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<h1 class="menu-title">Real-Time Interrupt-driven Concurrency</h1>
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<h1 id="the-app-attribute-and-an-rtic-application"><a class="header" href="#the-app-attribute-and-an-rtic-application">The <code>#[app]</code> attribute and an RTIC application</a></h1>
<h2 id="requirements-on-the-app-attribute"><a class="header" href="#requirements-on-the-app-attribute">Requirements on the <code>app</code> attribute</a></h2>
<p>All RTIC applications use the <a href="../../../api/cortex_m_rtic_macros/attr.app.html"><code>app</code></a> attribute (<code>#[app(..)]</code>). This attribute
only applies to a <code>mod</code>-item containing the RTIC application. The <code>app</code>
attribute has a mandatory <code>device</code> argument that takes a <em>path</em> as a value.
This must be a full path pointing to a
<em>peripheral access crate</em> (PAC) generated using <a href="https://crates.io/crates/svd2rust"><code>svd2rust</code></a> <strong>v0.14.x</strong> or
newer.</p>
<p>The <code>app</code> attribute will expand into a suitable entry point and thus replaces
the use of the <a href="../../../api/cortex_m_rt_macros/attr.entry.html"><code>cortex_m_rt::entry</code></a> attribute.</p>
<h2 id="an-rtic-application-example"><a class="header" href="#an-rtic-application-example">An RTIC application example</a></h2>
<p>To give a flavour of RTIC, the following example contains commonly used features.
In the following sections we will go through each feature in detail.</p>
<pre><pre class="playground"><code class="language-rust"><span class="boring">#![allow(unused)]
</span><span class="boring">fn main() {
</span>//! examples/common.rs
#![deny(unsafe_code)]
#![deny(warnings)]
#![deny(missing_docs)]
#![no_main]
#![no_std]
use panic_semihosting as _;
#[rtic::app(device = lm3s6965, dispatchers = [SSI0, QEI0])]
mod app {
use cortex_m_semihosting::{debug, hprintln};
use systick_monotonic::*; // Implements the `Monotonic` trait
// A monotonic timer to enable scheduling in RTIC
#[monotonic(binds = SysTick, default = true)]
type MyMono = Systick&lt;100&gt;; // 100 Hz / 10 ms granularity
// Resources shared between tasks
#[shared]
struct Shared {
s1: u32,
s2: i32,
}
// Local resources to specific tasks (cannot be shared)
#[local]
struct Local {
l1: u8,
l2: i8,
}
#[init]
fn init(cx: init::Context) -&gt; (Shared, Local, init::Monotonics) {
let systick = cx.core.SYST;
// Initialize the monotonic (SysTick rate in QEMU is 12 MHz)
let mono = Systick::new(systick, 12_000_000);
// Spawn the task `foo` directly after `init` finishes
foo::spawn().unwrap();
// Spawn the task `bar` 1 second after `init` finishes, this is enabled
// by the `#[monotonic(..)]` above
bar::spawn_after(1.secs()).unwrap();
debug::exit(debug::EXIT_SUCCESS); // Exit QEMU simulator
(
// Initialization of shared resources
Shared { s1: 0, s2: 1 },
// Initialization of task local resources
Local { l1: 2, l2: 3 },
// Move the monotonic timer to the RTIC run-time, this enables
// scheduling
init::Monotonics(mono),
)
}
// Background task, runs whenever no other tasks are running
#[idle]
fn idle(_: idle::Context) -&gt; ! {
loop {
continue;
}
}
// Software task, not bound to a hardware interrupt.
// This task takes the task local resource `l1`
// The resources `s1` and `s2` are shared between all other tasks.
#[task(shared = [s1, s2], local = [l1])]
fn foo(_: foo::Context) {
// This task is only spawned once in `init`, hence this task will run
// only once
hprintln!("foo");
}
// Software task, also not bound to a hardware interrupt
// This task takes the task local resource `l2`
// The resources `s1` and `s2` are shared between all other tasks.
#[task(shared = [s1, s2], local = [l2])]
fn bar(_: bar::Context) {
hprintln!("bar");
// Run `bar` once per second
bar::spawn_after(1.secs()).unwrap();
}
// Hardware task, bound to a hardware interrupt
// The resources `s1` and `s2` are shared between all other tasks.
#[task(binds = UART0, priority = 3, shared = [s1, s2])]
fn uart0_interrupt(_: uart0_interrupt::Context) {
// This task is bound to the interrupt `UART0` and will run
// whenever the interrupt fires
// Note that RTIC does NOT clear the interrupt flag, this is up to the
// user
hprintln!("UART0 interrupt!");
}
}
<span class="boring">}</span></code></pre></pre>
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