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//! Delay driver
//!
//! Implement the `DelayMs` and `DelayUs` traits from [embedded-hal].
//!
//! [embedded-hal]: https://docs.rs/embedded-hal/latest/embedded_hal/
pub use self::delay::Delay;
impl<T> embedded_hal::blocking::delay::DelayMs<T> for Delay
where
T: Into<u32>,
{
fn delay_ms(&mut self, ms: T) {
for _ in 0..ms.into() {
self.delay(1000u32);
}
}
}
impl<T> embedded_hal::blocking::delay::DelayUs<T> for Delay
where
T: Into<u32>,
{
fn delay_us(&mut self, us: T) {
self.delay(us.into());
}
}
#[cfg(feature = "eh1")]
impl embedded_hal_1::delay::DelayUs for Delay {
type Error = core::convert::Infallible;
fn delay_us(&mut self, us: u32) -> Result<(), Self::Error> {
self.delay(us);
Ok(())
}
}
#[cfg(riscv)]
mod delay {
use fugit::HertzU64;
use crate::{clock::Clocks, systimer::SystemTimer};
/// Uses the `SYSTIMER` peripheral for counting clock cycles, as
/// unfortunately the ESP32-C3 does NOT implement the `mcycle` CSR, which is
/// how we would normally do this.
pub struct Delay {
freq: HertzU64,
}
impl Delay {
/// Create a new Delay instance
pub fn new(clocks: &Clocks) -> Self {
// The counters and comparators are driven using `XTAL_CLK`. The average clock
// frequency is fXTAL_CLK/2.5, which is 16 MHz. The timer counting is
// incremented by 1/16 μs on each `CNT_CLK` cycle.
Self {
freq: HertzU64::MHz((clocks.xtal_clock.to_MHz() * 10 / 25) as u64),
}
}
/// Delay for the specified number of microseconds
pub fn delay(&self, us: u32) {
let t0 = SystemTimer::now();
let clocks = (us as u64 * self.freq.raw()) / HertzU64::MHz(1).raw();
while SystemTimer::now().wrapping_sub(t0) & SystemTimer::BIT_MASK <= clocks {}
}
}
}
#[cfg(xtensa)]
mod delay {
use fugit::HertzU64;
use crate::clock::Clocks;
/// Delay driver
///
/// Uses the built-in Xtensa timer from the `xtensa_lx` crate.
pub struct Delay {
freq: HertzU64,
}
impl Delay {
/// Instantiate the `Delay` driver
pub fn new(clocks: &Clocks) -> Self {
Self {
freq: HertzU64::MHz(clocks.cpu_clock.to_MHz() as u64),
}
}
/// Delay for the specified number of microseconds
pub fn delay(&self, us: u32) {
let clocks = (us as u64 * self.freq.raw()) / HertzU64::MHz(1).raw();
xtensa_lx::timer::delay(clocks as u32);
}
}
}