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Building and running the first sample

This guide explains how to build and run the first sample (for example, Blinky).

Before you start building, remember to set up the environment first.

Build the Blinky sample

After completing the environment setup, use the following steps to build the Blinky sample on the command line.

  1. Open a terminal window.

  2. Go to my-workspace/ncs-playground directory created in the Setting up the environment section.

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    cd my-workspace/ncs-playground

  3. Build the sample using the west command, specifying the board (following the -b option) as dongle_nrf52840:

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    west build -p always -b dongle_nrf52840 samples/blinky

    Tip

    The -p always option forces a pristine build, and is recommended for new users. Users may also use the -p auto option, which will use heuristics to determine if a pristine build is required, such as when building another sample.

  4. After running the west build command, the build files can be found in build/zephyr.

Flash and run the sample

The sample is designed to work with the UF2 Bootloader, so that you can easily flash the sample using the UF2 Bootloader. The firmware can be found in build/zephyr with the name zephyr.uf2.

To flash the firmware, complete the following steps:

  1. Push and hold the button and plug your dongle into the USB port of your computer. Release the button after your dongle is connected. The RGB LED turns green.

  2. It will mount as a Mass Storage Device called UF2BOOT.

  3. Drag and drop zephyr.uf2 onto the UF2BOOT volume. The RGB LED blinks red fast during flashing.

  4. Re-plug the dongle and the Red LED will start to blink.

Next steps

Try more samples on nRF52840 MDK USB Dongle:

nRF Connect SDK and Zephyr also provide a variety of application samples and demos. Documentation for those is available in: