forked from M-Labs/thermostat
50 lines
1.1 KiB
Rust
50 lines
1.1 KiB
Rust
use core::cell::RefCell;
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use core::ops::Deref;
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use cortex_m::interrupt::Mutex;
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use cortex_m_rt::exception;
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use stm32f4xx_hal::{
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rcc::Clocks,
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time::U32Ext,
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timer::{Timer, Event as TimerEvent},
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stm32::SYST,
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};
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/// Rate in Hz
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const TIMER_RATE: u32 = 500;
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/// Interval duration in milliseconds
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const TIMER_DELTA: u32 = 1000 / TIMER_RATE;
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/// Elapsed time in milliseconds
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static TIMER_MS: Mutex<RefCell<u32>> = Mutex::new(RefCell::new(0));
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/// Setup SysTick exception
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pub fn setup(syst: SYST, clocks: Clocks) {
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let timer = Timer::syst(syst, &clocks);
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let mut countdown = timer.start_count_down(TIMER_RATE.hz());
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countdown.listen(TimerEvent::TimeOut);
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}
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/// SysTick exception (Timer)
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#[exception]
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fn SysTick() {
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cortex_m::interrupt::free(|cs| {
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*TIMER_MS.borrow(cs)
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.borrow_mut() += TIMER_DELTA;
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});
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}
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/// Obtain current time in milliseconds
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pub fn now() -> u32 {
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cortex_m::interrupt::free(|cs| {
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*TIMER_MS.borrow(cs)
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.borrow()
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.deref()
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})
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}
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/// block for at least `amount` milliseconds
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pub fn sleep(amount: u32) {
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let start = now();
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while now() - start <= amount {}
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}
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