.. _rak4631_nrf52840:

RAK4631
#######

Overview
********

RAK4631 is a WisBlock Core module for RAK WisBlock.
It extends the WisBlock series with a powerful
Nordic nRF52840 MCU that supports Bluetooth 5.0
(Bluetooth Low Energy) and the newest LoRa transceiver
from Semtech, the SX1262. The Semtech SX1262 has compared
to the older SX127x series a lower power consumption at
the same TX power. This makes the RAK4631 an ultra-low
power communication solution. RAK4631 can be comfortably
programmed with ZephyrRTOS.

.. image:: img/rak4631-front-parts.jpg
     :align: center
     :alt: RAK4631-NRF52840

Hardware
********

To use a RAK4631, you need at least a WisBlock Base
to plug the module in. WisBlock Base is the power
supply for the RAK4631 module and has the
programming/debug interface.

- nRF52840 ARM Cortex-M4F Processor
- 64 MHz CPU clock
- 1 Micro-AB USB OTG host/device
- Semtech SX1262 low power high range LoRa transceiver
- iPEX connectors for the LORA antenna and BLE antenna.
- Multiple interfaces, I2C, UART, GPIO, ADC
- 2 user LEDs on RAK5005 mother Board
- Powered by either Micro USB, 3.7V rechargeable battery or a 5V Solar Panel Port

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

The ``rak4631/nrf52840`` board configuration supports the following 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                  |
+-----------+------------+----------------------+
| MPU       | on-chip    | arch/arm             |
+-----------+------------+----------------------+
| NVIC      | on-chip    | arch/arm             |
+-----------+------------+----------------------+
| PWM       | on-chip    | pwm                  |
+-----------+------------+----------------------+
| RADIO     | on-chip    | Bluetooth,           |
|           |            | ieee802154           |
+-----------+------------+----------------------+
| RADIO     | on-board   | LoRa (SX1262)        |
+-----------+------------+----------------------+
| RTC       | on-chip    | system clock         |
+-----------+------------+----------------------+
| SPI(M/S)  | on-chip    | spi                  |
+-----------+------------+----------------------+
| UART      | on-chip    | serial               |
+-----------+------------+----------------------+
| USB       | on-chip    | usb                  |
+-----------+------------+----------------------+
| WDT       | on-chip    | watchdog             |
+-----------+------------+----------------------+

The default board configuration can be found in
:zephyr_file:`boards/rak/rak4631/rak4631_nrf52840_defconfig`

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

LED
---

* LED1 (green) = P1.3
* LED2 (blue) = P1.4

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

The RAK4631 board shall be connected to a Segger Embedded Debugger Unit
`J-Link OB <https://www.segger.com/jlink-ob.html>`_.  This provides a debug
interface to the NRF52840 chip. You can use JLink to communicate with
the NRF52840.

Flashing
========

#. Download JLink from the Segger `JLink Downloads Page`_.  Go to the section
   "J-Link Software and Documentation Pack" and install the "J-Link Software
   and Documentation pack for Linux".  The application JLinkExe needs to be
   accessible from your path.

#. Run your favorite terminal program to listen for output.  Under Linux the
   terminal should be :code:`/dev/ttyACM0`. For example:

   .. code-block:: console

      $ minicom -D /dev/ttyACM0 -o

   The -o option tells minicom not to send the modem initialization string.
   Connection should be configured as follows:

   - Speed: 115200
   - Data: 8 bits
   - Parity: None
   - Stop bits: 1

#. Connect the RAK4631 board to your host computer using the USB debug port.
   Then build and flash the :ref:`hello_world` application.

   .. zephyr-app-commands::
      :zephyr-app: samples/hello_world
      :board: rak4631/nrf52840
      :goals: build flash

   You should see "Hello World! rak4631_nrf52840" in your terminal.

Debugging
=========

You can debug an application in the usual way.  Here is an example for the
:ref:`hello_world` application.

.. zephyr-app-commands::
   :zephyr-app: samples/hello_world
   :board: rak4631/nrf52840
   :maybe-skip-config:
   :goals: debug

References
**********

.. target-notes::

.. _RAK4631 Product Description:
    https://docs.rakwireless.com/Product-Categories/WisBlock/RAK4631/Datasheet/#overview

.. _JLink Downloads Page:
    https://www.segger.com/downloads/jlink