVC calls (calls to sd_xxx) from this high priority context.

2 . Using timeslots and implement your own app_timer. Then your app timer will become part of softdevice activity.

RE: accuracy of application timer with schedular on nRF52

schoensn — Fri, 04 Mar 2016 09:40:36 GMT

I have implemented the app_timer in the datathroughput test demo, that application sends 20 byte notifications as fast as possible.

is there a possiblity to implement a timer which is not delayed, although there is high activity going on in the softdevice?

RE: accuracy of application timer with schedular on nRF52

Susheel Nuguru — Wed, 02 Mar 2016 14:59:41 GMT

I am not sure of the exact accuracy of the app_timer library but I can for sure say that it does not add delay of 5ms. The interrupt handler for the app_timer is called from lower priority than the softdevice activity, so if there is some high priority activity going on in the softdevice, then your RTC handler will be delayed until that is finished.

If you want to quickly verify this, then run your app_timer code with softdevice disabled and you will see that the accuracy is acceptable.