thermostat/src/timer.rs

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2019-03-15 01:13:25 +08:00
use core::cell::RefCell;
use cortex_m::interrupt::Mutex;
use cortex_m_rt::exception;
use stm32f4xx_hal::{
rcc::Clocks,
time::{U32Ext, MilliSeconds},
timer::{Timer, Event as TimerEvent},
stm32::SYST,
};
/// rate in Hz
const TIMER_RATE: u32 = 10;
2019-03-15 01:13:25 +08:00
/// interval duration in milliseconds
const TIMER_DELTA: u32 = 1000 / TIMER_RATE;
/// Elapsed time in milliseconds
static TIMER_MS: Mutex<RefCell<u32>> = Mutex::new(RefCell::new(0));
pub fn setup(syst: SYST, clocks: Clocks) {
let mut timer = Timer::syst(syst, TIMER_RATE.hz(), clocks);
timer.listen(TimerEvent::TimeOut);
}
#[exception]
fn SysTick() {
cortex_m::interrupt::free(|cs| {
*TIMER_MS.borrow(cs)
.borrow_mut() += TIMER_DELTA;
});
}
pub fn now() -> MilliSeconds {
let ms = cortex_m::interrupt::free(|cs| {
*TIMER_MS.borrow(cs)
.borrow()
});
ms.ms()
}