https://devzone.nordicsemi.com/f/nordic-q-a/60733/program-is-frozen-after-starting-a-timer-with-softdeviceUsing: nRF52840-QIAA(build code: C0) 1024kB, GCC 8.2.1, Debug build (-O0), Softdevice S140 7.0.1, SDK v16.0.0 Source code: In UART console i see: &lt;info&gt; app_timer: RTC: initialized. &lt;info&gt; app: Before timer start So program freezed/crashed inen-USTelligent Community 13Tue, 28 Apr 2020 04:42:40 GMThttps://devzone.nordicsemi.com/thread/246956?ContentTypeID=1Tue, 28 Apr 2020 04:42:40 GMT137ad170-7792-4731-bb38-c0d22fbe4515:6fa370ad-869a-4899-92da-798d048d1575TereCratify<p>Yes, in map file function RTC1_IRQHandler comes from gcc_startup_nrf52840.S file.</p> <p></p> <p>It seems that i messed up order of source files in process of migration to CMake, and gcc_startup file was moved to the bottom in sources list. When i moved&nbsp;gcc_startup to the top timer started working, thanks for the help !</p><div style="clear:both;"></div>https://devzone.nordicsemi.com/thread/246802?ContentTypeID=1Mon, 27 Apr 2020 12:06:01 GMT137ad170-7792-4731-bb38-c0d22fbe4515:a798504d-cdff-4d70-883e-e5d794e780abVidar Berg<p>Hello,</p> <p>IRQ #17 is for RTC1, so it is a bit strange that the program appears to end up in the WDT handler (IRQn 16) instead.</p> <p>Could you check the *.map file to see if the RTC1_IRQHandler is being included in the drv_rtc.o object, and if it does, please check if this address + thumb bit matches the address at &lt;vector table start&gt; + 0x84.</p> <p></p> <p><img src="https://devzone.nordicsemi.com/resized-image/__size/320x240/__key/support-attachments/beef5d1b77644c448dabff31668f3a47-910f9504bb054bc5859e21ee4dcd2280/pastedimage1587989073286v1.png" alt=" " /></p><div style="clear:both;"></div>