Blinky, your “Hello World!”, on a nRF52 Development Kit

This tutorial shows you how to create, build, and run the Blinky application on a nRF52 Development Kit.

Note that there are several versions of the nRF52 Development Kit in the market. The boards tested with this tutorial are listed under “Prerequisites”.


This tutorial uses the Nordic nRF52-DK board.

Create a Project

Create a new project if you do not have an existing one. You can skip this step and proceed to Create the Targets if you already have a project created.

Run the following commands to create a new project:

$ mkdir ~/dev
$ cd ~/dev
$ newt new myproj
Downloading project skeleton from apache/mynewt-blinky...
Installing skeleton in myproj...
Project myproj successfully created.
$ cd myproj
$ newt install

Create the Targets

Create two targets for the nRF52-DK board - one for the bootloader and one for the Blinky application.

Run the following newt target commands, from your project directory, to create a bootloader target. We name the target nrf52_boot:

Note: This tutorial uses the Nordic nRF52-DK board. You must specify the correct bsp for the board you are using.

  • For the Rigado Eval Kit choose @apache-mynewt-core/hw/bsp/bmd300eval instead (in the highlighted lines)
$ newt target create nrf52_boot
$ newt target set nrf52_boot app=@apache-mynewt-core/apps/boot
$ newt target set nrf52_boot bsp=@apache-mynewt-core/hw/bsp/nrf52dk
$ newt target set nrf52_boot build_profile=optimized

Run the following newt target commands to create a target for the Blinky application. We name the target nrf52_blinky.

$ newt target create nrf52_blinky
$ newt target set nrf52_blinky app=apps/blinky
$ newt target set nrf52_blinky bsp=@apache-mynewt-core/hw/bsp/nrf52dk
$ newt target set nrf52_blinky build_profile=debug

You can run the newt target show command to verify the target settings:

$ newt target show

Build the Target Executables

Run the newt build nrf52_boot command to build the bootloader:

$ newt build nrf52_boot
Building target targets/nrf52_boot
Compiling repos/apache-mynewt-core/boot/bootutil/src/image_ec256.c
Compiling repos/apache-mynewt-core/boot/bootutil/src/image_ec.c
Compiling repos/apache-mynewt-core/boot/bootutil/src/image_rsa.c
Compiling repos/apache-mynewt-core/crypto/mbedtls/src/aes.c
Compiling repos/apache-mynewt-core/boot/bootutil/src/loader.c
Compiling repos/apache-mynewt-core/boot/bootutil/src/image_validate.c
Compiling repos/apache-mynewt-core/boot/bootutil/src/bootutil_misc.c
Compiling repos/apache-mynewt-core/apps/boot/src/boot.c


Archiving sys_mfg.a
Archiving sys_sysinit.a
Archiving util_mem.a
Linking ~/dev/myproj/bin/targets/nrf52_boot/app/apps/boot/boot.elf
Target successfully built: targets/nrf52_boot

Run the newt build nrf52_blinky command to build the Blinky application:

$ newt build nrf52_blinky
Building target targets/nrf52_blinky
Assembling repos/apache-mynewt-core/hw/bsp/nrf52dk/src/arch/cortex_m4/gcc_startup_nrf52_split.s
Compiling repos/apache-mynewt-core/hw/bsp/nrf52dk/src/sbrk.c
Compiling repos/apache-mynewt-core/hw/cmsis-core/src/cmsis_nvic.c
Compiling repos/apache-mynewt-core/hw/drivers/uart/uart_hal/src/uart_hal.c
Assembling repos/apache-mynewt-core/hw/bsp/nrf52dk/src/arch/cortex_m4/gcc_startup_nrf52.s
Compiling apps/blinky/src/main.c


Archiving sys_mfg.a
Archiving sys_sysinit.a
Archiving util_mem.a
Linking ~/dev/myproj/bin/targets/nrf52_blinky/app/apps/blinky/blinky.elf
Target successfully built: targets/nrf52_blinky

Sign and Create the Blinky Application Image

Run the newt create-image nrf52_blinky 1.0.0 command to create and sign the application image. You may assign an arbitrary version (e.g. 1.0.0) to the image.

$ newt create-image nrf52_blinky 1.0.0
App image succesfully generated: ~/dev/myproj/bin/targets/nrf52_blinky/app/apps/blinky/blinky.img

Connect to the Board

  • Connect a micro-USB cable from your computer to the micro-USB port on the nRF52-DK board.
  • Turn the power on the board to ON. You should see the green LED light up on the board.

Load the Bootloader and the Blinky Application Image

Run the newt load nrf52_boot command to load the bootloader onto the board:

$ newt load nrf52_boot
Loading bootloader

Run the newt load nrf52_blinky command to load the Blinky application image onto the board.

$ newt load nrf52_blinky
Loading app image into slot 1

You should see the LED1 on the board blink!

Note: If the LED does not blink, try resetting your board.

If you want to erase the flash and load the image again, you can run JLinkExe to issue an erase command.

Note: On Windows: Run the jlink command with the same arguments from a Windows Command Prompt terminal.

$ JLinkExe -device nRF52 -speed 4000 -if SWD
SEGGER J-Link Commander V5.12c (Compiled Apr 21 2016 16:05:51)
DLL version V5.12c, compiled Apr 21 2016 16:05:45

Connecting to J-Link via USB...O.K.
Firmware: J-Link OB-SAM3U128-V2-NordicSemi compiled Mar 15 2016 18:03:17
Hardware version: V1.00
S/N: 682863966
VTref = 3.300V

Type "connect" to establish a target connection, '?' for help
Cortex-M4 identified.
Erasing device (0;?i?)...
Comparing flash   [100%] Done.
Erasing flash     [100%] Done.
Verifying flash   [100%] Done.
J-Link: Flash download: Total time needed: 0.363s (Prepare: 0.093s, Compare: 0.000s, Erase: 0.262s, Program: 0.000s, Verify: 0.000s, Restore: 0.008s)
Erasing done.