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//! Pulse Width Modulation

/// Pulse Width Modulation
///
/// # Examples
///
/// Use this interface to control the power output of some actuator
///
/// ```
/// extern crate embedded_hal as hal;
///
/// use hal::prelude::*;
///
/// fn main() {
///     let mut pwm: Pwm1 = {
///         // ..
/// #       Pwm1
///     };
///
///     pwm.try_set_period(1.khz()).unwrap();
///
///     let max_duty = pwm.try_get_max_duty().unwrap();
///
///     // brightest LED
///     pwm.try_set_duty(Channel::_1, max_duty).unwrap();
///
///     // dimmer LED
///     pwm.try_set_duty(Channel::_2, max_duty / 4).unwrap();
/// }
///
/// # use core::convert::Infallible;
/// # struct KiloHertz(u32);
/// # trait U32Ext { fn khz(self) -> KiloHertz; }
/// # impl U32Ext for u32 { fn khz(self) -> KiloHertz { KiloHertz(self) } }
/// # enum Channel { _1, _2 }
/// # struct Pwm1;
/// # impl hal::pwm::Pwm for Pwm1 {
/// #     type Error = Infallible;
/// #     type Channel = Channel;
/// #     type Time = KiloHertz;
/// #     type Duty = u16;
/// #     fn try_disable(&mut self, _: Channel) -> Result<(), Self::Error> { unimplemented!() }
/// #     fn try_enable(&mut self, _: Channel) -> Result<(), Self::Error> { unimplemented!() }
/// #     fn try_get_duty(&self, _: Channel) -> Result<u16, Self::Error> { unimplemented!() }
/// #     fn try_get_max_duty(&self) -> Result<u16, Self::Error> { Ok(0) }
/// #     fn try_set_duty(&mut self, _: Channel, _: u16) -> Result<(), Self::Error> { Ok(()) }
/// #     fn try_get_period(&self) -> Result<KiloHertz, Self::Error> { unimplemented!() }
/// #     fn try_set_period<T>(&mut self, _: T) -> Result<(), Self::Error> where T: Into<KiloHertz> { Ok(()) }
/// # }
/// ```
// unproven reason: pre-singletons API. The `PwmPin` trait seems more useful because it models independent
// PWM channels. Here a certain number of channels are multiplexed in a single implementer.
pub trait Pwm {
    /// Enumeration of `Pwm` errors
    type Error;

    /// Enumeration of channels that can be used with this `Pwm` interface
    ///
    /// If your `Pwm` interface has no channels you can use the type `()`
    /// here
    type Channel;

    /// A time unit that can be converted into a human time unit (e.g. seconds)
    type Time;

    /// Type for the `duty` methods
    ///
    /// The implementer is free to choose a float / percentage representation
    /// (e.g. `0.0 .. 1.0`) or an integer representation (e.g. `0 .. 65535`)
    type Duty;

    /// Disables a PWM `channel`
    fn try_disable(&mut self, channel: Self::Channel) -> Result<(), Self::Error>;

    /// Enables a PWM `channel`
    fn try_enable(&mut self, channel: Self::Channel) -> Result<(), Self::Error>;

    /// Returns the current PWM period
    fn try_get_period(&self) -> Result<Self::Time, Self::Error>;

    /// Returns the current duty cycle
    ///
    /// While the pin is transitioning to the new duty cycle after a `try_set_duty` call, this may
    /// return the old or the new duty cycle depending on the implementation.
    fn try_get_duty(&self, channel: Self::Channel) -> Result<Self::Duty, Self::Error>;

    /// Returns the maximum duty cycle value
    fn try_get_max_duty(&self) -> Result<Self::Duty, Self::Error>;

    /// Sets a new duty cycle
    fn try_set_duty(&mut self, channel: Self::Channel, duty: Self::Duty)
        -> Result<(), Self::Error>;

    /// Sets a new PWM period
    fn try_set_period<P>(&mut self, period: P) -> Result<(), Self::Error>
    where
        P: Into<Self::Time>;
}

/// A single PWM channel / pin
///
/// See `Pwm` for details
pub trait PwmPin {
    /// Enumeration of `PwmPin` errors
    type Error;

    /// Type for the `duty` methods
    ///
    /// The implementer is free to choose a float / percentage representation
    /// (e.g. `0.0 .. 1.0`) or an integer representation (e.g. `0 .. 65535`)
    type Duty;

    /// Disables a PWM `channel`
    fn try_disable(&mut self) -> Result<(), Self::Error>;

    /// Enables a PWM `channel`
    fn try_enable(&mut self) -> Result<(), Self::Error>;

    /// Returns the current duty cycle
    ///
    /// While the pin is transitioning to the new duty cycle after a `try_set_duty` call, this may
    /// return the old or the new duty cycle depending on the implementation.
    fn try_get_duty(&self) -> Result<Self::Duty, Self::Error>;

    /// Returns the maximum duty cycle value
    fn try_get_max_duty(&self) -> Result<Self::Duty, Self::Error>;

    /// Sets a new duty cycle
    fn try_set_duty(&mut self, duty: Self::Duty) -> Result<(), Self::Error>;
}