rtic/examples/periodic.rs
Russell Sim 7266ffe3a6
Update example to use better initial value
The example above this in the documentation states

```
        // semantically, the monotonic timer is frozen at time "zero" during `init`
        // NOTE do *not* call `Instant::now` in this context; it will return a nonsense value
        let now = cx.start; // the start time of the system
```

It results in weird scheduling issues, but still eventually works.  `cx.start` is much more reliable.

Relates to https://github.com/rtfm-rs/cortex-m-rtfm/issues/196
2020-05-26 07:33:18 +02:00

35 lines
820 B
Rust

//! examples/periodic.rs
#![deny(unsafe_code)]
#![deny(warnings)]
#![no_main]
#![no_std]
use cortex_m_semihosting::hprintln;
use panic_semihosting as _;
use rtfm::cyccnt::{Instant, U32Ext};
const PERIOD: u32 = 8_000_000;
// NOTE: does NOT work on QEMU!
#[rtfm::app(device = lm3s6965, monotonic = rtfm::cyccnt::CYCCNT)]
const APP: () = {
#[init(schedule = [foo])]
fn init(cx: init::Context) {
// omitted: initialization of `CYCCNT`
cx.schedule.foo(cx.start + PERIOD.cycles()).unwrap();
}
#[task(schedule = [foo])]
fn foo(cx: foo::Context) {
let now = Instant::now();
hprintln!("foo(scheduled = {:?}, now = {:?})", cx.scheduled, now).unwrap();
cx.schedule.foo(cx.scheduled + PERIOD.cycles()).unwrap();
}
extern "C" {
fn UART0();
}
};