https://devzone.nordicsemi.com/f/nordic-q-a/75318/app-timer-startHi, at the description of the function : app_timer_start The parameter &quot;timeout_ticks&quot; has a minimum value, what about the maximum value? in other words can we use this app_timer_start function to start a timer for hours? Is the limit is justen-USTelligent Community 13Wed, 19 May 2021 11:53:46 GMThttps://devzone.nordicsemi.com/thread/310417?ContentTypeID=1Wed, 19 May 2021 11:53:46 GMT137ad170-7792-4731-bb38-c0d22fbe4515:0ffede10-bad0-4346-8b3b-7573cf502802Einar Thorsrud<p>Hi,</p> [quote user=""]The parameter &quot;timeout_ticks&quot; has a minimum value, what about the maximum value?[/quote] <p>The maximum value for the original app_timer implementation (app_timer.c) is MAX_RTC_COUNTER_VAL, which is (2^24)-1 =&nbsp;16777215. There was an issue in some SDK versions where half of this was the actual maximum due to a bug. And for app_timer2 if you are using that, the maximum value is 2^32-1 as the internal implementation has changed.</p> [quote user=""]Please let me know If my calculation is right\wrong.[/quote] <p>It depends. The&nbsp;original app_timer.c internally is 24 bit because of the RTC being 24 bit. So the correct would be&nbsp;((2^24) - 1)/32768 = 512 seconds. You can increase this by lowering the RTC frequency by using a prescaler though, which you do by modifying&nbsp;APP_TIMER_CONFIG_RTC_FREQUENCY in sdk_config.h.</p><div style="clear:both;"></div>