Add PWM SetDuty trait.

embedded-hal/src/lib.rs

@@ -80,6 +80,7 @@
 pub mod delay;
 pub mod digital;
 pub mod i2c;
+pub mod pwm;
 pub mod serial;
 pub mod spi;
 

embedded-hal/src/pwm.rs

@@ -0,0 +1,71 @@
+//! Pulse Width Modulation (PWM) traits
+
+/// Error
+pub trait Error: core::fmt::Debug {
+    /// Convert error to a generic error kind
+    ///
+    /// By using this method, errors freely defined by HAL implementations
+    /// can be converted to a set of generic errors upon which generic
+    /// code can act.
+    fn kind(&self) -> ErrorKind;
+}
+
+impl Error for core::convert::Infallible {
+    fn kind(&self) -> ErrorKind {
+        match *self {}
+    }
+}
+
+/// Error kind
+///
+/// This represents a common set of operation errors. HAL implementations are
+/// free to define more specific or additional error types. However, by providing
+/// a mapping to these common errors, generic code can still react to them.
+#[derive(Debug, Copy, Clone, Eq, PartialEq, Ord, PartialOrd, Hash)]
+#[non_exhaustive]
+pub enum ErrorKind {
+    /// A different error occurred. The original error may contain more information.
+    Other,
+}
+
+impl Error for ErrorKind {
+    fn kind(&self) -> ErrorKind {
+        *self
+    }
+}
+
+impl core::fmt::Display for ErrorKind {
+    fn fmt(&self, f: &mut core::fmt::Formatter<'_>) -> core::fmt::Result {
+        match self {
+            Self::Other => write!(
+                f,
+                "A different error occurred. The original error may contain more information"
+            ),
+        }
+    }
+}
+
+/// Error type trait
+///
+/// This just defines the error type, to be used by the other traits.
+pub trait ErrorType {
+    /// Error type
+    type Error: Error;
+}
+
+impl<T: ErrorType> ErrorType for &mut T {
+    type Error = T::Error;
+}
+
+/// Single PWM channel / pin
+pub trait SetDuty: ErrorType {
+    /// Set the duty cycle.
+    ///
+    /// `duty` is the duty cycle. Valid values span the entire `u16` range:
+    ///
+    /// - `duty = 0` is considered 0% duty, which makes the pin permanently low.
+    /// - `duty = u16::MAX` is considered 1000% duty, which makes the pin permanently high.
+    ///
+    /// Implementations must scale the duty value linearly to the range required by the hardware.
+    fn set_duty(&mut self, duty: u16) -> Self::Error;
+}