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<h1 class="menu-title">Real-Time Interrupt-driven Concurrency</h1>
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<h1 id="rtic-by-example"><a class="header" href="#rtic-by-example">RTIC by example</a></h1>
<p>This part of the book introduces the RTIC framework to new users by walking them through examples of increasing complexity.</p>
<p>All examples in this part of the book are part of the
<a href="https://github.com/rtic-rs/rtic/tree/master/rtic/examples">RTIC repository</a>, found in the <code>examples</code> directory.
The examples are runnable on QEMU (emulating a Cortex M3 target),
thus no special hardware required to follow along.</p>
<h2 id="running-an-example"><a class="header" href="#running-an-example">Running an example</a></h2>
<p>To run the examples with QEMU you will need the <code>qemu-system-arm</code> program.
Check <a href="https://rust-embedded.github.io/book/intro/install.html">the embedded Rust book</a> for instructions on how to set up an
embedded development environment that includes QEMU.</p>
<p>To run the examples found in <code>examples/</code> locally using QEMU:</p>
<pre><code>cargo xtask qemu
</code></pre>
<p>This runs all of the examples against the default <code>thumbv7m-none-eabi</code> device <code>lm3s6965</code>.</p>
<p>To limit which examples are being run, use the flag <code>--example &lt;example name&gt;</code>, the name being the filename of the example.</p>
<p>Assuming dependencies in place, running:</p>
<pre><code class="language-console">$ cargo xtask qemu --example locals
</code></pre>
<p>Yields this output:</p>
<pre><code class="language-console"> Finished dev [unoptimized + debuginfo] target(s) in 0.07s
Running `target/debug/xtask qemu --example locals`
INFO xtask &gt; Testing for platform: Lm3s6965, backend: Thumbv7
INFO xtask::run &gt; 👟 Build example locals (thumbv7m-none-eabi, release, "test-critical-section,thumbv7-backend", in examples/lm3s6965)
INFO xtask::run &gt; ✅ Success.
INFO xtask::run &gt; 👟 Run example locals in QEMU (thumbv7m-none-eabi, release, "test-critical-section,thumbv7-backend", in examples/lm3s6965)
INFO xtask::run &gt; ✅ Success.
INFO xtask::results &gt; ✅ Success: Build example locals (thumbv7m-none-eabi, release, "test-critical-section,thumbv7-backend", in examples/lm3s6965)
INFO xtask::results &gt; ✅ Success: Run example locals in QEMU (thumbv7m-none-eabi, release, "test-critical-section,thumbv7-backend", in examples/lm3s6965)
INFO xtask::results &gt; 🚀🚀🚀 All tasks succeeded 🚀🚀🚀
</code></pre>
<p>It is great that examples are passing and this is part of the RTIC CI setup too, but for the purposes of this book we must add the <code>--verbose</code> flag, or <code>-v</code> for short to see the actual program output:</p>
<pre><code class="language-console"> cargo xtask qemu --verbose --example locals
Finished dev [unoptimized + debuginfo] target(s) in 0.03s
Running `target/debug/xtask qemu --example locals --verbose`
DEBUG xtask &gt; Stderr of child processes is inherited: false
DEBUG xtask &gt; Partial features: false
INFO xtask &gt; Testing for platform: Lm3s6965, backend: Thumbv7
INFO xtask::run &gt; 👟 Build example locals (thumbv7m-none-eabi, release, "test-critical-section,thumbv7-backend", in examples/lm3s6965)
INFO xtask::run &gt; ✅ Success.
INFO xtask::run &gt; 👟 Run example locals in QEMU (thumbv7m-none-eabi, release, "test-critical-section,thumbv7-backend", in examples/lm3s6965)
INFO xtask::run &gt; ✅ Success.
INFO xtask::results &gt; ✅ Success: Build example locals (thumbv7m-none-eabi, release, "test-critical-section,thumbv7-backend", in examples/lm3s6965)
cd examples/lm3s6965 &amp;&amp; cargo build --target thumbv7m-none-eabi --features test-critical-section,thumbv7-backend --release --example locals
DEBUG xtask::results &gt;
cd examples/lm3s6965 &amp;&amp; cargo build --target thumbv7m-none-eabi --features test-critical-section,thumbv7-backend --release --example locals
Stderr:
Finished release [optimized] target(s) in 0.02s
INFO xtask::results &gt; ✅ Success: Run example locals in QEMU (thumbv7m-none-eabi, release, "test-critical-section,thumbv7-backend", in examples/lm3s6965)
cd examples/lm3s6965 &amp;&amp; cargo run --target thumbv7m-none-eabi --features test-critical-section,thumbv7-backend --release --example locals
DEBUG xtask::results &gt;
cd examples/lm3s6965 &amp;&amp; cargo run --target thumbv7m-none-eabi --features test-critical-section,thumbv7-backend --release --example locals
Stdout:
bar: local_to_bar = 1
foo: local_to_foo = 1
idle: local_to_idle = 1
Stderr:
Finished release [optimized] target(s) in 0.02s
Running `qemu-system-arm -cpu cortex-m3 -machine lm3s6965evb -nographic -semihosting-config enable=on,target=native -kernel target/thumbv7m-none-eabi/release/examples/locals`
Timer with period zero, disabling
INFO xtask::results &gt; 🚀🚀🚀 All tasks succeeded 🚀🚀🚀
</code></pre>
<p>Look for the content following <code>Stdout:</code> towards the end ouf the output, the program output should have these lines:</p>
<pre><code class="language-console">bar: local_to_bar = 1
foo: local_to_foo = 1
idle: local_to_idle = 1
</code></pre>
<blockquote>
<p><strong>NOTE</strong>:
For other useful options to <code>cargo xtask</code>, see:</p>
<pre><code>cargo xtask qemu --help
</code></pre>
<p>The <code>--platform</code> flag allows changing which device examples are run on,
currently <code>lm3s6965</code> is the best supported, work is ongoing to
increase support for other devices, including both ARM and RISC-V</p>
</blockquote>
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