Testing and optimization

For simplicity, this guide will refer to both samples and applications as “applications”.

Each application in the nRF Connect SDK comes with its own testing instructions. Follow these instructions to make sure that the application runs as expected.

Information about the current state of the application is usually provided through LEDs, Universal Asynchronous Receiver/Transmitter (UART), or both. See the user interface section of the application’s documentation for the LED states or available UART commands.

To see the UART output, connect to the development kit (DK) with a terminal emulator. The default serial port settings are the following:

Default serial port connection settings for Nordic Semiconductor devices

Baud rate

Data bits

Stop bits


UART Hardware Flow Control (UART HWFC)




No parity


Use one of the following methods:

You can use the nRF Connect Serial Terminal app, which you can install from nRF Connect for Desktop. It establishes serial communication with the device, sends commands through UART, and also displays the UART output.

The app is available for Windows, Linux, and macOS.

To connect to the DK with Serial Terminal, complete the following steps:

  1. Open the Serial Terminal app.

  2. Connect the DK to the PC with a USB cable.

  3. Power on the DK.

  4. Click Select Device and select the particular kit entry from the drop-down list in the Serial Terminal.

  5. Select the serial port you want to connect to from the drop-down list.

  6. Configure the serial port connection parameters using the default serial port connection settings listed at the top of this page.

  7. Click Connect to port.

nRF Connect Serial Terminal starts the serial communication with the kit.

For more information about how to connect using the app, see the steps in the Serial Terminal documentation.

The nRF Connect SDK provides a common set of features and options for debugging and optimizing the application performance. This includes a multilevel logging system that can be enabled and configured independently for different modules and logging backends (such as UART, J-Link RTT or Spinel), and support for writing unit tests using Unity and CMock.


If you want to go through dedicated training related to some of the topics covered here, enroll in the nRF Connect SDK Intermediate course in the Nordic Developer Academy.