Getting started with the Nordic nRF52840-DK - FreeRTOS

Getting started with the Nordic nRF52840-DK


This reference integration is hosted on the Amazon-FreeRTOS repository which is deprecated. We recommend that you start here when you create a new project. If you already have an existing FreeRTOS project based on the now deprecated Amazon-FreeRTOS repository, see the Amazon-FreeRTOS Github Repository Migration Guide.

This tutorial provides instructions for getting started with the Nordic nRF52840-DK. If you do not have the Nordic nRF52840-DK, visit the AWS Partner Device Catalog to purchase one from our partner.

Before you begin, you need to Set up AWS IoT and Amazon Cognito for FreeRTOS Bluetooth Low Energy.

To run the FreeRTOS Bluetooth Low Energy demo, you also need an iOS or Android mobile device with Bluetooth and Wi-Fi capabilities.


If you are using an iOS device, you need Xcode to build the demo mobile application. If you are using an Android device, you can use Android Studio to build the demo mobile application.


This tutorial contains instructions for the following getting started steps:

  1. Connecting your board to a host machine.

  2. Installing software on the host machine for developing and debugging embedded applications for your microcontroller board.

  3. Cross compiling a FreeRTOS demo application to a binary image.

  4. Loading the application binary image to your board, and then running the application.

  5. Interacting with the application running on your board across a serial connection, for monitoring and debugging purposes.

Set up the Nordic hardware

Connect your host computer to the USB port labeled J2, located directly above the coin cell battery holder on your Nordic nRF52840 board.

For more information about setting up the Nordic nRF52840-DK, see the nRF52840 Development Kit User Guide.

Set up your development environment

Download and install Segger Embedded Studio

FreeRTOS supports Segger Embedded Studio as a development environment for the Nordic nRF52840-DK.

To set up your environment, you need to download and install Segger Embedded Studio on your host computer.

To download and install Segger Embedded Studio
  1. Go to the Segger Embedded Studio Downloads page, and choose the Embedded Studio for ARM option for your operating system.

  2. Run the installer and follow the prompts to completion.

Set up the FreeRTOS Bluetooth Low Energy Mobile SDK demo application

To run the FreeRTOS demo project across Bluetooth Low Energy, you need to run the FreeRTOS Bluetooth Low Energy Mobile SDK demo application on your mobile device.

To set up the FreeRTOS Bluetooth Low Energy Mobile SDK Demo application
  1. Follow the instructions in Mobile SDKs for FreeRTOS Bluetooth devices to download and install the SDK for your mobile platform on your host computer.

  2. Follow the instructions in FreeRTOS Bluetooth Low Energy Mobile SDK demo application to set up the demo mobile application on your mobile device.

Establish a serial connection

Segger Embedded Studio includes a terminal emulator that you can use to receive log messages across a serial connection to your board.

To establish a serial connection with Segger Embedded Studio
  1. Open Segger Embedded Studio.

  2. From the top menu, choose Target, Connect J-Link.

  3. From the top menu, choose Tools, Terminal Emulator, Properties, and set the properties as instructed in Installing a terminal emulator.

  4. From the top menu, choose Tools, Terminal Emulator, Connect port (115200,N,8,1).


The Segger embedded studio terminal emulator does not support an input capability. For this, use a terminal emulator like PuTTy, Tera Term, or GNU Screen. Configure the terminal to connect to your board by a serial connection as instructed in Installing a terminal emulator.

Download and configure FreeRTOS

After you set up your hardware and environment, you can download FreeRTOS.

Download FreeRTOS

To download FreeRTOS for the Nordic nRF52840-DK, go to the FreeRTOS GitHub page and clone the repository. See the file for instructions.

  • In this topic, the path to the FreeRTOS download directory is referred to as freertos.

  • Space characters in the freertos path can cause build failures. When cloning or copying the repository, make sure the path you create does not contain space characters.

  • The maximum length of a file path on Microsoft Windows is 260 characters. Long FreeRTOS download directory paths can cause build failures.

  • Because the source code may contain symbolic links, if you're using Windows to extract the archive, you may have to:

    • Enable Developer Mode or,

    • Use a console that is elevated as administrator.

    In this way, Windows can properly create symbolic links when it extracts the archive. Otherwise, symbolic links will be written as normal files that contain the paths of the symbolic links as text or are empty. For more information, see the blog entry Symlinks in Windows 10!.

    If you use Git under Windows, you must enable Developer Mode or you must:

    • Set core.symlinks to true with the following command:

      git config --global core.symlinks true
    • Use a console that is elevated as administrator whenever you use a git command that writes to the system (for example, git pull, git clone, and git submodule update --init --recursive).

Configure your project

To enable the demo, you need to configure your project to work with AWS IoT. To configure your project to work with AWS IoT, your device must be registered as an AWS IoT thing. You should have registered your device when you Set up AWS IoT and Amazon Cognito for FreeRTOS Bluetooth Low Energy.

To configure your AWS IoT endpoint
  1. Sign in to the AWS IoT console.

  2. In the navigation pane, choose Settings.

    Your AWS IoT endpoint appears in the Device data endpoint text box. It should look like Make a note of this endpoint.

  3. In the navigation pane, choose Manage, and then choose Things. Make a note of the AWS IoT thing name for your device.

  4. With your AWS IoT endpoint and your AWS IoT thing name on hand, open freertos/demos/include/aws_clientcredential.h in your IDE, and specify values for the following #define constants:

    • clientcredentialMQTT_BROKER_ENDPOINT Your AWS IoT endpoint

    • clientcredentialIOT_THING_NAME Your board's AWS IoT thing name

To enable the demo
  1. Check that the Bluetooth Low Energy GATT Demo is enabled. Go to vendors/nordic/boards/nrf52840-dk/aws_demos/config_files/iot_ble_config.h, and add #define IOT_BLE_ADD_CUSTOM_SERVICES ( 1 ) to the list of define statements.

  2. Open vendors/nordic/boards/nrf52840-dk/aws_demos/config_files/aws_demo_config.h, and define either CONFIG_OTA_MQTT_BLE_TRANSPORT_DEMO_ENABLED or CONFIG_OTA_HTTP_BLE_TRANSPORT_DEMO_ENABLED as in this example.

    /* To run a particular demo you need to define one of these. * Only one demo can be configured at a time * * CONFIG_BLE_GATT_SERVER_DEMO_ENABLED * CONFIG_MQTT_BLE_TRANSPORT_DEMO_ENABLED * CONFIG_SHADOW_BLE_TRANSPORT_DEMO_ENABLED * CONFIG_OTA_MQTT_BLE_TRANSPORT_DEMO_ENABLED * CONFIG_OTA_HTTP_BLE_TRANSPORT_DEMO_ENABLED * CONFIG_POSIX_DEMO_ENABLED * * These defines are used in iot_demo_runner.h for demo selection */ #define CONFIG_OTA_MQTT_BLE_TRANSPORT_DEMO_ENABLED
  3. Since the Nordic chip comes with very little RAM (250KB), the BLE configuration might need to be changed to allow for larger GATT table entries compared to the size of each attribute. In this way you can adjust the amount of memory the application gets. To do this, override the definitions of the following attributes in the file freertos/vendors/nordic/boards/nrf52840-dk/aws_demos/config_files/sdk_config.h:


      The number of vendor-specific UUIDs. Increase this count by 1 when you add a new vendor-specific UUID.


      Attribute Table size in bytes. The size must be a multiple of 4. This value indicates the set amount of memory dedicated for the attribute table (including the characteristic size), so this will vary from project to project. If you exceed the size of the attribute table you will get a NRF_ERROR_NO_MEM error. If you modify the NRF_SDH_BLE_GATTS_ATTR_TAB_SIZE usually you must also reconfigure the RAM settings.

    (For tests, the location of the file is freertos/vendors/nordic/boards/nrf52840-dk/aws_tests/config_files/sdk_config.h.)

Build and run the FreeRTOS demo project

After you download FreeRTOS and configure your demo project, you are ready to build and run the demo project on your board.


If this is the first time that you are running the demo on this board, you need to flash a bootloader to the board before the demo can run.

To build and flash the bootloader, follow the steps below, but instead of using the projects/nordic/nrf52840-dk/ses/aws_demos/aws_demos.emProject project file, use projects/nordic/nrf52840-dk/ses/aws_demos/bootloader/bootloader.emProject.

To build and run the FreeRTOS Bluetooth Low Energy demo from Segger Embedded Studio
  1. Open Segger Embedded Studio. From the top menu, choose File, choose Open Solution, and then navigate to the project file projects/nordic/nrf52840-dk/ses/aws_demos/aws_demos.emProject

  2. If you are using the Segger Embedded Studio terminal emulator, choose Tools from the top menu, and then choose Terminal Emulator, Terminal Emulator to display information from your serial connection.

    If you are using another terminal tool, you can monitor that tool for output from your serial connection.

  3. Right-click the aws_demos demo project in the Project Explorer, and choose Build.


    If this is your first time using Segger Embedded Studio, you might see you a warning "No license for commercial use". Segger Embedded Studio can be used free of charge for Nordic Semiconductor devices. Request a free license then, during setup choose Activate Your Free License, and follow the instructions.

  4. Choose Debug, and then choose Go.

    After the demo starts, it waits to pair with a mobile device across Bluetooth Low Energy.

  5. Follow the instructions for the MQTT over Bluetooth Low Energy Demo Application to complete the demo with the FreeRTOS Bluetooth Low Energy Mobile SDK demo application as the mobile MQTT proxy.


For general troubleshooting information about Getting Started with FreeRTOS, see Troubleshooting getting started.