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#![doc(html_root_url = "https://docs.rs/rotary-encoder-hal/0.2.1")]
//! # rotary-encoder-hal
//!
//! A platform agnostic rotary encoder library
//!
//! Built using [`embedded-hal`] traits
//!
//! [`embedded-hal`]: https://docs.rs/embedded-hal/0.2
#![deny(missing_docs)]
#![deny(warnings)]
#![no_std]
use either::Either;
use embedded_hal as hal;
use hal::digital::v2::InputPin;
/// Holds current/old state and both [`InputPin`](https://docs.rs/embedded-hal/0.2.3/embedded_hal/digital/v2/trait.InputPin.html)
#[derive(Clone, Debug, Eq, PartialEq)]
pub struct Rotary<A, B> {
pin_a: A,
pin_b: B,
state: u8,
}
/// The encoder direction is either `Clockwise`, `CounterClockwise`, or `None`
#[derive(Clone, Copy, Debug, Eq, PartialEq)]
pub enum Direction {
/// A clockwise turn
Clockwise,
/// A counterclockwise turn
CounterClockwise,
/// No change
None,
}
impl From<u8> for Direction {
fn from(s: u8) -> Self {
match s {
0b0001 | 0b0111 | 0b1000 | 0b1110 => Direction::Clockwise,
0b0010 | 0b0100 | 0b1011 | 0b1101 => Direction::CounterClockwise,
_ => Direction::None,
}
}
}
impl<A, B> Rotary<A, B>
where
A: InputPin,
B: InputPin,
{
/// Accepts two `InputPin`s, these will be read on every `update()`
/// [InputPin]: https://docs.rs/embedded-hal/0.2.3/embedded_hal/digital/v2/trait.InputPin.html
pub fn new(pin_a: A, pin_b: B) -> Self {
Self {
pin_a,
pin_b,
state: 0u8,
}
}
/// Call `update` to evaluate the next state of the encoder, propagates errors from `InputPin` read
pub fn update(&mut self) -> Result<Direction, Either<A::Error, B::Error>> {
// use mask to get previous state value
let mut s = self.state & 0b11;
// move in the new state
if self.pin_a.is_low().map_err(Either::Left)? {
s |= 0b100;
}
if self.pin_b.is_low().map_err(Either::Right)? {
s |= 0b1000;
}
// move new state in
self.state = s >> 2;
Ok(s.into())
}
}