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<h1 class="menu-title">Real-Time Interrupt-driven Concurrency</h1>
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<div align="center"><img width="300" height="300" src="RTIC.svg"></div>
<div style="font-size: 6em; font-weight: bolder;" align="center">RTIC</div>
<h1 align="center">Real-Time Interrupt-driven Concurrency</h1>
<p align="center">A concurrency framework for building real-time systems</p>
<h1 id="preface"><a class="header" href="#preface">Preface</a></h1>
<p>This book contains user level documentation for the Real-Time Interrupt-driven Concurrency
(RTIC) framework. The API reference is available <a href="../../api/">here</a>.</p>
<p>Formerly known as Real-Time For the Masses.</p>
<!--There is a translation of this book in [Russian].-->
<!--[Russian]: ../ru/index.html-->
<p>This is the documentation of v1.0.x of RTIC; for the documentation of version</p>
<ul>
<li>v0.5.x go <a href="/0.5">here</a>.</li>
<li>v0.4.x go <a href="/0.4">here</a>.</li>
</ul>
<h2 id="is-rtic-an-rtos"><a class="header" href="#is-rtic-an-rtos">Is RTIC an RTOS?</a></h2>
<p>A common question is whether RTIC is an RTOS or not, and depending on your background the
answer may vary. From RTIC's developers point of view; RTIC is a hardware accelerated
RTOS that utilizes the NVIC in Cortex-M MCUs to perform scheduling, rather than the more
classical software kernel.</p>
<p>Another common view from the community is that RTIC is a concurrency framework as there
is no software kernel and that it relies on external HALs.</p>
<hr />
<p><a href="https://crates.io/crates/cortex-m-rtic"><img src="https://img.shields.io/crates/v/cortex-m-rtic" alt="crates.io" /></a>
<a href="https://docs.rs/cortex-m-rtic"><img src="https://docs.rs/cortex-m-rtic/badge.svg" alt="docs.rs" /></a>
<a href="https://rtic.rs/"><img src="https://img.shields.io/badge/web-rtic.rs-red.svg?style=flat&amp;label=book&amp;colorB=d33847" alt="book" /></a>
<a href="https://matrix.to/#/#rtic:matrix.org"><img src="https://img.shields.io/matrix/rtic:matrix.org" alt="matrix" /></a>
<a href="https://hackmd.io/@xmis9JvZT8Gvo9lOEKyZ4Q/SkBJKsjuH"><img src="https://hackmd.io/badge.svg" alt="Meeting notes" /></a></p>
<h2 id="features"><a class="header" href="#features">Features</a></h2>
<ul>
<li>
<p><strong>Tasks</strong> as the unit of concurrency <sup class="footnote-reference"><a href="#1">1</a></sup>. Tasks can be <em>event triggered</em>
(fired in response to asynchronous stimuli) or spawned by the application on
demand.</p>
</li>
<li>
<p><strong>Message passing</strong> between tasks. Specifically, messages can be passed to
software tasks at spawn time.</p>
</li>
<li>
<p><strong>A timer queue</strong> <sup class="footnote-reference"><a href="#2">2</a></sup>. Software tasks can be scheduled to run at some time
in the future. This feature can be used to implement periodic tasks.</p>
</li>
<li>
<p>Support for prioritization of tasks and, thus, <strong>preemptive multitasking</strong>.</p>
</li>
<li>
<p><strong>Efficient and data race free memory sharing</strong> through fine grained <em>priority
based</em> critical sections <sup class="footnote-reference"><a href="#1">1</a></sup>.</p>
</li>
<li>
<p><strong>Deadlock free execution</strong> guaranteed at compile time. This is a stronger
guarantee than what's provided by <a href="https://doc.rust-lang.org/std/sync/struct.Mutex.html">the standard <code>Mutex</code>
abstraction</a>.</p>
</li>
</ul>
<ul>
<li>
<p><strong>Minimal scheduling overhead</strong>. The task scheduler has minimal software
footprint; the hardware does the bulk of the scheduling.</p>
</li>
<li>
<p><strong>Highly efficient memory usage</strong>: All the tasks share a single call stack and
there's no hard dependency on a dynamic memory allocator.</p>
</li>
<li>
<p><strong>All Cortex-M devices are fully supported</strong>.</p>
</li>
<li>
<p>This task model is amenable to known WCET (Worst Case Execution Time) analysis
and scheduling analysis techniques.</p>
</li>
</ul>
<h3 id="crate-cortex-m-06-vs-07-in-rtic-05x"><a class="header" href="#crate-cortex-m-06-vs-07-in-rtic-05x">Crate <code>cortex-m</code> 0.6 vs 0.7 in RTIC 0.5.x</a></h3>
<p>The crate <code>cortex-m</code> 0.7 started using trait <code>InterruptNumber</code> for interrupts instead of <code>Nr</code> from <code>bare-metal</code>. In order to preserve backwards compatibility, RTIC 0.5.x will keep using <code>cortex-m</code> 0.6 by default. <code>cortex-m</code> 0.7 can be enabled using the feature <code>cortex-m-7</code> and disabling default features:</p>
<pre><code>cortex-m-rtic = { version = "0.5.8", default-features = false, features = ["cortex-m-7"] }
</code></pre>
<p>RTIC 1.0.0 already uses <code>cortex-m</code> 0.7 by default.</p>
<h2 id="user-documentation"><a class="header" href="#user-documentation"><a href="https://rtic.rs">User documentation</a></a></h2>
<p>Documentation for the <a href="https://rtic.rs/dev">development version</a>.</p>
<h2 id="api-reference"><a class="header" href="#api-reference"><a href="https://rtic.rs/stable/api/">API reference</a></a></h2>
<h2 id="community-provided-examples-repo"><a class="header" href="#community-provided-examples-repo"><a href="https://github.com/rtic-rs/rtic-examples">Community provided examples repo</a></a></h2>
<h2 id="chat"><a class="header" href="#chat">Chat</a></h2>
<p>Join us and talk about RTIC in the <a href="https://matrix.to/#/#rtic:matrix.org">Matrix room</a>.</p>
<p>Weekly meeting notes can be found over at <a href="https://hackmd.io/@xmis9JvZT8Gvo9lOEKyZ4Q/SkBJKsjuH">HackMD</a></p>
<h2 id="contributing"><a class="header" href="#contributing">Contributing</a></h2>
<p>New features and big changes should go through the RFC process in the
<a href="https://github.com/rtic-rs/rfcs">dedicated RFC repository</a>.</p>
<h2 id="running-tests-locally"><a class="header" href="#running-tests-locally">Running tests locally</a></h2>
<p>To check all <code>Run-pass tests</code> locally on your <code>thumbv6m-none-eabi</code> or <code>thumbv7m-none-eabi</code> target device, run</p>
<pre><code class="language-console">$ cargo xtask --target &lt;your target&gt;
# ˆˆˆˆˆˆˆˆˆˆˆˆ
# e.g. thumbv7m-none-eabi
</code></pre>
<h2 id="acknowledgments"><a class="header" href="#acknowledgments">Acknowledgments</a></h2>
<p>This crate is based on the <a href="http://www.rtfm-lang.org/">Real-Time For the Masses language</a>
created by the Embedded Systems group at <a href="https://www.ltu.se/?l=en">Luleå University of Technology</a>,
led by <a href="https://www.ltu.se/staff/p/pln-1.11258?l=en">Prof. Per Lindgren</a>.</p>
<h2 id="references"><a class="header" href="#references">References</a></h2>
<div class="footnote-definition" id="1"><sup class="footnote-definition-label">1</sup>
<p>Eriksson, J., Häggström, F., Aittamaa, S., Kruglyak, A., &amp; Lindgren, P.
(2013, June). Real-time for the masses, step 1: Programming API and static
priority SRP kernel primitives. In Industrial Embedded Systems (SIES), 2013
8th IEEE International Symposium on (pp. 110-113). IEEE.</p>
</div>
<div class="footnote-definition" id="2"><sup class="footnote-definition-label">2</sup>
<p>Lindgren, P., Fresk, E., Lindner, M., Lindner, A., Pereira, D., &amp; Pinho,
L. M. (2016). Abstract timers and their implementation onto the arm cortex-m
family of mcus. ACM SIGBED Review, 13(1), 48-53.</p>
</div>
<h2 id="license"><a class="header" href="#license">License</a></h2>
<p>All source code (including code snippets) is licensed under either of</p>
<ul>
<li>Apache License, Version 2.0 (<a href="LICENSE-APACHE">LICENSE-APACHE</a> or
<a href="https://www.apache.org/licenses/LICENSE-2.0">https://www.apache.org/licenses/LICENSE-2.0</a>)</li>
<li>MIT license (<a href="LICENSE-MIT">LICENSE-MIT</a> or
<a href="https://opensource.org/licenses/MIT">https://opensource.org/licenses/MIT</a>)</li>
</ul>
<p>at your option.</p>
<p>The written prose contained within the book is licensed under the terms of the
Creative Commons CC-BY-SA v4.0 license (<a href="LICENSE-CC-BY-SA">LICENSE-CC-BY-SA</a> or
<a href="https://creativecommons.org/licenses/by-sa/4.0/legalcode">https://creativecommons.org/licenses/by-sa/4.0/legalcode</a>).</p>
<h3 id="contribution"><a class="header" href="#contribution">Contribution</a></h3>
<p>Unless you explicitly state otherwise, any contribution intentionally submitted
for inclusion in the work by you, as defined in the Apache-2.0 license, shall be
licensed as above, without any additional terms or conditions.</p>
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