//! Digital I/O
use core::{convert::From, ops::Not};
/// GPIO error type trait
///
/// This just defines the error type, to be used by the other traits.
pub trait ErrorType {
/// Error type
type Error: core::fmt::Debug;
}
impl<T: ErrorType> ErrorType for &T {
type Error = T::Error;
}
impl<T: ErrorType> ErrorType for &mut T {
type Error = T::Error;
}
/// Digital output pin state
///
/// Conversion from `bool` and logical negation are also implemented
/// for this type.
/// ```rust
/// # use embedded_hal::digital::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,
}
}
}
/// Blocking digital I/O traits
pub mod blocking {
use super::PinState;
/// Single digital push-pull output pin
pub trait OutputPin: super::ErrorType {
/// 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(),
}
}
}
impl<T: OutputPin> OutputPin for &mut T {
fn set_low(&mut self) -> Result<(), Self::Error> {
T::set_low(self)
}
fn set_high(&mut self) -> Result<(), Self::Error> {
T::set_high(self)
}
fn set_state(&mut self, state: PinState) -> Result<(), Self::Error> {
T::set_state(self, state)
}
}
/// Push-pull output pin that can read its output state
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>;
}
impl<T: StatefulOutputPin> StatefulOutputPin for &mut T {
fn is_set_high(&self) -> Result<bool, Self::Error> {
T::is_set_high(self)
}
fn is_set_low(&self) -> Result<bool, Self::Error> {
T::is_set_low(self)
}
}
/// Output pin that can be toggled
pub trait ToggleableOutputPin: super::ErrorType {
/// Toggle pin output.
fn toggle(&mut self) -> Result<(), Self::Error>;
}
impl<T: ToggleableOutputPin> ToggleableOutputPin for &mut T {
fn toggle(&mut self) -> Result<(), Self::Error> {
T::toggle(self)
}
}
/// Single digital input pin
pub trait InputPin: super::ErrorType {
/// 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>;
}
impl<T: InputPin> InputPin for &T {
fn is_high(&self) -> Result<bool, Self::Error> {
T::is_high(self)
}
fn is_low(&self) -> Result<bool, Self::Error> {
T::is_low(self)
}
}
/// 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`):
///
/// ```
/// use core::time::Duration;
/// use embedded_hal::digital::blocking::{IoPin, InputPin, OutputPin};
///
/// pub fn ping_and_read<TInputPin, TOutputPin, TError: core::fmt::Debug>(
/// mut pin: TOutputPin, delay_fn: &dyn Fn(Duration) -> ()) -> Result<bool, TError>
/// where
/// TInputPin : InputPin<Error = TError> + IoPin<TInputPin, TOutputPin, Error = TError>,
/// TOutputPin : OutputPin<Error = TError> + IoPin<TInputPin, TOutputPin, Error = TError>,
/// {
/// // Ping
/// pin.set_low()?;
/// delay_fn(Duration::from_millis(10));
/// pin.set_high()?;
///
/// // Read
/// let pin = pin.into_input_pin()?;
/// delay_fn(Duration::from_millis(10));
/// pin.is_high()
/// }
/// ```
pub trait IoPin<TInput, TOutput>
where
TInput: InputPin + IoPin<TInput, TOutput>,
TOutput: OutputPin + IoPin<TInput, TOutput>,
{
/// Error type.
type Error: core::fmt::Debug;
/// 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>;
}
}