Zephyr applications use the nrf51_pca10028 board configuration to run on the nRF51 Development Kit (PCA10028) hardware. It provides support for the Nordic Semiconductor nRF51822 ARM Cortex-M0 CPU and the following devices:

  • ADC
  • GPIO
  • I2C
  • NVIC
  • PWM
  • RADIO (Bluetooth Low Energy)
  • RTC
  • Segger RTT (RTT Console)
  • SPI
  • UART
  • WDT
nRF51 PCA10028 DK

nRF51 PCA10028 DK (Credit: Nordic Semi)

More information about the board can be found at the nRF51 DK website [1]. The Nordic Semiconductor Infocenter [2] contains the processor’s information and the datasheet.


nRF51 DK has two external oscillators. The frequency of the slow clock is 32.768 kHz. The frequency of the main clock is 16 MHz.

Supported Features

The nrf51_pca10028 board configuration supports the following nRF51 hardware features:

Interface Controller Driver/Component
ADC on-chip adc
CLOCK on-chip clock_control
FLASH on-chip flash
GPIO on-chip gpio
I2C(M) on-chip i2c
NVIC on-chip arch/arm
PWM on-chip pwm
RADIO on-chip Bluetooth
RTC on-chip system clock
RTT Segger console
SPI(M/S) on-chip spi
UART on-chip serial
WDT on-chip watchdog

Other hardware features are not supported by the Zephyr kernel. See nRF51 DK website [1] and Nordic Semiconductor Infocenter [2] for a complete list of nRF51 Development Kit board hardware features.

Connections and IOs


  • LED1 (green) = P0.21
  • LED2 (green) = P0.22
  • LED3 (green) = P0.23
  • LED4 (green) = P0.24

Push buttons

  • BUTTON1 = SW1 = P0.17
  • BUTTON2 = SW2 = P0.18
  • BUTTON3 = SW3 = P0.19
  • BUTTON4 = SW4 = P0.20
  • BOOT = SW5 = boot/reset

Programming and Debugging


Follow the instructions in the Nordic nRF5x Segger J-Link page to install and configure all the necessary software. Further information can be found in Flashing. Then build and flash applications as usual (see Build an Application and Run an Application for more details).

Here is an example for the Hello World application.

First, run your favorite terminal program to listen for output.

$ minicom -D <tty_device> -b 115200

Replace <tty_device> with the port where the board nRF51 DK can be found. For example, under Linux, /dev/ttyACM0.

Then build and flash the application in the usual way.

# On Linux/macOS
cd $ZEPHYR_BASE/samples/hello_world
mkdir build && cd build

# On Windows
cd %ZEPHYR_BASE%\samples\hello_world
mkdir build & cd build

# Use cmake to configure a Ninja-based build system:
cmake -GNinja -DBOARD=nrf51_pca10028 ..

# Now run ninja on the generated build system:
ninja flash


Refer to the Nordic nRF5x Segger J-Link page to learn about debugging Nordic boards with a Segger IC.

Testing the LEDs and buttons in the nRF51 DK

There are 2 samples that allow you to test that the buttons (switches) and LEDs on the board are working properly with Zephyr:


You can build and flash the examples to make sure Zephyr is running correctly on your board. The button and LED definitions can be found in boards/arm/nrf51_pca10028/board.h.