embassy_stm32/timer/
qei.rs

1//! Quadrature decoder using a timer.
2
3use core::marker::PhantomData;
4
5use embassy_hal_internal::{into_ref, PeripheralRef};
6use stm32_metapac::timer::vals;
7
8use super::low_level::Timer;
9use super::{Channel1Pin, Channel2Pin, GeneralInstance4Channel};
10use crate::gpio::{AfType, AnyPin, Pull};
11use crate::Peripheral;
12
13/// Counting direction
14pub enum Direction {
15    /// Counting up.
16    Upcounting,
17    /// Counting down.
18    Downcounting,
19}
20
21/// Channel 1 marker type.
22pub enum Ch1 {}
23/// Channel 2 marker type.
24pub enum Ch2 {}
25
26/// Wrapper for using a pin with QEI.
27pub struct QeiPin<'d, T, Channel> {
28    _pin: PeripheralRef<'d, AnyPin>,
29    phantom: PhantomData<(T, Channel)>,
30}
31
32macro_rules! channel_impl {
33    ($new_chx:ident, $channel:ident, $pin_trait:ident) => {
34        impl<'d, T: GeneralInstance4Channel> QeiPin<'d, T, $channel> {
35            #[doc = concat!("Create a new ", stringify!($channel), " QEI pin instance.")]
36            pub fn $new_chx(pin: impl Peripheral<P = impl $pin_trait<T>> + 'd) -> Self {
37                into_ref!(pin);
38                critical_section::with(|_| {
39                    pin.set_low();
40                    pin.set_as_af(pin.af_num(), AfType::input(Pull::None));
41                });
42                QeiPin {
43                    _pin: pin.map_into(),
44                    phantom: PhantomData,
45                }
46            }
47        }
48    };
49}
50
51channel_impl!(new_ch1, Ch1, Channel1Pin);
52channel_impl!(new_ch2, Ch2, Channel2Pin);
53
54/// Quadrature decoder driver.
55pub struct Qei<'d, T: GeneralInstance4Channel> {
56    inner: Timer<'d, T>,
57}
58
59impl<'d, T: GeneralInstance4Channel> Qei<'d, T> {
60    /// Create a new quadrature decoder driver.
61    pub fn new(tim: impl Peripheral<P = T> + 'd, _ch1: QeiPin<'d, T, Ch1>, _ch2: QeiPin<'d, T, Ch2>) -> Self {
62        Self::new_inner(tim)
63    }
64
65    fn new_inner(tim: impl Peripheral<P = T> + 'd) -> Self {
66        let inner = Timer::new(tim);
67        let r = inner.regs_gp16();
68
69        // Configure TxC1 and TxC2 as captures
70        r.ccmr_input(0).modify(|w| {
71            w.set_ccs(0, vals::CcmrInputCcs::TI4);
72            w.set_ccs(1, vals::CcmrInputCcs::TI4);
73        });
74
75        // enable and configure to capture on rising edge
76        r.ccer().modify(|w| {
77            w.set_cce(0, true);
78            w.set_cce(1, true);
79
80            w.set_ccp(0, false);
81            w.set_ccp(1, false);
82        });
83
84        r.smcr().modify(|w| {
85            w.set_sms(vals::Sms::ENCODER_MODE_3);
86        });
87
88        r.arr().modify(|w| w.set_arr(u16::MAX));
89        r.cr1().modify(|w| w.set_cen(true));
90
91        Self { inner }
92    }
93
94    /// Get direction.
95    pub fn read_direction(&self) -> Direction {
96        match self.inner.regs_gp16().cr1().read().dir() {
97            vals::Dir::DOWN => Direction::Downcounting,
98            vals::Dir::UP => Direction::Upcounting,
99        }
100    }
101
102    /// Get count.
103    pub fn count(&self) -> u16 {
104        self.inner.regs_gp16().cnt().read().cnt()
105    }
106}
embassy_stm32/timer/qei.rs

embassy_stm32/timer/
qei.rs
