To actually see what is happening on the development kit while the application is running, you must set up a J-Link debugging session. SEGGER Embedded Studio (SES) has an integrated debugger that you can use to step through your application.

Complete the following steps to start debugging:

  1. Configure your application to optimize the debugging experience. To do so, set CONFIG_DEBUG_OPTIMIZATIONS to y.
    See Configuring your application for instructions.
  2. Open your project in SES.
  3. Build and program your application to the kit as described in Building and programming a sample application.
  4. Select Debug > Go.
    Alternatively, press F5.
    The debugging interface looks like this:
    Debugging interface
    By default, the application will break in main. You can set additional break points, single-step through the application, read registers, and so on.

See the debugging section of the nRF Connect SDK tutorial on DevZone for more information about debugging in SES.