https://devzone.nordicsemi.com/f/nordic-q-a/378/nrf51822-dk-j-link-keil-step-f11-ok-step-over-f10-errif set breakpoint at DEF(), OK, ABC() can execute. if set breakpoint at ABC(), then Step(F11) in ABC() -- it&#39;s not function call, OK, if set breakpoint at ABC(), then StepOver(F10) ABC() -- Err!! **JLink Warning: T-bit of XPSR is 0 but should been-USTelligent Community 13Thu, 29 Aug 2013 06:53:53 GMThttps://devzone.nordicsemi.com/thread/1990?ContentTypeID=1Thu, 29 Aug 2013 06:53:53 GMT137ad170-7792-4731-bb38-c0d22fbe4515:a57e22e2-f873-4768-bbf3-1f9fccc57aedOle Morten<p>Which version of Keil&#39;s MDK are you using? I suspect this may be a known issue with versions &lt; 4.54, so I&#39;d recommend you to upgrade to a later one.</p> <p>It should also be possible to fix this by following the procedure stated <a href="http://www.segger.com/IDE_Integration_Keil.html#knownproblems">here</a> for your version of Keil.</p><div style="clear:both;"></div>https://devzone.nordicsemi.com/thread/1989?ContentTypeID=1Thu, 29 Aug 2013 01:34:05 GMT137ad170-7792-4731-bb38-c0d22fbe4515:c8de055f-5816-4035-8753-f996cdd5a28fbayi255<p>Use S110 v5.0</p><div style="clear:both;"></div>