3 Pigweed is an open source collection of embedded-targeted libraries--or as we
4 like to call them, modules. These modules are building blocks and infrastructure
5 that enable faster and more reliable development on small-footprint MMU-less
6 32-bit microcontrollers like the STMicroelectronics STM32L452 or the Nordic
9 Pigweed is in the early stages of development, **and should be considered
10 experimental**. We’re continuing to evolve the platform and add new modules. We
11 value developer feedback along the way.
15 - [Getting started guide](docs/getting_started.md)
16 - [Source code](https://pigweed.googlesource.com/pigweed/pigweed/+/refs/heads/master)
17 - [Code reviews](https://pigweed-review.googlesource.com/)
18 - [Issue tracker](https://bugs.chromium.org/p/pigweed/issues/list)
19 - [Mailing list](https://groups.google.com/forum/#!forum/pigweed)
20 - [Chat room (Discord)](https://discord.gg/M9NSeTA)
21 - [Open Source blog post](https://opensource.googleblog.com/2020/03/pigweed-collection-of-embedded-libraries.html)
23 Get the code: `git clone https://pigweed.googlesource.com/pigweed/pigweed`
27 If you'd like to get set up with Pigweed, please visit the
28 [getting started guide](docs/getting_started.md).
30 # What does Pigweed offer?
32 There are many modules in Pigweed, and this section only showcases a small
33 selection that happen to produce visual output. For more information about the
34 different Pigweed module offerings, refer to "Module Guides" section in the full
37 Note: For now the full documentation is not available online; you must build
38 it. Building the docs is easy; see the [getting started
39 guide](docs/getting_started.md) for how.
41 ## `pw_watch` - Build, flash, run, & test on save
43 In the web development space, file system watchers are prevalent. These watchers
44 trigger a web server reload on source change, making development much faster. In
45 the embedded space, file system watchers are less prevalent; however, they are
46 no less useful! The Pigweed watcher module makes it easy to instantly compile,
47 flash, and run tests upon save. Combined with the GN-based build which expresses
48 the full dependency tree, only the exact tests affected by a file change are run
51 The demo below shows `pw_watch` building for a STMicroelectronics
52 STM32F429I-DISC1 development board, flashing the board with the affected test,
53 and verifying the test runs as expected. Once this is set up, you can attach
54 multiple devices to run tests in a distributed manner to reduce the time it
57 ![pw watch running on-device tests](docs/images/pw_watch_on_device_demo.gif)
59 ## `pw_presubmit` - Vacuum code lint on every commit
61 Presubmit checks are essential tools, but they take work to set up, and projects
62 don’t always get around to it. The `pw_presubmit` module provides tools for
63 setting up high quality presubmit checks for any project. We use this framework
64 to run Pigweed’s presubmit on our workstations and in our automated building
67 The `pw_presubmit` module includes `pw format` command, a tool that provides a
68 unified interface for automatically formatting code in a variety of languages.
69 With `pw format`, you can format C, C++, Python, GN, and Go code according to
70 configurations defined by your project. `pw format` leverages existing tools
71 like `clang-format`, and it’s simple to add support for new languages.
73 ![pw presubmit demo](pw_presubmit/docs/pw_presubmit_demo.gif)
75 ## `pw_env_setup` - Cross platform embedded compiler setup
77 A classic problem in the embedded space is reducing the time from git clone to
78 having a binary executing on a device. The issue is that an entire suite of
79 tools is needed for non-trivial production embedded projects. For example:
81 - A C++ compiler for your target device, and also for your host
82 - A build system or three; for example, GN, Ninja, CMake, Bazel
83 - A code formatting program like clang-format
84 - A debugger like OpenOCD to flash and debug your embedded device
85 - A known Python version with known modules installed for scripting
86 - A Go compiler for the Go-based command line tools
89 In the server space, container solutions like Docker or Podman solve this;
90 however, in our experience container solutions are a mixed bag for embedded
91 systems development where one frequently needs access to native system resources
92 like USB devices, or must operate on Windows.
94 `pw_env_setup` is our compromise solution for this problem that works on Mac,
95 Windows, and Linux. It leverages the Chrome packaging system CIPD to bootstrap a
96 Python installation, which in turn inflates a virtual environment. The tooling
97 is installed into your workspace, and makes no changes to your system. This
98 tooling is designed to be reused by any project.
100 ![pw environment setup demo](docs/images/pw_env_setup_demo.gif)
102 ## `pw_unit_test` - Embedded testing for MCUs
104 Unit testing is important, and Pigweed offers a portable library that’s broadly
105 compatible with [Google Test](https://github.com/google/googletest). Unlike
106 Google Test, `pw_unit_test` is built on top of embedded friendly primitives; for
107 example, it does not use dynamic memory allocation. Additionally, it is easy to
108 port to new target platforms by implementing the
109 [test event handler interface](https://pigweed.googlesource.com/pigweed/pigweed/+/refs/heads/master/pw_unit_test/public/pw_unit_test/event_handler.h).
111 Like other modules in Pigweed, `pw_unit_test` is designed for use in
112 established codebases with their own build system, without the rest of Pigweed
113 or the Pigweed integrated GN build. However, when combined with Pigweed's
114 build, the result is a flexible and powerful setup that enables easily
115 developing code on your desktop (with tests), then running the same tests
118 ![pw_status test run natively on host](docs/images/pw_status_test.png)
122 See the "Module Guides" in the documentation for the complete list and
123 documentation for each, but is a selection of some others:
125 - `pw_cpu_exception_cortex_m`: Robust low level hardware fault handler for ARM
126 Cortex-M; the handler even has unit tests written in assembly to verify
127 nested-hardware-fault handling!
129 - `pw_polyfill`: Similar to JavaScript “polyfill” libraries, this module
130 provides selected C++17 standard library components that are compatible with
133 - `pw_minimal_cpp_stdlib`: An entirely incomplete implementation of the C++17
134 standard library, that provides some of the primitives needed by Pigweed
135 itself. Useful for projects that want to use Pigweed, but don’t enable the
136 typical standard C++ libraries like GNU’s libstdc++ or LLVM’s libc++. Don’t
137 use this module unless you know what you are doing.
139 - `pw_tokenizer`: Replace string literals from log statements with 32-bit
140 tokens, to reduce flash use, reduce logging bandwidth, and save formatting
141 cycles from log statements at runtime.
143 - `pw_kvs`: A key-value-store implementation for flash-backed persistent
144 storage with integrated wear levelling. This is a lightweight alternative to
145 a file system for embedded devices.
147 - `pw_protobuf`: An early preview of our wire-format-oriented protocol buffer
148 implementation. This protobuf compiler makes a different set of
149 implementation tradeoffs than the most popular protocol buffer library in