.. zephyr:board:: nrf52840dk

Overview
********

The nRF52840 Development Kit (PCA10056) hardware provides support for the
Nordic Semiconductor nRF52840 ARM Cortex-M4F CPU and the following devices:

* :abbr:`ADC (Analog to Digital Converter)`
* CLOCK
* FLASH
* :abbr:`GPIO (General Purpose Input Output)`
* :abbr:`I2C (Inter-Integrated Circuit)`
* :abbr:`MPU (Memory Protection Unit)`
* :abbr:`NVIC (Nested Vectored Interrupt Controller)`
* :abbr:`PWM (Pulse Width Modulation)`
* RADIO (Bluetooth Low Energy and 802.15.4)
* :abbr:`RTC (nRF RTC System Clock)`
* Segger RTT (RTT Console)
* :abbr:`SPI (Serial Peripheral Interface)`
* :abbr:`UART (Universal asynchronous receiver-transmitter)`
* :abbr:`USB (Universal Serial Bus)`
* :abbr:`WDT (Watchdog Timer)`

More information about the board can be found at the `nRF52840 DK website`_.
`nRF52840 Product Specification`_ contains the processor's information
and the datasheet.


Hardware
********

nRF52840 DK has two external oscillators. The frequency of the slow clock
is 32.768 kHz. The frequency of the main clock is 32 MHz.

Supported Features
==================

.. zephyr:board-supported-hw::

See `nRF52840 DK website`_ and `nRF52840 DK Hardware guide`_
for a complete list of nRF52840 Development Kit board hardware features.

Connections and IOs
===================

LED
---

* LED1 (green) = P0.13
* LED2 (green) = P0.14
* LED3 (green) = P0.15
* LED4 (green) = P0.16

Push buttons
------------

* BUTTON1 = SW1 = P0.11
* BUTTON2 = SW2 = P0.12
* BUTTON3 = SW3 = P0.24
* BUTTON4 = SW4 = P0.25
* BOOT = SW5 = boot/reset

Programming and Debugging
*************************

.. zephyr:board-supported-runners::

Applications for the ``nrf52840dk/nrf52840`` board configuration can be
built, flashed, and debugged in the usual way. See
:ref:`build_an_application` and :ref:`application_run` for more details on
building and running.

The nRF52840 DK supports programming and debugging external boards with
nRF51 Series or nRF52 Series System on Chip (SoC)s. For more information,
see the documentation on `nRF52840 DK Debug output`_.

Flashing
========

Follow the instructions in the :ref:`nordic_segger` page to install
and configure all the necessary software. Further information can be
found in :ref:`nordic_segger_flashing`. Then build and flash
applications as usual (see :ref:`build_an_application` and
:ref:`application_run` for more details).

Here is an example for the :zephyr:code-sample:`hello_world` application.

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

.. code-block:: console

   $ minicom -D <tty_device> -b 115200

Replace :code:`<tty_device>` with the port where the board nRF52840 DK
can be found. For example, under Linux, :code:`/dev/ttyACM0`.

Then build and flash the application in the usual way.

.. zephyr-app-commands::
   :zephyr-app: samples/hello_world
   :board: nrf52840dk/nrf52840
   :goals: build flash

Debugging
=========

Refer to the :ref:`nordic_segger` page to learn about debugging Nordic boards with a
Segger IC.


Testing the LEDs and buttons in the nRF52840 DK
***********************************************

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

.. code-block:: console

   samples/basic/blinky
   samples/basic/button

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
:zephyr_file:`boards/nordic/nrf52840dk/nrf52840dk_nrf52840.dts`.

Changing UART1 pins
*******************

The following approach can be used when an application needs to use another set
of pins for UART1:

1. Add devicetree overlay file to the main directory of your application:

   .. code-block:: devicetree

      &pinctrl {
         uart1_default_alt: uart1_default_alt {
            group1 {
               psels = <NRF_PSEL(UART_TX, 0, 14)>,
                       <NRF_PSEL(UART_RX, 0, 16)>;
            };
         };
         /* required if CONFIG_PM_DEVICE=y */
         uart1_sleep_alt: uart1_sleep_alt {
            group1 {
               psels = <NRF_PSEL(UART_TX, 0, 14)>,
                       <NRF_PSEL(UART_RX, 0, 16)>;
               low-power-enable;
            };
         };
      };

      &uart1 {
        pinctrl-0 = <&uart1_default_alt>;
        /* if sleep state is not used, use /delete-property/ pinctrl-1; and
         * skip the "sleep" entry.
         */
        pinctrl-1 = <&uart1_sleep_alt>;
        pinctrl-names = "default", "sleep";
      };

   In the overlay file above, pin P0.16 is used for RX and P0.14 is used for TX

See :ref:`set-devicetree-overlays` for further details.

Selecting the pins
==================

Pins can be configured in the board pinctrl file. To see the available mappings,
open the `nRF52840 Product Specification`_, chapter 7 'Hardware and Layout'.
In the table 7.1.1 'aQFN73 ball assignments' select the pins marked
'General purpose I/O'.  Note that pins marked as 'low frequency I/O only' can only be used
in under-10KHz applications. They are not suitable for 115200 speed of UART.

.. _nrf52840dk_nrf52811:

nRF52811 emulation on nRF52840 DK
*********************************

The ``nrf52840dk/nrf52811`` board variant is a modified version of the
:zephyr:board:`nrf52840dk` that enforces the limitations imposed by the nRF52811
IC, which is a variant of the original nRF52840. Since Nordic does not offer a
development kit for the nRF52811 you can use this board to develop for this IC
while using the nRF52840 Development Kit (PCA10056).

See `nRF52811 website`_ for the official reference on the IC itself.

References
**********

.. target-notes::

.. _nRF52840 DK website: https://www.nordicsemi.com/Software-and-Tools/Development-Kits/nRF52840-DK
.. _nRF52840 Product Specification: https://docs.nordicsemi.com/bundle/ps_nrf52840/page/keyfeatures_html5.html
.. _nRF52840 DK Hardware guide: https://docs.nordicsemi.com/bundle/ug_nrf52840_dk/page/UG/dk/intro.html
.. _nRF52840 DK Debug output: https://docs.nordicsemi.com/bundle/ug_nrf52840_dk/page/UG/dk/hw_debug_out.html
.. _J-Link Software and documentation pack: https://www.segger.com/jlink-software.html
.. _nRF52811 website: https://www.nordicsemi.com/Products/Low-power-short-range-wireless/nRF52811
