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//! Digital I/O
//!
//! Version 2 / fallible traits. Infallible implementations should set Error to `!`.
use core::{convert::From, ops::Not};
/// Digital output pin state
///
/// Conversion from `bool` and logical negation are also implemented
/// for this type.
/// ```rust
/// # use embedded_hal::digital::v2::PinState;
/// let state = PinState::from(false);
/// assert_eq!(state, PinState::Low);
/// assert_eq!(!state, PinState::High);
/// ```
#[derive(Debug, PartialEq, Eq, Clone, Copy)]
pub enum PinState {
/// Low pin state
Low,
/// High pin state
High,
}
impl From<bool> for PinState {
fn from(value: bool) -> Self {
match value {
false => PinState::Low,
true => PinState::High,
}
}
}
impl Not for PinState {
type Output = PinState;
fn not(self) -> Self::Output {
match self {
PinState::High => PinState::Low,
PinState::Low => PinState::High,
}
}
}
/// Single digital push-pull output pin
pub trait OutputPin {
/// Error type
type Error;
/// Drives the pin low
///
/// *NOTE* the actual electrical state of the pin may not actually be low, e.g. due to external
/// electrical sources
fn set_low(&mut self) -> Result<(), Self::Error>;
/// Drives the pin high
///
/// *NOTE* the actual electrical state of the pin may not actually be high, e.g. due to external
/// electrical sources
fn set_high(&mut self) -> Result<(), Self::Error>;
/// Drives the pin high or low depending on the provided value
///
/// *NOTE* the actual electrical state of the pin may not actually be high or low, e.g. due to external
/// electrical sources
fn set_state(&mut self, state: PinState) -> Result<(), Self::Error> {
match state {
PinState::Low => self.set_low(),
PinState::High => self.set_high(),
}
}
}
/// Push-pull output pin that can read its output state
///
/// *This trait is available if embedded-hal is built with the `"unproven"` feature.*
#[cfg(feature = "unproven")]
pub trait StatefulOutputPin: OutputPin {
/// Is the pin in drive high mode?
///
/// *NOTE* this does *not* read the electrical state of the pin
fn is_set_high(&self) -> Result<bool, Self::Error>;
/// Is the pin in drive low mode?
///
/// *NOTE* this does *not* read the electrical state of the pin
fn is_set_low(&self) -> Result<bool, Self::Error>;
}
/// Output pin that can be toggled
///
/// *This trait is available if embedded-hal is built with the `"unproven"` feature.*
///
/// See [toggleable](toggleable) to use a software implementation if
/// both [OutputPin](trait.OutputPin.html) and
/// [StatefulOutputPin](trait.StatefulOutputPin.html) are
/// implemented. Otherwise, implement this using hardware mechanisms.
#[cfg(feature = "unproven")]
pub trait ToggleableOutputPin {
/// Error type
type Error;
/// Toggle pin output.
fn toggle(&mut self) -> Result<(), Self::Error>;
}
/// If you can read **and** write the output state, a pin is
/// toggleable by software.
///
/// ```
/// use embedded_hal::digital::v2::{OutputPin, StatefulOutputPin, ToggleableOutputPin};
/// use embedded_hal::digital::v2::toggleable;
///
/// /// A virtual output pin that exists purely in software
/// struct MyPin {
/// state: bool
/// }
///
/// impl OutputPin for MyPin {
/// type Error = void::Void;
///
/// fn set_low(&mut self) -> Result<(), Self::Error> {
/// self.state = false;
/// Ok(())
/// }
/// fn set_high(&mut self) -> Result<(), Self::Error> {
/// self.state = true;
/// Ok(())
/// }
/// }
///
/// impl StatefulOutputPin for MyPin {
/// fn is_set_low(&self) -> Result<bool, Self::Error> {
/// Ok(!self.state)
/// }
/// fn is_set_high(&self) -> Result<bool, Self::Error> {
/// Ok(self.state)
/// }
/// }
///
/// /// Opt-in to the software implementation.
/// impl toggleable::Default for MyPin {}
///
/// let mut pin = MyPin { state: false };
/// pin.toggle().unwrap();
/// assert!(pin.is_set_high().unwrap());
/// pin.toggle().unwrap();
/// assert!(pin.is_set_low().unwrap());
/// ```
#[cfg(feature = "unproven")]
pub mod toggleable {
use super::{OutputPin, StatefulOutputPin, ToggleableOutputPin};
/// Software-driven `toggle()` implementation.
///
/// *This trait is available if embedded-hal is built with the `"unproven"` feature.*
pub trait Default: OutputPin + StatefulOutputPin {}
impl<P> ToggleableOutputPin for P
where
P: Default,
{
type Error = P::Error;
/// Toggle pin output
fn toggle(&mut self) -> Result<(), Self::Error> {
if self.is_set_low()? {
self.set_high()
} else {
self.set_low()
}
}
}
}
/// Single digital input pin
///
/// *This trait is available if embedded-hal is built with the `"unproven"` feature.*
#[cfg(feature = "unproven")]
pub trait InputPin {
/// Error type
type Error;
/// Is the input pin high?
fn is_high(&self) -> Result<bool, Self::Error>;
/// Is the input pin low?
fn is_low(&self) -> Result<bool, Self::Error>;
}
/// Single pin that can switch from input to output mode, and vice-versa.
///
/// Example use (assumes the `Error` type is the same for the `IoPin`,
/// `InputPin`, and `OutputPin`):
///
/// *This trait is available if embedded-hal is built with the `"unproven"` feature.*
#[cfg(feature = "unproven")]
pub trait IoPin<TInput, TOutput>
where
TInput: InputPin + IoPin<TInput, TOutput>,
TOutput: OutputPin + IoPin<TInput, TOutput>,
{
/// Error type.
type Error;
/// Tries to convert this pin to input mode.
///
/// If the pin is already in input mode, this method should succeed.
fn into_input_pin(self) -> Result<TInput, Self::Error>;
/// Tries to convert this pin to output mode with the given initial state.
///
/// If the pin is already in the requested state, this method should
/// succeed.
fn into_output_pin(self, state: PinState) -> Result<TOutput, Self::Error>;
}