embedded-trainings-2020/embedded-workshop-book/src/rtic-hello.md
2022-01-12 13:21:00 +01:00

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# RTIC hello
RTIC, Real-Time Interrupt-driven Concurrency, is a framework for building evented, time sensitive applications.
✅ Open the `src/bin/rtic-hello.rs` file.
RTIC applications are written in RTIC's Domain Specific Language (DSL). The DSL extends Rust syntax with custom attributes like `#[init]` and `#[idle]`.
RTIC makes a clearer distinction between the application's initialization phase, the `#[init]` function, and the application's main loop or main logic, the `#[idle]` function. The initialization phase runs with interrupts disabled and interrupts are re-enabled before the `idle` function is executed.
`rtic::app` is a procedural macro that generates extra Rust code, in addition to the user's functions. The fully expanded version of the macro can be found in the file `target/rtic-expansion.rs`. This file will contain the expansion of the procedural macro for the last compiled RTIC application.
✅ Build the `rtic-hello` example and look at the generated `rtic-expansion.rs` file.
You can use `rustfmt` on `target/rtic-expansion.rs` to make the generated code easier to read. Among other things, the file should contain the following lines. Note that interrupts are disabled during the execution of the `init` function:
```rust
unsafe extern "C" fn main() -> ! {
rtic::export::interrupt::disable();
let mut core: rtic::export::Peripherals = rtic::export::Peripherals::steal().into();
#[inline(never)]
fn __rtic_init_resources<F>(f: F)
where
F: FnOnce(),
{
f();
}
__rtic_init_resources(|| {
let (shared_resources, local_resources, mut monotonics) =
init(init::Context::new(core.into()));
rtic::export::interrupt::enable();
});
idle(idle::Context::new(&rtic::export::Priority::new(0)))
}
```