embassy/embassy-nrf/src/pwm.rs

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6.5 KiB
Rust
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#![macro_use]
use core::cell::UnsafeCell;
use core::marker::PhantomData;
use core::sync::atomic::{compiler_fence, Ordering};
use embassy::util::Unborrow;
use embassy_hal_common::unborrow;
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use crate::gpio::sealed::Pin as _;
use crate::gpio::OptionalPin as GpioOptionalPin;
use crate::interrupt::Interrupt;
use crate::pac;
#[derive(Debug, Eq, PartialEq, Clone, Copy)]
pub enum Prescaler {
Div1,
Div2,
Div4,
Div8,
Div16,
Div32,
Div64,
Div128,
}
/// Interface to the UARTE peripheral
pub struct Pwm<'d, T: Instance> {
phantom: PhantomData<&'d mut T>,
}
impl<'d, T: Instance> Pwm<'d, T> {
/// Creates the interface to a UARTE instance.
/// Sets the baud rate, parity and assigns the pins to the UARTE peripheral.
///
/// # Safety
///
/// The returned API is safe unless you use `mem::forget` (or similar safe mechanisms)
/// on stack allocated buffers which which have been passed to [`send()`](Pwm::send)
/// or [`receive`](Pwm::receive).
#[allow(unused_unsafe)]
pub fn new(
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_pwm: impl Unborrow<Target = T> + 'd,
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ch0: impl Unborrow<Target = impl GpioOptionalPin> + 'd,
ch1: impl Unborrow<Target = impl GpioOptionalPin> + 'd,
ch2: impl Unborrow<Target = impl GpioOptionalPin> + 'd,
ch3: impl Unborrow<Target = impl GpioOptionalPin> + 'd,
) -> Self {
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unborrow!(ch0, ch1, ch2, ch3);
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let r = T::regs();
let s = T::state();
if let Some(pin) = ch0.pin_mut() {
pin.set_low();
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pin.conf().write(|w| w.dir().output());
}
if let Some(pin) = ch1.pin_mut() {
pin.set_low();
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pin.conf().write(|w| w.dir().output());
}
if let Some(pin) = ch2.pin_mut() {
pin.set_low();
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pin.conf().write(|w| w.dir().output());
}
if let Some(pin) = ch3.pin_mut() {
pin.set_low();
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pin.conf().write(|w| w.dir().output());
}
r.psel.out[0].write(|w| unsafe { w.bits(ch0.psel_bits()) });
r.psel.out[1].write(|w| unsafe { w.bits(ch1.psel_bits()) });
r.psel.out[2].write(|w| unsafe { w.bits(ch2.psel_bits()) });
r.psel.out[3].write(|w| unsafe { w.bits(ch3.psel_bits()) });
// Disable all interrupts
r.intenclr.write(|w| unsafe { w.bits(0xFFFF_FFFF) });
// Enable
r.enable.write(|w| w.enable().enabled());
r.seq0
.ptr
.write(|w| unsafe { w.bits(&s.duty as *const _ as u32) });
r.seq0.cnt.write(|w| unsafe { w.bits(4) });
r.seq0.refresh.write(|w| unsafe { w.bits(32) });
r.seq0.enddelay.write(|w| unsafe { w.bits(0) });
r.decoder.write(|w| {
w.load().individual();
w.mode().refresh_count()
});
r.mode.write(|w| w.updown().up());
r.prescaler.write(|w| w.prescaler().div_1());
r.countertop
.write(|w| unsafe { w.countertop().bits(32767) });
r.loop_.write(|w| w.cnt().disabled());
Self {
phantom: PhantomData,
}
}
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/// Enables the PWM generator.
#[inline(always)]
pub fn enable(&self) {
let r = T::regs();
r.enable.write(|w| w.enable().enabled());
}
/// Disables the PWM generator.
#[inline(always)]
pub fn disable(&self) {
let r = T::regs();
r.enable.write(|w| w.enable().disabled());
}
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/// Sets duty cycle (15 bit) for a PWM channel.
pub fn set_duty(&self, channel: usize, duty: u16) {
let s = T::state();
unsafe { (*s.duty.get())[channel] = duty & 0x7FFF };
compiler_fence(Ordering::SeqCst);
T::regs().tasks_seqstart[0].write(|w| unsafe { w.bits(1) });
}
/// Sets the PWM clock prescaler.
#[inline(always)]
pub fn set_prescaler(&self, div: Prescaler) {
T::regs().prescaler.write(|w| w.prescaler().bits(div as u8));
}
/// Sets the PWM clock prescaler.
#[inline(always)]
pub fn prescaler(&self) -> Prescaler {
match T::regs().prescaler.read().prescaler().bits() {
0 => Prescaler::Div1,
1 => Prescaler::Div2,
2 => Prescaler::Div4,
3 => Prescaler::Div8,
4 => Prescaler::Div16,
5 => Prescaler::Div32,
6 => Prescaler::Div64,
7 => Prescaler::Div128,
_ => unreachable!(),
}
}
/// Sets the maximum duty cycle value.
#[inline(always)]
pub fn set_max_duty(&self, duty: u16) {
T::regs()
.countertop
.write(|w| unsafe { w.countertop().bits(duty.min(32767u16)) });
}
/// Returns the maximum duty cycle value.
#[inline(always)]
pub fn max_duty(&self) -> u16 {
T::regs().countertop.read().countertop().bits()
}
/// Sets the PWM output frequency.
#[inline(always)]
pub fn set_period(&self, freq: u32) {
let clk = 16_000_000u32 >> (self.prescaler() as u8);
let duty = clk / freq;
self.set_max_duty(duty.min(32767) as u16);
}
/// Returns the PWM output frequency.
#[inline(always)]
pub fn period(&self) -> u32 {
let clk = 16_000_000u32 >> (self.prescaler() as u8);
let max_duty = self.max_duty() as u32;
clk / max_duty
}
}
impl<'a, T: Instance> Drop for Pwm<'a, T> {
fn drop(&mut self) {
let r = T::regs();
r.enable.write(|w| w.enable().disabled());
info!("pwm drop: done");
// TODO: disable pins
}
}
pub(crate) mod sealed {
use super::*;
pub struct State {
pub duty: UnsafeCell<[u16; 4]>,
}
unsafe impl Sync for State {}
impl State {
pub const fn new() -> Self {
Self {
duty: UnsafeCell::new([0; 4]),
}
}
}
pub trait Instance {
fn regs() -> &'static pac::pwm0::RegisterBlock;
fn state() -> &'static State;
}
}
pub trait Instance: Unborrow<Target = Self> + sealed::Instance + 'static {
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type Interrupt: Interrupt;
}
macro_rules! impl_pwm {
($type:ident, $pac_type:ident, $irq:ident) => {
impl crate::pwm::sealed::Instance for peripherals::$type {
fn regs() -> &'static pac::pwm0::RegisterBlock {
unsafe { &*pac::$pac_type::ptr() }
}
fn state() -> &'static crate::pwm::sealed::State {
static STATE: crate::pwm::sealed::State = crate::pwm::sealed::State::new();
&STATE
}
}
impl crate::pwm::Instance for peripherals::$type {
type Interrupt = crate::interrupt::$irq;
}
};
}