CAN support with bxcan crate

embassy-stm32/Cargo.toml

@@ -26,6 +26,7 @@ bare-metal = "1.0.0"
 atomic-polyfill = "0.1.3"
 stm32-metapac = { version = "0.1.0", path = "../stm32-metapac", features = ["rt"] }
 vcell = { version = "0.1.3", optional = true }
+bxcan = { version = "0.5.1" }
 
 cfg-if = "1.0.0"
 

embassy-stm32/src/can/bxcan.rs

@@ -0,0 +1,144 @@
+use core::marker::PhantomData;
+use core::ops::{Deref, DerefMut};
+
+use embassy::util::Unborrow;
+use embassy_hal_common::unborrow;
+
+use crate::gpio::Pin;
+use crate::{peripherals, rcc::RccPeripheral};
+
+pub use bxcan::*;
+
+pub struct Can<'d, T: Instance + bxcan::Instance> {
+    phantom: PhantomData<&'d mut T>,
+    can: bxcan::Can<T>,
+}
+
+impl<'d, T: Instance + bxcan::Instance> Can<'d, T> {
+    pub fn new(
+        peri: impl Unborrow<Target = T> + 'd,
+        rx: impl Unborrow<Target = impl RxPin<T>> + 'd,
+        tx: impl Unborrow<Target = impl TxPin<T>> + 'd,
+    ) -> Self {
+        unborrow!(peri, rx, tx);
+
+        unsafe {
+            rx.set_as_af(rx.af_num());
+            tx.set_as_af(tx.af_num());
+        }
+
+        T::enable();
+        T::reset();
+
+        Self {
+            phantom: PhantomData,
+            can: bxcan::Can::new(peri),
+        }
+    }
+}
+
+impl<'d, T: Instance + bxcan::Instance> Drop for Can<'d, T> {
+    fn drop(&mut self) {
+        // Cannot call `free()` because it moves the instance.
+        // Manually reset the peripheral.
+        unsafe {
+            T::regs().mcr().write(|w| w.set_reset(true));
+        }
+        T::disable();
+    }
+}
+
+impl<'d, T: Instance + bxcan::Instance> Deref for Can<'d, T> {
+    type Target = bxcan::Can<T>;
+
+    fn deref(&self) -> &Self::Target {
+        &self.can
+    }
+}
+
+impl<'d, T: Instance + bxcan::Instance> DerefMut for Can<'d, T> {
+    fn deref_mut(&mut self) -> &mut Self::Target {
+        &mut self.can
+    }
+}
+
+pub(crate) mod sealed {
+    use super::*;
+
+    pub trait Instance {
+        fn regs() -> &'static crate::pac::can::Can;
+    }
+
+    pub trait RxPin<T: Instance>: Pin {
+        fn af_num(&self) -> u8;
+    }
+
+    pub trait TxPin<T: Instance>: Pin {
+        fn af_num(&self) -> u8;
+    }
+}
+
+pub trait Instance: sealed::Instance + RccPeripheral {}
+pub trait RxPin<T: Instance>: sealed::RxPin<T> {}
+pub trait TxPin<T: Instance>: sealed::TxPin<T> {}
+
+crate::pac::peripherals!(
+    (can, $inst:ident) => {
+        impl sealed::Instance for peripherals::$inst {
+            fn regs() -> &'static crate::pac::can::Can {
+                &crate::pac::$inst
+            }
+        }
+
+        impl Instance for peripherals::$inst {}
+
+        unsafe impl bxcan::Instance for peripherals::$inst {
+            const REGISTERS: *mut bxcan::RegisterBlock = crate::pac::$inst.0 as *mut _;
+        }
+    };
+);
+
+crate::pac::peripherals!(
+    (can, CAN) => {
+        unsafe impl bxcan::FilterOwner for peripherals::$inst {
+            const NUM_FILTER_BANKS: u8 = 14;
+        }
+    };
+    // Only correct when CAN2 also exists… Fix on yaml level?
+    // There are only 14 filter banks when CAN2 is not available.
+    (can, CAN1) => {
+        unsafe impl bxcan::FilterOwner for peripherals::CAN1 {
+            const NUM_FILTER_BANKS: u8 = 28;
+        }
+    };
+    (can, CAN2) => {
+        // CAN2 is always a slave instance where CAN1 is the master instance
+        unsafe impl bxcan::MasterInstance for peripherals::CAN1 {}
+    };
+    (can, CAN3) => {
+        unsafe impl bxcan::FilterOwner for peripherals::$inst {
+            const NUM_FILTER_BANKS: u8 = 14;
+        }
+    };
+);
+
+macro_rules! impl_pin {
+    ($inst:ident, $pin:ident, $signal:ident, $af:expr) => {
+        impl $signal<peripherals::$inst> for peripherals::$pin {}
+
+        impl sealed::$signal<peripherals::$inst> for peripherals::$pin {
+            fn af_num(&self) -> u8 {
+                $af
+            }
+        }
+    };
+}
+
+crate::pac::peripheral_pins!(
+    ($inst:ident, can, CAN, $pin:ident, TX, $af:expr) => {
+        impl_pin!($inst, $pin, TxPin, $af);
+    };
+    ($inst:ident, can, CAN, $pin:ident, RX, $af:expr) => {
+        impl_pin!($inst, $pin, RxPin, $af);
+    };
+);

embassy-stm32/src/can/mod.rs

@@ -0,0 +1,5 @@
+#![macro_use]
+
+#[cfg_attr(can_bxcan, path = "bxcan.rs")]
+mod _version;
+pub use _version::*;

embassy-stm32/src/lib.rs

@@ -27,6 +27,8 @@ mod time_driver;
 
 #[cfg(adc)]
 pub mod adc;
+#[cfg(can)]
+pub mod can;
 #[cfg(dac)]
 pub mod dac;
 #[cfg(dbgmcu)]

examples/stm32f4/Cargo.toml

@@ -32,3 +32,4 @@ panic-probe = { version = "0.2.0", features= ["print-defmt"] }
 futures = { version = "0.3.8", default-features = false, features = ["async-await"] }
 rtt-target = { version = "0.3", features = ["cortex-m"] }
 heapless = { version = "0.7.1", default-features = false }
+nb = { version = "1.0" }

examples/stm32f4/src/bin/can.rs

@@ -0,0 +1,52 @@
+#![no_std]
+#![no_main]
+#![feature(trait_alias)]
+#![feature(type_alias_impl_trait)]
+#![allow(incomplete_features)]
+
+#[path = "../example_common.rs"]
+mod example_common;
+
+use cortex_m_rt::entry;
+use embassy_stm32::can::filter::Mask32;
+use embassy_stm32::can::{Can, Frame, StandardId};
+use embassy_stm32::dbgmcu::Dbgmcu;
+use embassy_stm32::gpio::{Input, Pull};
+use example_common::*;
+
+#[entry]
+fn main() -> ! {
+    info!("Hello World!");
+
+    unsafe {
+        Dbgmcu::enable_all();
+    }
+
+    let mut p = embassy_stm32::init(Default::default());
+
+    // The next two lines are a workaround for testing without transceiver.
+    // To synchronise to the bus the RX input needs to see a high level.
+    // Use `mem::forget()` to release the borrow on the pin but keep the
+    // pull-up resistor enabled.
+    let rx_pin = Input::new(&mut p.PA11, Pull::Up);
+    core::mem::forget(rx_pin);
+
+    let mut can = Can::new(p.CAN1, p.PA11, p.PA12);
+
+    can.modify_config()
+        .set_bit_timing(0x001c0003) // http://www.bittiming.can-wiki.info/
+        .set_loopback(true) // Receive own frames
+        .set_silent(true);
+    can.modify_filters().enable_bank(0, Mask32::accept_all());
+    unwrap!(nb::block!(can.enable()));
+
+    let mut i: u8 = 0;
+    loop {
+        let tx_frame = Frame::new_data(unwrap!(StandardId::new(i as _)), [i]);
+        unwrap!(nb::block!(can.transmit(&tx_frame)));
+        while !can.is_transmitter_idle() {}
+        let rx_frame = unwrap!(nb::block!(can.receive()));
+        info!("loopback frame {=u8}", unwrap!(rx_frame.data())[0]);
+        i += 1;
+    }
+}