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//! PIO backed quadrature encoder
use crate::gpio::Pull;
use crate::pio::{
Common, Config, Direction as PioDirection, FifoJoin, Instance, LoadedProgram, PioPin, ShiftDirection, StateMachine,
};
use crate::pio_programs::clock_divider::calculate_pio_clock_divider;
use crate::Peri;
/// This struct represents an Encoder program loaded into pio instruction memory.
pub struct PioEncoderProgram<'a, PIO: Instance> {
prg: LoadedProgram<'a, PIO>,
}
impl<'a, PIO: Instance> PioEncoderProgram<'a, PIO> {
/// Load the program into the given pio
pub fn new(common: &mut Common<'a, PIO>) -> Self {
let prg = pio::pio_asm!("wait 1 pin 1", "wait 0 pin 1", "in pins, 2", "push",);
let prg = common.load_program(&prg.program);
Self { prg }
}
}
/// Pio Backed quadrature encoder reader
pub struct PioEncoder<'d, T: Instance, const SM: usize> {
sm: StateMachine<'d, T, SM>,
}
impl<'d, T: Instance, const SM: usize> PioEncoder<'d, T, SM> {
/// Configure a state machine with the loaded [PioEncoderProgram]
pub fn new(
pio: &mut Common<'d, T>,
mut sm: StateMachine<'d, T, SM>,
pin_a: Peri<'d, impl PioPin>,
pin_b: Peri<'d, impl PioPin>,
program: &PioEncoderProgram<'d, T>,
) -> Self {
let mut pin_a = pio.make_pio_pin(pin_a);
let mut pin_b = pio.make_pio_pin(pin_b);
pin_a.set_pull(Pull::Up);
pin_b.set_pull(Pull::Up);
sm.set_pin_dirs(PioDirection::In, &[&pin_a, &pin_b]);
let mut cfg = Config::default();
cfg.set_in_pins(&[&pin_a, &pin_b]);
cfg.fifo_join = FifoJoin::RxOnly;
cfg.shift_in.direction = ShiftDirection::Left;
// Target 12.5 KHz PIO clock
cfg.clock_divider = calculate_pio_clock_divider(12_500);
cfg.use_program(&program.prg, &[]);
sm.set_config(&cfg);
sm.set_enable(true);
Self { sm }
}
/// Read a single count from the encoder
pub async fn read(&mut self) -> Direction {
loop {
match self.sm.rx().wait_pull().await {
0 => return Direction::CounterClockwise,
1 => return Direction::Clockwise,
_ => {}
}
}
}
}
/// Encoder Count Direction
pub enum Direction {
/// Encoder turned clockwise
Clockwise,
/// Encoder turned counter clockwise
CounterClockwise,
}
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