sdk 13 app_timer 24 hour long timer

[jale]

Hi,

there were some significant changes to app_timer in sdk13.

I cannot use now the PRESCALER e.g. to 255 in order to configure the clock in such way to be able to tirgger event every eg. 24 hours.

So how should I do this now?

Any idea? Much appreciate your help/

Best wishes, Jacek

[Joakim Jakobsen]

Hi Jacek!
Did you take a look at the app_timer library in SDK 13? Especially the migration note is worth taking a look at.
Best regards.

[jale]

Hi Joakim,

Yes I did. But in In sdk_config.h there is no PRESCALER = 256 in order to have 128 Hz freq. So I did declare an addition entry there like below.

#if APP_TIMER_ENABLED // APP_TIMER_CONFIG_RTC_FREQUENCY - Configure RTC prescaler.

// <0=> 32768 Hz // <1=> 16384 Hz // <3=> 8192 Hz // <7=> 4096 Hz // <15=> 2048 Hz // <31=> 1024 Hz // <255=> 128 Hz

It will give me:

fRTC [kHz] = 32.768/(255+1) = 128

and the timer will wrap around every (2^24) * 1/128 Hz = 131 072 s -> what gives me just over 36h of wrap around.

Is that the right apporach?

Best wishes, Jacek

[Joakim Jakobsen]

Hi again Jacek.
Yes, there shouldn't be any problem defining the prescaler like you do in the comment above.
That should provide you with a prescaler value of 255 and an overflow of 36,4 hours.
Best regards.