1
  2
  3
  4
  5
  6
  7
  8
  9
 10
 11
 12
 13
 14
 15
 16
 17
 18
 19
 20
 21
 22
 23
 24
 25
 26
 27
 28
 29
 30
 31
 32
 33
 34
 35
 36
 37
 38
 39
 40
 41
 42
 43
 44
 45
 46
 47
 48
 49
 50
 51
 52
 53
 54
 55
 56
 57
 58
 59
 60
 61
 62
 63
 64
 65
 66
 67
 68
 69
 70
 71
 72
 73
 74
 75
 76
 77
 78
 79
 80
 81
 82
 83
 84
 85
 86
 87
 88
 89
 90
 91
 92
 93
 94
 95
 96
 97
 98
 99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176

//! Digital I/O

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::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 try_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 try_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 try_set_state(&mut self, state: PinState) -> Result<(), Self::Error> {
        match state {
            PinState::Low => self.try_set_low(),
            PinState::High => self.try_set_high(),
        }
    }
}

/// 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 try_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 try_is_set_low(&self) -> Result<bool, Self::Error>;
}

/// Output pin that can be toggled
///
/// 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.
pub trait ToggleableOutputPin {
    /// Error type
    type Error;

    /// Toggle pin output.
    fn try_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::{OutputPin, StatefulOutputPin, ToggleableOutputPin};
/// use embedded_hal::digital::toggleable;
/// use core::convert::Infallible;
///
/// /// A virtual output pin that exists purely in software
/// struct MyPin {
///     state: bool
/// }
///
/// impl OutputPin for MyPin {
///    type Error = Infallible;
///
///    fn try_set_low(&mut self) -> Result<(), Self::Error> {
///        self.state = false;
///        Ok(())
///    }
///    fn try_set_high(&mut self) -> Result<(), Self::Error> {
///        self.state = true;
///        Ok(())
///    }
/// }
///
/// impl StatefulOutputPin for MyPin {
///    fn try_is_set_low(&self) -> Result<bool, Self::Error> {
///        Ok(!self.state)
///    }
///    fn try_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.try_toggle().unwrap();
/// assert!(pin.try_is_set_high().unwrap());
/// pin.try_toggle().unwrap();
/// assert!(pin.try_is_set_low().unwrap());
/// ```
pub mod toggleable {
    use super::{OutputPin, StatefulOutputPin, ToggleableOutputPin};

    /// Software-driven `toggle()` implementation.
    pub trait Default: OutputPin + StatefulOutputPin {}

    impl<P> ToggleableOutputPin for P
    where
        P: Default,
    {
        type Error = P::Error;

        /// Toggle pin output
        fn try_toggle(&mut self) -> Result<(), Self::Error> {
            if self.try_is_set_low()? {
                self.try_set_high()
            } else {
                self.try_set_low()
            }
        }
    }
}

/// Single digital input pin
pub trait InputPin {
    /// Error type
    type Error;

    /// Is the input pin high?
    fn try_is_high(&self) -> Result<bool, Self::Error>;

    /// Is the input pin low?
    fn try_is_low(&self) -> Result<bool, Self::Error>;
}