.. _getting_started:

Getting Started Guide
#####################

Use this guide to get started with your :ref:`Zephyr <introducing_zephyr>`
development.

Checking Out the Source Code Anonymously
****************************************

The Zephyr source code is hosted in a GitHub repo that supports
anonymous cloning via git. There are scripts and such in this repo that
you'll need to set up your development environment, and we'll be using
Git to get this repo.  (If you don't have Git installed, see the
beginning of the OS-specific instructions below for help.)

We'll begin by
using Git to clone the repository anonymously. Enter:

.. code-block:: console

   # On Linux/macOS
   cd ~
   # On Windows
   cd %userprofile%

   git clone https://github.com/zephyrproject-rtos/zephyr.git

You have successfully checked out a copy of the source code to your local
machine in a ``zephyr`` folder in your home directory.

.. _getting_started_cmake:

A brief note on the Zephyr build system
***************************************

The Zephyr project uses `CMake`_ as a tool for managing the building of the
project. CMake is able to generate build files in different formats (also
known as "generators"), and the following ones are currently supported
by Zephyr:

 * ``make``: Supported on UNIX-like platforms (Linux, macOS).
 * ``ninja``: Supported on all platforms.

Most of the examples in the Zephyr documentation use ``ninja`` as a build tool,
but you should be able to use any generator on any of the examples listed.

Set Up the Development Environment
**********************************

The Zephyr project supports these operating systems:

* Linux
* macOS
* Microsoft Windows

Use the following procedures to create a new development environment.

.. toctree::
   :maxdepth: 1

   installation_linux.rst
   installation_mac.rst
   installation_win.rst


.. _getting_started_run_sample:

Building and Running an Application
***********************************

Next, build a sample Zephyr application. You can then run it either in
emulation or using POSIX APIs available on your host.

If your board is supported by Zephyr (see :ref:`boards` for a list),
consult its documentation for flashing and running instructions.

Building a Sample Application
=============================

Follow these steps to build the :ref:`hello_world` sample application
provided with Zephyr.

#. Navigate to the main project directory:

   .. code-block:: console

      cd zephyr

#. Set up your build environment:

   .. code-block:: console

      # On Linux/macOS
      source zephyr-env.sh
      # On Windows
      zephyr-env.cmd

#. Build the :ref:`hello_world` example for the `arduino_101` board, enter:

   .. zephyr-app-commands::
      :zephyr-app: samples/hello_world
      :board: arduino_101
      :build-dir: arduino_101
      :goals: build

   On Linux/macOS you can also build with ``make`` instead of ``ninja``:

   .. zephyr-app-commands::
      :zephyr-app: samples/hello_world
      :generator: make
      :host-os: unix
      :board: arduino_101
      :build-dir: arduino_101
      :goals: build

You can build for a different board by defining the variable BOARD
with another of the supported boards, for example:

   .. zephyr-app-commands::
      :zephyr-app: samples/hello_world
      :board: arduino_due
      :build-dir: arduino_due
      :goals: build

For further information on the supported boards go see
:ref:`here <boards>`. Alternatively, run the following command to obtain a list
of the supported boards:

.. code-block:: console

   ninja usage

Sample projects for different features of the project are available at
at :file:`ZEPHYR_BASE/samples`.
After building an application successfully, the results can be found in the
directory where cmake was invoked.

The ELF binaries generated by the build system are named by default
:file:`zephyr.elf`. This value can be overridden in the application
configuration The build system generates different names for different use cases
depending on the hardware and boards used.

.. _sdkless_builds:

Building without the Zephyr SDK
===============================

The Zephyr SDK is provided for convenience and ease of use. It provides
cross-compilers for all ports supported by the Zephyr OS and does not require
any extra flags when building applications or running tests. In addition to
cross-compilers, the Zephyr SDK also provides prebuilt host tools.

It is, however, possible to build without the SDK.  If you are using 3rd party
cross compilers, jump forward to `Using 3rd Party Cross Compilers`_ for
details.  A "3rd party cross compiler" is a toolchain that the Zephyr build
system already knows about, such as `GNU ARM Embedded`_ that we use in this
document.

If you are going to use custom compilers, check `Using Custom Cross Compilers`_
for more detail.  A "custom compiler" would be the one your Linux distribution
packaged, the one you compiled on your own, or the one you downloaded from the
net.  The Zephyr build system doesn't know about them and doesn't officially
support them.

As already noted above, the SDK also includes prebuilt host tools.  To use the
SDK's prebuilt host tools alongside a 3rd party or custom cross-compiler, keep
the ZEPHYR_SDK_INSTALL_DIR environment variable set to the Zephyr SDK
installation directory. To build without the Zephyr SDK's prebuilt host tools,
the ZEPHYR_SDK_INSTALL_DIR environment variable must be unset

Follow the steps below to build without the Zephyr SDK:

   .. code-block:: console

      # On Linux/macOS
      unset ZEPHYR_SDK_INSTALL_DIR
      cd <zephyr git clone location>
      source zephyr-env.sh
      # On Windows
      set ZEPHYR_SDK_INSTALL_DIR=
      cd <zephyr git clone location>
      zephyr-env.cmd

.. _third_party_x_compilers:

Using 3rd Party Cross Compilers
===============================

To use a 3rd party cross compiler that is not provided by the Zephyr
SDK, follow the steps below.

#. We will use the `GNU ARM Embedded`_ compiler for this example, download the
   package suitable for your operating system from the `GNU ARM Embedded`_ website
   and extract it on your file system. This example assumes the compiler was
   extracted to: :file:`<user folder>/gcc-arm-none-eabi-7-2018-q2-update/`.

#. Build the example :ref:`hello_world` project, enter:

   .. code-block:: console

      # On Linux/macOS
      export GNUARMEMB_TOOLCHAIN_PATH="~/gcc-arm-none-eabi-7-2018-q2-update/"
      export ZEPHYR_TOOLCHAIN_VARIANT=gnuarmemb
      # On Windows
      set GNUARMEMB_TOOLCHAIN_PATH="%userprofile%\gcc-arm-none-eabi-7-2018-q2-update\"
      set ZEPHYR_TOOLCHAIN_VARIANT=gnuarmemb

   .. zephyr-app-commands::
      :zephyr-app: samples/hello_world
      :board: arduino_due
      :goals: build

Make sure to unset the ZEPHYR_SDK_INSTALL_DIR if you don't use the
SDK's host tools. See `Building without the Zephyr SDK`_ for details.

It is possible to use the Zephyr SDK's host tools along with a 3rd
party cross compiler. To do that, keep the ZEPHYR_SDK_INSTALL_DIR
environment variable set to the Zephyr SDK installation directory.
See `Set Up the Development Environment`_ for more details on the
ZEPHYR_SDK_INSTALL_DIR environment variable.

Using Custom Cross Compilers
============================

To use a custom cross compiler, follow the steps below.

#. Install a cross compiler suitable for your system. We will use the
   gcc-arm-none-eabi compiler on Debian system for this example.

   .. code-block:: console

      # On Debian or Ubuntu
      sudo apt-get install gcc-arm-none-eabi
      # On Fedora or Red hat
      sudo dnf install arm-none-eabi-newlib

#. Build the example :ref:`hello_world` project, enter:

   .. code-block:: console

      # On Linux
      unset GNUARMEMB_TOOLCHAIN_PATH
      export ZEPHYR_TOOLCHAIN_VARIANT=cross-compile
      export CROSS_COMPILE=/usr/bin/arm-none-eabi-

   .. zephyr-app-commands::
      :zephyr-app: samples/hello_world
      :board: arduino_zero
      :goals: build

Note that the Zephyr build system assumes that all the tools within your
toolchain used to compile and link your code, reside in the same directory and
have a common prefix.  Set the ``CROSS_COMPILE`` environment variable to the
path of your toolchain's location and that common prefix. In the example above,
gcc-arm-none-eabi is installed in ``/usr/bin/`` with the common prefix of
``arm-none-eabi-``.  If your toolchain is at ``/opt/mytoolchain/bin`` with the
prefix of ``myarch-none-elf-``, it would be
``CROSS_COMPILE=/opt/mytoolchain/bin/arch-none-elf-``.

Make sure to unset the ZEPHYR_SDK_INSTALL_DIR if you don't use the SDK's host
tools. See `Building without the Zephyr SDK`_ and `Set Up the Development
Environment`_ for more details.

Running a Sample Application in QEMU
====================================

To perform rapid testing of an application in the development environment you
can use the QEMU emulation board configuration available for both X86 and ARM
Cortex-M3 architectures. This can be easily accomplished by calling a special
target when building an application that invokes QEMU once the build process is
completed.

To run an application using the x86 emulation board configuration (qemu_x86),
type:

.. zephyr-app-commands::
   :zephyr-app: samples/hello_world
   :host-os: unix
   :board: qemu_x86
   :goals: build run

To exit the qemu emulator, press ``Ctrl-a``, followed by ``x``.

Use the ``qemu_cortex_m3`` board configuration to test the ARM build.

QEMU is not supported on all boards and SoCs. When developing for a specific
hardware target you should always test on the actual hardware and should not
rely on testing in the QEMU emulation environment only.

Running a Sample Application natively (POSIX OS)
================================================

It is also possible to compile some of the sample and test applications to run
as native process on a POSIX OS (e.g. Linux).
To be able to do this, remember to have installed the 32 bit libC if your OS is
natively 64bit. See the :ref:`native_posix` section on host dependencies
for more information.

To compile and run an application in this way, type:

.. zephyr-app-commands::
   :zephyr-app: samples/hello_world
   :host-os: unix
   :board: native_posix
   :goals: build

and then:

.. code-block:: console

   ninja run

   # or just:
   zephyr/zephyr.exe
   # Press Ctrl+C to exit

You can run ``zephyr/zephyr.exe --help`` to get a list of available
options.  See the :ref:`native_posix` document for more information.

This executable can be instrumented like any other Linux process. For ex. with gdb
or valgrind.
Note that the native port is currently only tested in Linux.

.. _GNU ARM Embedded: https://developer.arm.com/open-source/gnu-toolchain/gnu-rm
.. _CMake: https://cmake.org