https://devzone.nordicsemi.com/f/nordic-q-a/70051/cmsis-rtos-error-isr-queue-overflow-on-rtc2Hello, we want to use RTC2 (RTC0 is used by SoftDevice, RTC1 by FreeRTOS) to keep track of time. I set NRFX_RTC2_ENABLED and NRFX_RTC_ENABLED in app_config.h. Code used for initialising RTC: cal_begin() is then called after nrf_sdh_enable_requesten-USTelligent Community 13Tue, 05 Jan 2021 18:42:42 GMThttps://devzone.nordicsemi.com/thread/287571?ContentTypeID=1Tue, 05 Jan 2021 18:42:42 GMT137ad170-7792-4731-bb38-c0d22fbe4515:e7f9b881-6731-4d8e-98be-7604e479f4d3rdvojmoc<p>Sorry, RTC0 is taken by SoftDevice, RTC1 by app_timer. mbedOS is RTOS used in application.&nbsp; IDE is Mbed Studio.</p><div style="clear:both;"></div>https://devzone.nordicsemi.com/thread/287433?ContentTypeID=1Tue, 05 Jan 2021 09:21:20 GMT137ad170-7792-4731-bb38-c0d22fbe4515:a6132e65-2028-46fc-97f6-baf2dd57291cSusheel Nuguru[quote user=""]we want to use RTC2 (RTC0 is used by SoftDevice, RTC1 by FreeRTOS) to keep track of time. I set&nbsp;<span>NRFX_RTC2_ENABLED</span><span>&nbsp;and&nbsp;</span>NRFX_RTC_ENABLED in app_config.h. Code used for initialising RTC:[/quote] <p>&nbsp;I am guessing that you wont be using RTX and FreeRTOS both in your application!!?? If you are only using one RTOS you can use RTC1.</p> <p>Where did you get this RTOS port for nRF52840? is this MBed related stuff, if so, you need ask this question in the MBed forums as we know very little about the development of their SDKs</p><div style="clear:both;"></div>