Merge #239

239: Add try_set_state method for OutputPin r=therealprof a=eldruin

This is an implementation of #200 to gather some opinions and so we can either accept it or close the issue.
This was earlier discussed at #44.

I added a conversion from `bool` following the usual convention as well as an `ops::Not` implementation as suggested in #200, which seemed appropriate.

I also added a default implementation for the `try_set_state` method. This bears the question whether a default implementation for `try_set_high()` / `try_set_low()` by using `try_set_state()` would be useful, so that potential implementors can choose to implement less methods.

It should be noted that adding a default implementation for all 3 methods has the somewhat amusing property of generating an endless loop if none is overwritten.

Closes #200 

Co-authored-by: Diego Barrios Romero <[email protected]>

Author: bors[bot]

CHANGELOG.md

@@ -10,6 +10,7 @@ and this project adheres to [Semantic Versioning](http://semver.org/).
 
 ### Added
 - 10-bit addressing mode for I2C traits.
+- `try_set_state` method for `OutputPin` using an input `PinState` value.
 
 ### Changed
 

src/digital.rs

@@ -1,5 +1,45 @@
 //! 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
@@ -16,6 +56,17 @@ pub trait OutputPin {
     /// *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