.. _nrf9131ek_nrf9131:

nRF9131 EK
##########

Overview
********

The nRF9131 EK (PCA10165) is a single-board evaluation kit for the nRF9131 SiP
for DECT NR+ and LTE-M/NB-IoT with GNSS.
The nrf9131ek_nrf9131 board configuration provides support for the Nordic Semiconductor nRF9131 ARM
Cortex-M33F CPU with ARMv8-M Security Extension 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)`
* :abbr:`RTC (nRF RTC System Clock)`
* Segger RTT (RTT Console)
* :abbr:`SPI (Serial Peripheral Interface)`
* :abbr:`UARTE (Universal asynchronous receiver-transmitter with EasyDMA)`
* :abbr:`WDT (Watchdog Timer)`
* :abbr:`IDAU (Implementation Defined Attribution Unit)`

.. figure:: img/nrf9131ek_nrf9131.webp
     :align: center
     :alt: nRF9131 EK

     nRF9131 EK (Credit: Nordic Semiconductor)

The `Nordic Semiconductor Infocenter`_
contains the processor's information and the datasheet.


Hardware
********

nRF9131 EK 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
==================

The nrf9131ek_nrf9131 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                  |
+-----------+------------+----------------------+
| RTC       | on-chip    | system clock         |
+-----------+------------+----------------------+
| RTT       | Segger     | console              |
+-----------+------------+----------------------+
| SPI(M/S)  | on-chip    | spi                  |
+-----------+------------+----------------------+
| SPU       | on-chip    | system protection    |
+-----------+------------+----------------------+
| UARTE     | on-chip    | serial               |
+-----------+------------+----------------------+
| WDT       | on-chip    | watchdog             |
+-----------+------------+----------------------+

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

LED
---

* LED (red) = P0.29
* LED (green) = P0.30
* LED (blue) = P0.31

Push buttons and Switches
-------------------------

* BUTTON = P0.28
* RESET

Security components
===================

- Implementation Defined Attribution Unit (`IDAU`_).  The IDAU is implemented
  with the System Protection Unit and is used to define secure and non-secure
  memory maps.  By default, all of the memory space  (Flash, SRAM, and
  peripheral address space) is defined to be secure accessible only.
- Secure boot.


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

nrf9131ek_nrf9131 supports the Armv8m Security Extension, and by default boots
in the Secure state.

Building Secure/Non-Secure Zephyr applications with Arm |reg| TrustZone |reg|
=============================================================================

Applications on the nRF9131 may contain a Secure and a Non-Secure firmware
image. The Secure image can be built using either Zephyr or
`Trusted Firmware M`_ (TF-M). Non-Secure firmware images are always built
using Zephyr. The two alternatives are described below.

.. note::

   By default the Secure image for nRF9131 is built using TF-M.

Building the Secure firmware using Zephyr
-----------------------------------------

The process requires the following steps:

1. Build the Secure Zephyr application using ``-DBOARD=nrf9131ek_nrf9131`` and
   ``CONFIG_TRUSTED_EXECUTION_SECURE=y`` in the application project configuration file.
2. Build the Non-Secure Zephyr application using ``-DBOARD=nrf9131ek_nrf9131_ns``.
3. Merge the two binaries together.

Building the Secure firmware with TF-M
--------------------------------------

The process to build the Secure firmware image using TF-M and the Non-Secure
firmware image using Zephyr requires the following action:

1. Build the Non-Secure Zephyr application
   using ``-DBOARD=nrf9131ek_nrf9131_ns``.
   To invoke the building of TF-M the Zephyr build system requires the
   Kconfig option ``BUILD_WITH_TFM`` to be enabled, which is done by
   default when building Zephyr as a Non-Secure application.
   The Zephyr build system will perform the following steps automatically:

      * Build the Non-Secure firmware image as a regular Zephyr application
      * Build a TF-M (secure) firmware image
      * Merge the output binaries together
      * Optionally build a bootloader image (MCUboot)

.. note::

   Depending on the TF-M configuration, an application DTS overlay may be
   required, to adjust the Non-Secure image Flash and SRAM starting address
   and sizes.

When building a Secure/Non-Secure application, the Secure application will
have to set the IDAU (SPU) configuration to allow Non-Secure access to all
CPU resources utilized by the Non-Secure application firmware. SPU
configuration shall take place before jumping to the Non-Secure application.

Building a Secure only application
==================================

Build the Zephyr app in the usual way (see :ref:`build_an_application`
and :ref:`application_run`), using ``-DBOARD=nrf9131ek_nrf9131``.


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 :ref:`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 nRF9131 EK
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: nrf9131ek_nrf9131
   :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 nRF9131 EK
**********************************************

There are 2 samples that allow you to test that the button and LED on
the board are working properly with Zephyr:

* :zephyr:code-sample:`blinky`
* :zephyr:code-sample:`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/arm/nrf9131ek_nrf9131/nrf9131ek_nrf9131_common.dtsi`.

References
**********

.. target-notes::

.. _IDAU:
   https://developer.arm.com/docs/100690/latest/attribution-units-sau-and-idau
.. _Nordic Semiconductor Infocenter: https://infocenter.nordicsemi.com
.. _Trusted Firmware M: https://www.trustedfirmware.org/projects/tf-m/