https://devzone.nordicsemi.com/f/nordic-q-a/22799/make-and-call-a-c-functionUsing Keil MDK Lite v 5.22, writing code in C for nRF52, with SDK 12. Example code works. How does one declare a function, define it, and call it? I&#39;ve created a new module: myFunction.c and a header file: myFunction.h. I added a folder underen-USTelligent Community 13Thu, 15 Jun 2017 01:24:05 GMThttps://devzone.nordicsemi.com/thread/89631?ContentTypeID=1Thu, 15 Jun 2017 01:24:05 GMT137ad170-7792-4731-bb38-c0d22fbe4515:c7c7018e-c451-45b2-a2be-3b734b27362crobinvice<p>OK, I found the problem. I was expecting there to be some non-ANSI C setting up of function declarations/definitions, but it turned out to be a path problem.</p> <p>While looking for a solution, I saw many references to path problems, but at first glance I didn&#39;t think it was the issue here. Since my header file was located in the same directory as the rest of my project, and the other project files were found, I didn&#39;t think there was a path issue.</p> <p>I tested it by placing my header file (myFunction.h) in the same path as stdio.h. Then my header file worked.</p> <p>So, the solution was to open the Windows File Explorer window to the folder where my header file was located and copy the path. Then I pasted it in the C/C++ Include Paths text box in the Options for Target dialog window at the end of all the other paths.</p> <p>I still don&#39;t know why it couldn&#39;t find the header file in the working directory without adding the path.</p> <p>Hopefully this will help someone else with similar problems.</p> <p>robin</p><div style="clear:both;"></div>