esp_hal/pcnt/unit.rs
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//! # PCNT - Unit Module
//!
//! ## Overview
//! The `unit` module is responsible for configuring and handling individual
//! units of the `PCNT` peripheral. Each unit represents a separate instance of
//! the `PCNT` module, identified by unit numbers like `Unit0`, `Unit1`, and so
//! on. Users can interact with these units to configure settings such as low
//! and high limits, thresholds, and optional filtering. The unit module also
//! enables users to pause, resume, and clear the counter, as well as enable or
//! disable interrupts for specific events associated with the unit.
use core::marker::PhantomData;
use critical_section::CriticalSection;
use crate::{pcnt::channel::Channel, peripherals::PCNT, system::GenericPeripheralGuard};
/// Invalid filter threshold value
#[derive(Debug, Clone, Copy, PartialEq)]
#[cfg_attr(feature = "defmt", derive(defmt::Format))]
pub struct InvalidFilterThreshold;
/// Invalid low limit - must be < 0
#[derive(Debug, Clone, Copy, PartialEq)]
#[cfg_attr(feature = "defmt", derive(defmt::Format))]
pub struct InvalidLowLimit;
/// Invalid high limit - must be > 0
#[derive(Debug, Clone, Copy, PartialEq)]
#[cfg_attr(feature = "defmt", derive(defmt::Format))]
pub struct InvalidHighLimit;
/// the current status of the counter.
#[derive(Copy, Clone, Debug, Default, PartialEq)]
#[cfg_attr(feature = "defmt", derive(defmt::Format))]
pub enum ZeroMode {
/// pulse counter decreases from positive to 0.
#[default]
PosZero = 0,
/// pulse counter increases from negative to 0
NegZero = 1,
/// pulse counter is negative (not implemented?)
Negative = 2,
/// pulse counter is positive (not implemented?)
Positive = 3,
}
impl From<u8> for ZeroMode {
fn from(value: u8) -> Self {
match value {
0 => Self::PosZero,
1 => Self::NegZero,
2 => Self::Negative,
3 => Self::Positive,
_ => unreachable!(), // TODO: is this good enough? should we use some default?
}
}
}
/// Events that can occur in a pulse counter unit.
#[derive(Copy, Clone, Debug, Default)]
#[cfg_attr(feature = "defmt", derive(defmt::Format))]
pub struct Events {
/// Set when the pulse counter reaches the low limit.
pub low_limit: bool,
/// Set when the pulse counter reaches the high limit.
pub high_limit: bool,
/// Set when the pulse counter crosses threshold 0.
pub threshold0: bool,
/// Set when the pulse counter crosses threshold 1.
pub threshold1: bool,
/// Set when the pulse counter reaches zero.
pub zero: bool,
}
/// Represents a pulse counter unit.
#[non_exhaustive]
pub struct Unit<'d, const NUM: usize> {
/// The counter for PCNT unit.
pub counter: Counter<'d, NUM>,
/// The first channel in PCNT unit.
pub channel0: Channel<'d, NUM, 0>,
/// The second channel in PCNT unit.
pub channel1: Channel<'d, NUM, 1>,
_guard: GenericPeripheralGuard<{ crate::system::Peripheral::Pcnt as u8 }>,
}
impl<const NUM: usize> Unit<'_, NUM> {
/// return a new Unit
pub(super) fn new() -> Self {
let guard = GenericPeripheralGuard::new();
Self {
counter: Counter::new(),
channel0: Channel::new(),
channel1: Channel::new(),
_guard: guard,
}
}
/// Configures a lower limit to the count value.
///
/// When the count drops to this value:
/// - A low limit interrupt is triggered.
/// - The count is reset to 0.
///
/// If None is specified, then no interrupt is triggered and
/// the count wraps around after [i16::MIN].
///
/// Note: The specified value must be negative.
pub fn set_low_limit(&self, value: Option<i16>) -> Result<(), InvalidLowLimit> {
let pcnt = PCNT::regs();
let unit = pcnt.unit(NUM);
if let Some(value) = value {
// low limit must be >= or the limit is -32768 and when that's
// hit the event status claims it was the high limit.
// tested on an esp32s3
if !value.is_negative() {
return Err(InvalidLowLimit);
} else {
unit.conf2()
.modify(|_, w| unsafe { w.cnt_l_lim().bits(value as u16) });
unit.conf0().modify(|_, w| w.thr_l_lim_en().set_bit());
}
} else {
unit.conf0().modify(|_, w| w.thr_l_lim_en().clear_bit());
}
Ok(())
}
/// Configures a high limit to the count value.
///
/// When the count rises to this value:
/// - A high limit interrupt is triggered.
/// - The count is reset to 0.
///
/// If None is specified, then no interrupt is triggered and
/// the count wraps around after [i16::MAX].
///
/// Note: The specified value must be positive.
pub fn set_high_limit(&self, value: Option<i16>) -> Result<(), InvalidHighLimit> {
let pcnt = PCNT::regs();
let unit = pcnt.unit(NUM);
if let Some(value) = value {
if !value.is_positive() {
return Err(InvalidHighLimit);
} else {
unit.conf2()
.modify(|_, w| unsafe { w.cnt_h_lim().bits(value as u16) });
unit.conf0().modify(|_, w| w.thr_h_lim_en().set_bit());
}
} else {
unit.conf0().modify(|_, w| w.thr_h_lim_en().clear_bit());
}
Ok(())
}
/// Configures a threshold value to trigger an interrupt.
///
/// When the count equals this value a threshold0 interrupt is triggered.
/// If None is specified, then no interrupt is triggered.
pub fn set_threshold0(&self, value: Option<i16>) {
let pcnt = PCNT::regs();
let unit = pcnt.unit(NUM);
if let Some(value) = value {
unit.conf1()
.modify(|_, w| unsafe { w.cnt_thres0().bits(value as u16) });
unit.conf0().modify(|_, w| w.thr_thres0_en().set_bit());
} else {
unit.conf0().modify(|_, w| w.thr_thres0_en().clear_bit());
}
}
/// Configures a threshold value to trigger an interrupt.
///
/// When the count equals this value a threshold1 interrupt is triggered.
/// If None is specified, then no interrupt is triggered.
pub fn set_threshold1(&self, value: Option<i16>) {
let pcnt = PCNT::regs();
let unit = pcnt.unit(NUM);
if let Some(value) = value {
unit.conf1()
.modify(|_, w| unsafe { w.cnt_thres1().bits(value as u16) });
unit.conf0().modify(|_, w| w.thr_thres1_en().set_bit());
} else {
unit.conf0().modify(|_, w| w.thr_thres1_en().clear_bit());
}
}
/// Configures the glitch filter hardware of the unit.
///
/// `threshold` is the minimum number of APB_CLK cycles for a pulse to be
/// considered valid. If it is None, the filter is disabled.
///
/// Note: This maximum possible threshold is 1023.
pub fn set_filter(&self, threshold: Option<u16>) -> Result<(), InvalidFilterThreshold> {
let pcnt = PCNT::regs();
let unit = pcnt.unit(NUM);
match threshold {
None => {
unit.conf0().modify(|_, w| w.filter_en().clear_bit());
}
Some(threshold) => {
if threshold > 1023 {
return Err(InvalidFilterThreshold);
}
unit.conf0().modify(|_, w| unsafe {
w.filter_thres().bits(threshold).filter_en().set_bit()
});
}
}
Ok(())
}
/// Resets the counter value to zero.
pub fn clear(&self) {
let pcnt = PCNT::regs();
critical_section::with(|_cs| {
pcnt.ctrl().modify(|_, w| w.cnt_rst_u(NUM as u8).set_bit());
// TODO: does this need a delay? (liebman / Jan 2 2023)
pcnt.ctrl()
.modify(|_, w| w.cnt_rst_u(NUM as u8).clear_bit());
});
}
/// Pause the counter
pub fn pause(&self) {
let pcnt = PCNT::regs();
critical_section::with(|_cs| {
pcnt.ctrl()
.modify(|_, w| w.cnt_pause_u(NUM as u8).set_bit());
});
}
/// Resume the counter
pub fn resume(&self) {
let pcnt = PCNT::regs();
critical_section::with(|_cs| {
pcnt.ctrl()
.modify(|_, w| w.cnt_pause_u(NUM as u8).clear_bit());
});
}
/// Get the latest events for this unit.
pub fn events(&self) -> Events {
let pcnt = PCNT::regs();
let status = pcnt.u_status(NUM).read();
Events {
low_limit: status.l_lim().bit(),
high_limit: status.h_lim().bit(),
threshold0: status.thres0().bit(),
threshold1: status.thres1().bit(),
zero: status.zero().bit(),
}
}
/// Get the mode of the last zero crossing
pub fn zero_mode(&self) -> ZeroMode {
let pcnt = PCNT::regs();
pcnt.u_status(NUM).read().zero_mode().bits().into()
}
/// Enable interrupts for this unit.
pub fn listen(&self) {
let pcnt = PCNT::regs();
critical_section::with(|_cs| {
pcnt.int_ena()
.modify(|_, w| w.cnt_thr_event_u(NUM as u8).set_bit());
});
}
/// Disable interrupts for this unit.
pub fn unlisten(&self, _cs: CriticalSection<'_>) {
let pcnt = PCNT::regs();
critical_section::with(|_cs| {
pcnt.int_ena()
.modify(|_, w| w.cnt_thr_event_u(NUM as u8).clear_bit());
});
}
/// Returns true if an interrupt is active for this unit.
pub fn interrupt_is_set(&self) -> bool {
let pcnt = PCNT::regs();
pcnt.int_raw().read().cnt_thr_event_u(NUM as u8).bit()
}
/// Clear the interrupt bit for this unit.
pub fn reset_interrupt(&self) {
let pcnt = PCNT::regs();
critical_section::with(|_cs| {
pcnt.int_clr()
.write(|w| w.cnt_thr_event_u(NUM as u8).set_bit());
});
}
/// Get the current counter value.
pub fn value(&self) -> i16 {
self.counter.get()
}
}
impl<const NUM: usize> Drop for Unit<'_, NUM> {
fn drop(&mut self) {
// This is here to prevent the destructuring of Unit.
}
}
// The entire Unit is Send but the individual channels are not.
unsafe impl<const NUM: usize> Send for Unit<'_, NUM> {}
/// Represents the counter within a pulse counter unit.
#[derive(Clone)]
pub struct Counter<'d, const NUM: usize> {
_phantom: PhantomData<&'d ()>,
}
impl<const NUM: usize> Counter<'_, NUM> {
fn new() -> Self {
Self {
_phantom: PhantomData,
}
}
/// Get the current counter value.
pub fn get(&self) -> i16 {
let pcnt = PCNT::regs();
pcnt.u_cnt(NUM).read().cnt().bits() as i16
}
}