wip timers for embassy rtc
This commit is contained in:
Thales Fragoso
parent
212d905816
commit
e49e3723a8
@ -17,6 +17,8 @@ pub mod pwr;
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pub mod rcc;
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#[cfg(feature = "_rng")]
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pub mod rng;
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#[cfg(feature = "_timer")]
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pub mod rtc;
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#[cfg(feature = "_sdmmc")]
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pub mod sdmmc;
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#[cfg(feature = "_spi")]
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585
embassy-stm32/src/rtc.rs
Normal file
585
embassy-stm32/src/rtc.rs
Normal file
@ -0,0 +1,585 @@
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use core::cell::Cell;
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use core::convert::TryInto;
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use core::sync::atomic::{compiler_fence, AtomicU32, Ordering};
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use embassy::interrupt::InterruptExt;
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use embassy::time::{Clock, TICKS_PER_SECOND};
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use embassy::util::AtomicWaker;
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use crate::interrupt::{CriticalSection, Interrupt, Mutex};
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use crate::pac::timer::TimGp16;
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use crate::time::Hertz;
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// RTC timekeeping works with something we call "periods", which are time intervals
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// of 2^15 ticks. The RTC counter value is 16 bits, so one "overflow cycle" is 2 periods.
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//
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// A `period` count is maintained in parallel to the RTC hardware `counter`, like this:
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// - `period` and `counter` start at 0
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// - `period` is incremented on overflow (at counter value 0)
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// - `period` is incremented "midway" between overflows (at counter value 0x8000)
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//
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// Therefore, when `period` is even, counter is in 0..0x7FFF. When odd, counter is in 0x8000..0xFFFF
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// This allows for now() to return the correct value even if it races an overflow.
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//
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// To get `now()`, `period` is read first, then `counter` is read. If the counter value matches
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// the expected range for the `period` parity, we're done. If it doesn't, this means that
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// a new period start has raced us between reading `period` and `counter`, so we assume the `counter` value
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// corresponds to the next period.
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//
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// `period` is a 32bit integer, so It overflows on 2^32 * 2^15 / 32768 seconds of uptime, which is 136 years.
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fn calc_now(period: u32, counter: u16) -> u64 {
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((period as u64) << 15) + ((counter as u32 ^ ((period & 1) << 15)) as u64)
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}
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struct AlarmState {
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timestamp: Cell<u64>,
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#[allow(clippy::type_complexity)]
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callback: Cell<Option<(fn(*mut ()), *mut ())>>,
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}
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impl AlarmState {
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fn new() -> Self {
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Self {
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timestamp: Cell::new(u64::MAX),
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callback: Cell::new(None),
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}
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}
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}
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// TODO: This is sometimes wasteful, try to find a better way
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const ALARM_COUNT: usize = 3;
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/// RTC timer that can be used by the executor and to set alarms.
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///
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/// It can work with Timers 2, 3, 4, 5, 9 and 12. Timers 9 and 12 only have one alarm available,
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/// while the others have three each.
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/// This timer works internally with a unit of 2^15 ticks, which means that if a call to
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/// [`embassy::time::Clock::now`] is blocked for that amount of ticks the returned value will be
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/// wrong (an old value). The current default tick rate is 32768 ticks per second.
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pub struct RTC<T: Instance> {
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_inner: T,
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irq: T::Interrupt,
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/// Number of 2^23 periods elapsed since boot.
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period: AtomicU32,
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/// Timestamp at which to fire alarm. u64::MAX if no alarm is scheduled.
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alarms: Mutex<[AlarmState; ALARM_COUNT]>,
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}
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impl<T: Instance> RTC<T> {
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pub fn new(peripheral: T, irq: T::Interrupt) -> Self {
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Self {
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_inner: peripheral,
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irq,
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period: AtomicU32::new(0),
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alarms: Mutex::new([AlarmState::new(), AlarmState::new(), AlarmState::new()]),
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}
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}
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pub fn start(&'static self, pfreq: Hertz, ppre: u8) {
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let inner = T::inner();
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// NOTE(unsafe) Critical section to use the unsafe methods
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critical_section::with(|_| {
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unsafe {
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inner.prepare(pfreq, ppre);
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}
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self.irq.set_handler_context(self as *const _ as *mut _);
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self.irq.set_handler(|ptr| unsafe {
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let this = &*(ptr as *const () as *const Self);
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this.on_interrupt();
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});
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self.irq.unpend();
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self.irq.enable();
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unsafe {
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inner.start_counter();
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}
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})
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}
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fn on_interrupt(&self) {
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let inner = T::inner();
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// NOTE(unsafe) Use critical section to access the methods
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// XXX: reduce the size of this critical section ?
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critical_section::with(|cs| unsafe {
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if inner.overflow_interrupt_status() {
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inner.overflow_clear_flag();
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self.next_period();
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}
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// Half overflow
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if inner.compare_interrupt_status(0) {
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inner.compare_clear_flag(0);
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self.next_period();
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}
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for n in 1..=ALARM_COUNT {
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if inner.compare_interrupt_status(n) {
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inner.compare_clear_flag(n);
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self.trigger_alarm(n, cs);
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}
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}
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})
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}
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fn next_period(&self) {
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let inner = T::inner();
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let period = self.period.fetch_add(1, Ordering::Relaxed) + 1;
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let t = (period as u64) << 15;
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critical_section::with(move |cs| {
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for n in 1..=ALARM_COUNT {
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let alarm = &self.alarms.borrow(cs)[n - 1];
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let at = alarm.timestamp.get();
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let diff = at - t;
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if diff < 0xc000 {
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inner.set_compare(n, at as u16);
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// NOTE(unsafe) We're in a critical section
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unsafe {
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inner.set_compare_interrupt(n, true);
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}
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}
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}
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})
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}
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fn trigger_alarm(&self, n: usize, cs: CriticalSection) {
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let inner = T::inner();
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// NOTE(unsafe) We have a critical section
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unsafe {
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inner.set_compare_interrupt(n, false);
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}
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let alarm = &self.alarms.borrow(cs)[n - 1];
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alarm.timestamp.set(u64::MAX);
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// Call after clearing alarm, so the callback can set another alarm.
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if let Some((f, ctx)) = alarm.callback.get() {
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f(ctx);
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}
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}
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fn set_alarm_callback(&self, n: usize, callback: fn(*mut ()), ctx: *mut ()) {
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critical_section::with(|cs| {
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let alarm = &self.alarms.borrow(cs)[n - 1];
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alarm.callback.set(Some((callback, ctx)));
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})
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}
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fn set_alarm(&self, n: usize, timestamp: u64) {
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critical_section::with(|cs| {
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let inner = T::inner();
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let alarm = &self.alarms.borrow(cs)[n - 1];
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alarm.timestamp.set(timestamp);
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let t = self.now();
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if timestamp <= t {
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self.trigger_alarm(n, cs);
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return;
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}
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let diff = timestamp - t;
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if diff < 0xc000 {
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let safe_timestamp = timestamp.max(t + 3);
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inner.set_compare(n, safe_timestamp as u16);
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// NOTE(unsafe) We're in a critical section
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unsafe {
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inner.set_compare_interrupt(n, true);
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}
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} else {
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unsafe {
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inner.set_compare_interrupt(n, false);
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}
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}
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})
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}
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pub fn alarm1(&'static self) -> Alarm<T> {
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Alarm { n: 1, rtc: self }
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}
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pub fn alarm2(&'static self) -> Alarm<T> {
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Alarm { n: 2, rtc: self }
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}
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pub fn alarm3(&'static self) -> Alarm<T> {
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Alarm { n: 3, rtc: self }
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}
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}
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impl<T: Instance> embassy::time::Clock for RTC<T> {
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fn now(&self) -> u64 {
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let inner = T::inner();
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let period = self.period.load(Ordering::Relaxed);
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compiler_fence(Ordering::Acquire);
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let counter = inner.counter();
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calc_now(period, counter)
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}
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}
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pub struct Alarm<T: Instance> {
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n: usize,
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rtc: &'static RTC<T>,
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}
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impl<T: Instance> embassy::time::Alarm for Alarm<T> {
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fn set_callback(&self, callback: fn(*mut ()), ctx: *mut ()) {
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self.rtc.set_alarm_callback(self.n, callback, ctx);
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}
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fn set(&self, timestamp: u64) {
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self.rtc.set_alarm(self.n, timestamp);
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}
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fn clear(&self) {
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self.rtc.set_alarm(self.n, u64::MAX);
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}
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}
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pub struct TimerInner(pub(crate) TimGp16);
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impl TimerInner {
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unsafe fn prepare(&self, pfreq: Hertz, ppre: u8) {
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self.stop_and_reset();
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let multiplier = if ppre == 1 { 1 } else { 2 };
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let freq = pfreq.0 * multiplier;
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let psc = freq / TICKS_PER_SECOND as u32 - 1;
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let psc: u16 = psc.try_into().unwrap();
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self.set_psc_arr(psc, u16::MAX);
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// Mid-way point
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self.set_compare(0, 0x8000);
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self.set_compare_interrupt(0, true);
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}
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unsafe fn start_counter(&self) {
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self.0.cr1().modify(|w| w.set_cen(true));
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}
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unsafe fn stop_and_reset(&self) {
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let regs = self.0;
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regs.cr1().modify(|w| w.set_cen(false));
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regs.cnt().write(|w| w.set_cnt(0));
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}
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fn overflow_interrupt_status(&self) -> bool {
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// NOTE(unsafe) Atomic read with no side-effects
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unsafe { self.0.sr().read().uif() }
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}
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unsafe fn overflow_clear_flag(&self) {
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self.0.sr().modify(|w| w.set_uif(false));
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}
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unsafe fn set_psc_arr(&self, psc: u16, arr: u16) {
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use crate::pac::timer::vals::Urs;
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let regs = self.0;
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regs.psc().write(|w| w.set_psc(psc));
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regs.arr().write(|w| w.set_arr(arr));
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// Set URS, generate update and clear URS
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regs.cr1().modify(|w| w.set_urs(Urs::COUNTERONLY));
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regs.egr().write(|w| w.set_ug(true));
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regs.cr1().modify(|w| w.set_urs(Urs::ANYEVENT));
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}
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fn compare_interrupt_status(&self, n: usize) -> bool {
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if n > 3 {
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false
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} else {
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// NOTE(unsafe) Atomic read with no side-effects
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unsafe { self.0.sr().read().ccif(n) }
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}
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}
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unsafe fn compare_clear_flag(&self, n: usize) {
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if n > 3 {
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return;
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}
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self.0.sr().modify(|w| w.set_ccif(n, false));
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}
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fn set_compare(&self, n: usize, value: u16) {
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if n > 3 {
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return;
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}
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// NOTE(unsafe) Atomic write
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unsafe {
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self.0.ccr(n).write(|w| w.set_ccr(value));
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}
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}
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unsafe fn set_compare_interrupt(&self, n: usize, enable: bool) {
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if n > 3 {
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return;
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}
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self.0.dier().modify(|w| w.set_ccie(n, enable));
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}
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fn counter(&self) -> u16 {
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// NOTE(unsafe) Atomic read with no side-effects
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unsafe { self.0.cnt().read().cnt() }
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}
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}
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// ------------------------------------------------------
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pub(crate) mod sealed {
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use super::*;
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pub trait Instance {
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type Interrupt: Interrupt;
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fn inner() -> TimerInner;
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fn state() -> &'static AtomicWaker;
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}
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}
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pub trait Instance: sealed::Instance + Sized + 'static {}
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/*
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#[allow(unused_macros)]
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macro_rules! impl_timer {
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($module:ident: ($TYPE:ident, $INT:ident, $apbenr:ident, $enrbit:expr, $apbrstr:ident, $rstrbit:expr, $ppre:ident, $pclk: ident), 3) => {
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mod $module {
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use super::*;
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impl sealed::Instance for $TYPE {}
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impl Instance for $TYPE {
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type Interrupt = interrupt::$INT;
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fn set_compare(&self, n: usize, value: u16) {
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// NOTE(unsafe) these registers accept all the range of u16 values
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match n {
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0 => self.ccr1.write(|w| unsafe { w.bits(value.into()) }),
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1 => self.ccr2.write(|w| unsafe { w.bits(value.into()) }),
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2 => self.ccr3.write(|w| unsafe { w.bits(value.into()) }),
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3 => self.ccr4.write(|w| unsafe { w.bits(value.into()) }),
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_ => {}
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}
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}
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fn set_compare_interrupt(&self, n: usize, enable: bool) {
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if n > 3 {
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return;
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}
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let bit = n as u8 + 1;
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unsafe {
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if enable {
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bb::set(&self.dier, bit);
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} else {
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bb::clear(&self.dier, bit);
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}
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}
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}
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fn compare_interrupt_status(&self, n: usize) -> bool {
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let status = self.sr.read();
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match n {
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0 => status.cc1if().bit_is_set(),
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1 => status.cc2if().bit_is_set(),
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2 => status.cc3if().bit_is_set(),
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3 => status.cc4if().bit_is_set(),
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_ => false,
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}
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}
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fn compare_clear_flag(&self, n: usize) {
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if n > 3 {
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return;
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}
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let bit = n as u8 + 1;
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unsafe {
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bb::clear(&self.sr, bit);
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}
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}
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fn overflow_interrupt_status(&self) -> bool {
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self.sr.read().uif().bit_is_set()
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}
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fn overflow_clear_flag(&self) {
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unsafe {
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bb::clear(&self.sr, 0);
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}
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}
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fn set_psc_arr(&self, psc: u16, arr: u16) {
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// NOTE(unsafe) All u16 values are valid
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self.psc.write(|w| unsafe { w.bits(psc.into()) });
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self.arr.write(|w| unsafe { w.bits(arr.into()) });
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unsafe {
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// Set URS, generate update, clear URS
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bb::set(&self.cr1, 2);
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self.egr.write(|w| w.ug().set_bit());
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bb::clear(&self.cr1, 2);
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}
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}
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fn stop_and_reset(&self) {
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unsafe {
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bb::clear(&self.cr1, 0);
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}
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self.cnt.reset();
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}
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fn start(&self) {
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unsafe { bb::set(&self.cr1, 0) }
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}
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fn counter(&self) -> u16 {
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self.cnt.read().bits() as u16
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}
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fn ppre(clocks: &Clocks) -> u8 {
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clocks.$ppre()
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}
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fn pclk(clocks: &Clocks) -> u32 {
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clocks.$pclk().0
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}
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}
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}
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};
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($module:ident: ($TYPE:ident, $INT:ident, $apbenr:ident, $enrbit:expr, $apbrstr:ident, $rstrbit:expr, $ppre:ident, $pclk: ident), 1) => {
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mod $module {
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use super::*;
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use crate::hal::pac::{$TYPE, RCC};
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impl sealed::Sealed for $TYPE {}
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impl Instance for $TYPE {
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type Interrupt = interrupt::$INT;
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const REAL_ALARM_COUNT: usize = 1;
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fn enable_clock(&self) {
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// NOTE(unsafe) It will only be used for atomic operations
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unsafe {
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let rcc = &*RCC::ptr();
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bb::set(&rcc.$apbenr, $enrbit);
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bb::set(&rcc.$apbrstr, $rstrbit);
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bb::clear(&rcc.$apbrstr, $rstrbit);
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}
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}
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fn set_compare(&self, n: usize, value: u16) {
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// NOTE(unsafe) these registers accept all the range of u16 values
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match n {
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0 => self.ccr1.write(|w| unsafe { w.bits(value.into()) }),
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||||
1 => self.ccr2.write(|w| unsafe { w.bits(value.into()) }),
|
||||
_ => {}
|
||||
}
|
||||
}
|
||||
|
||||
fn set_compare_interrupt(&self, n: usize, enable: bool) {
|
||||
if n > 1 {
|
||||
return;
|
||||
}
|
||||
let bit = n as u8 + 1;
|
||||
unsafe {
|
||||
if enable {
|
||||
bb::set(&self.dier, bit);
|
||||
} else {
|
||||
bb::clear(&self.dier, bit);
|
||||
}
|
||||
}
|
||||
}
|
||||
|
||||
fn compare_interrupt_status(&self, n: usize) -> bool {
|
||||
let status = self.sr.read();
|
||||
match n {
|
||||
0 => status.cc1if().bit_is_set(),
|
||||
1 => status.cc2if().bit_is_set(),
|
||||
_ => false,
|
||||
}
|
||||
}
|
||||
|
||||
fn compare_clear_flag(&self, n: usize) {
|
||||
if n > 1 {
|
||||
return;
|
||||
}
|
||||
let bit = n as u8 + 1;
|
||||
unsafe {
|
||||
bb::clear(&self.sr, bit);
|
||||
}
|
||||
}
|
||||
|
||||
fn overflow_interrupt_status(&self) -> bool {
|
||||
self.sr.read().uif().bit_is_set()
|
||||
}
|
||||
|
||||
fn overflow_clear_flag(&self) {
|
||||
unsafe {
|
||||
bb::clear(&self.sr, 0);
|
||||
}
|
||||
}
|
||||
|
||||
fn set_psc_arr(&self, psc: u16, arr: u16) {
|
||||
// NOTE(unsafe) All u16 values are valid
|
||||
self.psc.write(|w| unsafe { w.bits(psc.into()) });
|
||||
self.arr.write(|w| unsafe { w.bits(arr.into()) });
|
||||
|
||||
unsafe {
|
||||
// Set URS, generate update, clear URS
|
||||
bb::set(&self.cr1, 2);
|
||||
self.egr.write(|w| w.ug().set_bit());
|
||||
bb::clear(&self.cr1, 2);
|
||||
}
|
||||
}
|
||||
|
||||
fn stop_and_reset(&self) {
|
||||
unsafe {
|
||||
bb::clear(&self.cr1, 0);
|
||||
}
|
||||
self.cnt.reset();
|
||||
}
|
||||
|
||||
fn start(&self) {
|
||||
unsafe { bb::set(&self.cr1, 0) }
|
||||
}
|
||||
|
||||
fn counter(&self) -> u16 {
|
||||
self.cnt.read().bits() as u16
|
||||
}
|
||||
|
||||
fn ppre(clocks: &Clocks) -> u8 {
|
||||
clocks.$ppre()
|
||||
}
|
||||
|
||||
fn pclk(clocks: &Clocks) -> u32 {
|
||||
clocks.$pclk().0
|
||||
}
|
||||
}
|
||||
}
|
||||
};
|
||||
}
|
||||
*/
|
||||
|
||||
/*
|
||||
impl_timer!(tim2: (TIM2, TIM2, apb1enr, 0, apb1rstr, 0, ppre1, pclk1), 3);
|
||||
|
||||
impl_timer!(tim3: (TIM3, TIM3, apb1enr, 1, apb1rstr, 1, ppre1, pclk1), 3);
|
||||
|
||||
|
||||
impl_timer!(tim4: (TIM4, TIM4, apb1enr, 2, apb1rstr, 2, ppre1, pclk1), 3);
|
||||
|
||||
impl_timer!(tim5: (TIM5, TIM5, apb1enr, 3, apb1rstr, 3, ppre1, pclk1), 3);
|
||||
|
||||
impl_timer!(tim9: (TIM9, TIM1_BRK_TIM9, apb2enr, 16, apb2rstr, 16, ppre2, pclk2), 1);
|
||||
|
||||
#[cfg(not(any(feature = "stm32f401", feature = "stm32f410", feature = "stm32f411")))]
|
||||
impl_timer!(tim12: (TIM12, TIM8_BRK_TIM12, apb1enr, 6, apb1rstr, 6, ppre1, pclk1), 1);
|
||||
*/
|
||||
Loading…
Reference in New Issue
Block a user