use void::Void; use libregister::{RegisterR, RegisterW}; use crate::{ clocks::Clocks, mpcore, time::Milliseconds, }; /// "uptime" #[derive(Clone, Copy)] pub struct GlobalTimer { regs: &'static mpcore::RegisterBlock, } impl GlobalTimer { /// Get the potentially uninitialized timer pub unsafe fn get() -> GlobalTimer { let mut regs = mpcore::RegisterBlock::new(); GlobalTimer { regs } } /// Get the timer with a reset pub fn start() -> GlobalTimer { let mut regs = mpcore::RegisterBlock::new(); Self::reset(&mut regs); GlobalTimer { regs } } fn reset(regs: &mut mpcore::RegisterBlock) { // Disable regs.global_timer_control.write( mpcore::GlobalTimerControl::zeroed() ); // Reset counters regs.global_timer_counter0.write( mpcore::ValueRegister::zeroed() ); regs.global_timer_counter1.write( mpcore::ValueRegister::zeroed() ); // find a prescaler value that matches CPU speed / 2 to us let clocks = Clocks::get(); let mut prescaler = clocks.cpu_3x2x() / 1_000_000; while prescaler > 256 { prescaler /= 2; } // Start regs.global_timer_control.write( mpcore::GlobalTimerControl::zeroed() .prescaler((prescaler - 1) as u8) .auto_increment_mode(true) .timer_enable(true) ); } /// read the raw counter value pub fn get_counter(&self) -> u64 { loop { let c1_pre = self.regs.global_timer_counter1.read().value(); let c0 = self.regs.global_timer_counter0.read().value(); let c1_post = self.regs.global_timer_counter1.read().value(); if c1_pre == c1_post { return ((c1_pre as u64) << 32) | (c0 as u64); } // retry if c0 has wrapped while reading. } } /// read and convert to time pub fn get_time(&self) -> Milliseconds { let prescaler = self.regs.global_timer_control.read().prescaler() as u64; let clocks = Clocks::get(); Milliseconds(self.get_counter() * (prescaler + 1) / (clocks.cpu_3x2x() as u64 / 1000)) } /// return a handle that has implements /// `embedded_hal::timer::CountDown` pub fn countdown(&self) -> CountDown { CountDown { timer: self.clone(), timeout: Milliseconds(0), } } } #[derive(Clone)] pub struct CountDown { timer: GlobalTimer, timeout: Milliseconds, } impl embedded_hal::timer::CountDown for CountDown { type Time = Milliseconds; fn start>(&mut self, count: T) { self.timeout = self.timer.get_time() + count.into(); } fn wait(&mut self) -> nb::Result<(), Void> { if self.timer.get_time() < self.timeout { Err(nb::Error::WouldBlock) } else { Ok(()) } } }