.. _docs-release-notes-2022-jan:

===================================
Pigweed: What's New in January 2022
===================================
Happy new year from the Pigweed team! We’re excited to share what we’ve been up
to this month and we’re really looking forward to what 2022 will bring to the
Pigweed community.

:ref:`Pigweed<docs-root>` is a collection of libraries and tools for building
robust embedded software, efficiently. Pigweed allows you to write code that
runs transparently on both your host machine and tiny 32-bit microcontrollers
like those in the :ref:`STM32<target-stm32f429i-disc1>` and
:ref:`Arduino<target-arduino>` families, while giving you the comforts of modern
software development traditionally lacking in embedded systems, like
:ref:`easy unit testing<module-pw_unit_test>`,
:ref:`powerful build systems<docs-build-system>`,
:ref:`flexible logging<module-pw_log>`, and
:ref:`reliable communication<module-pw_rpc>`.

.. admonition:: Note
   :class: warning

   Many Pigweed modules are already shipping in commercial products, but it is
   still an early access project. Find out if
   :ref:`Pigweed is right for you<docs-concepts-right-for-my-project>`.

Pigweed is a free and open source project and we welcome contributions! Join us
on `Discord <https://discord.gg/M9NSeTA>`_ to share feedback, ask questions, and
get involved with the Pigweed community!

------------------------------
Experimental Pigweed framework
------------------------------
.. admonition:: tl;dr
   :class: checkmark

   We’re starting the “whole OS” framework version of Pigweed! It’s not ready
   for use yet but you might want to take a peek.

Pigweed is designed to be highly modular—you can use as many or as few of the
Pigweed modules as you need for your project, and those modules will work
flexibly in any project structure. This works great when you want to add Pigweed
super powers like hybrid host/target unit testing or RPC communication to an
existing project. While Pigweed gives you nearly all of the tools you need to
efficiently build a robust, reliable embedded project, until now we haven’t had
a great solution for building a new project on Pigweed.

The Pigweed framework assembles an opinionated project structure, build system,
and development environment that does three key things:

* Takes care of difficult but unproductive project plumbing issues like setting
  up a target toolchain and providing support for
  :ref:`OS abstractions<docs-os_abstraction_layers>`.

* Configures Pigweed module backends that give you logging, asserts, threads,
  dynamic memory allocation, and more, that work transparently both on host and
  on target

* Sets up a productive development environment with rich code analysis and
  powerful device interaction tools

You can experiment with this right now by checking out the ``pw_system``
:ref:`documentation<module-pw_system>`. The experimental configuration leverages
FreeRTOS and runs on the STM32F429I Discovery board. With a
:ref:`few simple commands<target-stm32f429i-disc1-stm32cube>`, you can have a
complete embedded development environment set up and focus on building your
product.

.. warning::

   The Pigweed framework is still in very active development and you should
   expect breaking changes in the future. If you’re experimenting with it, we
   would love to hear from you! Join us on
   `Discord <https://discord.gg/M9NSeTA>`_!

-------------------------------------
Support for plugins in ``pw_console``
-------------------------------------
Teams that use Pigweed quickly come to rely on the
:ref:`console<module-pw_console>` as a vital tool for interacting with their
devices via RPC. It’s now possible to tailor the console to meet your project’s
specific needs through a new :ref:`plugin interface<module-pw_console-plugins>`.
You can build your own menus, window panes, keybindings, and clickable buttons
to truly make ``pw_console`` your own.

How are you using the Pigweed console in your project? Let us know on
`Discord <https://discord.gg/M9NSeTA>`_!

------------------------------------
Expanded support for Bazel and CMake
------------------------------------
Pigweed’s primary build system is
`GN (Generate Ninja) <https://gn.googlesource.com/gn>`_, but to make it easier
to use Pigweed modules in existing projects, we have been expanding support for
the `Bazel <https://bazel.build/>`_ and `CMake <https://cmake.org/>`_ build
systems. Right now, the best way to determine which build systems a module
supports is to look out for ``BUILD.gn``, ``BUILD.bazel`` and ``CMakeLists.txt``
files (respectively) in module directories. While we work on improving build
system support and documentation, check out the
:ref:`build system documentation<docs-build-system>` for more detailed
information and join us on Discord for support.

----------------------------------------
Changes to the RPC ``ChannelOutput`` API
----------------------------------------
RPC endpoints use :ref:`ChannelOutput<module-pw_rpc-ChannelOutput>` instances to
send packets encoding RPC data. To send an encoded RPC packet, we need a buffer
containing the packet’s data. In the past, we could request a buffer by doing
something like this:

.. code-block:: cpp

   auto buffer = pw::rpc::ChannelOutput::AcquireBuffer(buffer_size)
   // fill in the buffer here
   pw::rpc::ChannelOutput::SendAndReleaseBuffer(buffer)

The ``ChannelOutput::AcquireBuffer`` and ``ChannelOutput::SendAndReleaseBuffer``
methods are no longer part of ``ChannelOutput``’s public API, making its
internal buffer private. Now, we create our own buffer and ``ChannelOutput`` is
simply responsible for sending it:

.. code-block:: cpp

   auto buffer = ... // create your own local buffer with RPC packet data
   pw::rpc::ChannelOutput::Send(buffer)

This approach avoids several tricky concurrency issues related to buffer
lifetimes, and simplifies the ``ChannelOutput`` API. It also opens up the
possibility of projects managing RPC buffers in more flexible ways, e.g. via
dynamically-allocated memory or separate shared memory mechanisms.

.. warning::

   This is a breaking change if you update pw_rpc, but one that can be fixed
   quickly.

We’re actively reviewing the RPC API with a view towards significantly improving
it in the future. Share your input with us on
`Discord <https://discord.gg/M9NSeTA>`_!

------------
More Updates
------------
* It’s now possible to generate a token database from a list of strings in a
  JSON file for ``pw_tokenizer``. This can be useful when you need to tokenize
  strings that can’t be parsed from compiled binaries.

* ``pw_assert``‘s new ``pw_assert_tokenized`` backend provides a much more
  space-efficient implementation compared to using ``pw_assert_log`` with
  ``pw_log_tokenized``. However, there are trade offs to consider, so check out
  the :ref:`documentation<module-pw_assert_tokenized>`.

* CMake builds now support compile-time module configuration similar to GN
  through the use of the ``pw_add_module_config`` and ``pw_set_module_config``
  functions.

* In ``pw_build``, it is now possible to set a specific working directory for
  :ref:`pw_exec<module-pw_build-pw_exec>` actions.

* ``pw_cpu_exception`` now supports the ARMv8M Mainline architecture in
  ``pw_cpu_exception_cortex_m``. This allows us to take advantage of stack limit
  boundary features in microcontrollers using that architecture, like Cortex M33
  and M35P.

------------
Get Involved
------------
.. tip::

   We welcome contributions from the community! Here are just a few
   opportunities to get involved.

* Pigweed now includes GN build files for
  `TinyUSB <https://github.com/hathach/tinyusb>`_, a popular USB library for
  embedded systems. Projects can now include it by cloning the TinyUSB
  repository and configuring GN to build it. But right now, we lack interfaces
  between TinyUSB and Pigweed abstractions like pw_stream. This is a great
  opportunity to help get very useful functionality across the finish line.

* We’re very interested in supporting the
  `Raspberry Pi Pico <https://www.raspberrypi.com/products/raspberry-pi-pico/>`_
  and the ecosystem of devices using the RP2040 microcontroller. We will be
  working in earnest on this in the coming months and welcome anyone who wants
  to lend a helping hand!

* Evolving the Pigweed framework from its current experimental state to a
  relatively complete embedded project platform is one of our major focuses this
  year, and we want your help. That help can range from providing input on what
  you’re looking for in a framework, to building small projects with it and
  providing feedback, up to contributing directly to its development. Join us to
  talk about it on `Discord <https://discord.gg/M9NSeTA>`_!