44 lines
1.1 KiB
Rust
44 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::peripheral::syst::SystClkSource;
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use cortex_m_rt::exception;
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use stm32f4xx_hal::{pac::SYST, rcc::Clocks};
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/// Rate in Hz
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const TIMER_RATE: u32 = 1000;
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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(mut syst: SYST, clocks: Clocks) {
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syst.set_clock_source(SystClkSource::Core);
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syst.set_reload(clocks.hclk().to_Hz() / TIMER_RATE - 1);
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syst.enable_counter();
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syst.enable_interrupt();
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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).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| *TIMER_MS.borrow(cs).borrow().deref())
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}
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/// block for `amount` milliseconds
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pub fn sleep(amount: u32) {
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if amount == 0 {
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return;
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}
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let start = now();
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while now() - start <= amount - 1 {}
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}
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