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//! Blocking shared SPI bus
use core::cell::RefCell;
use core::fmt::Debug;
use embedded_hal_1::digital::blocking::OutputPin;
use embedded_hal_1::spi;
use embedded_hal_1::spi::blocking::{SpiBusFlush, SpiDevice};
#[derive(Copy, Clone, Eq, PartialEq, Debug)]
pub enum SpiBusDeviceError<BUS, CS> {
Spi(BUS),
Cs(CS),
}
impl<BUS, CS> spi::Error for SpiBusDeviceError<BUS, CS>
where
BUS: spi::Error + Debug,
CS: Debug,
{
fn kind(&self) -> spi::ErrorKind {
match self {
Self::Spi(e) => e.kind(),
Self::Cs(_) => spi::ErrorKind::Other,
}
}
}
pub struct SpiBusDevice<'a, BUS, CS> {
bus: &'a RefCell<BUS>,
cs: CS,
}
impl<'a, BUS, CS> SpiBusDevice<'a, BUS, CS> {
pub fn new(bus: &'a RefCell<BUS>, cs: CS) -> Self {
Self { bus, cs }
}
}
impl<'a, BUS, CS> spi::ErrorType for SpiBusDevice<'a, BUS, CS>
where
BUS: spi::ErrorType,
CS: OutputPin,
{
type Error = SpiBusDeviceError<BUS::Error, CS::Error>;
}
impl<BUS, CS> SpiDevice for SpiBusDevice<'_, BUS, CS>
where
BUS: SpiBusFlush,
CS: OutputPin,
{
type Bus = BUS;
fn transaction<R>(&mut self, f: impl FnOnce(&mut Self::Bus) -> Result<R, BUS::Error>) -> Result<R, Self::Error> {
let mut bus = self.bus.borrow_mut();
self.cs.set_low().map_err(SpiBusDeviceError::Cs)?;
let f_res = f(&mut bus);
// On failure, it's important to still flush and deassert CS.
let flush_res = bus.flush();
let cs_res = self.cs.set_high();
let f_res = f_res.map_err(SpiBusDeviceError::Spi)?;
flush_res.map_err(SpiBusDeviceError::Spi)?;
cs_res.map_err(SpiBusDeviceError::Cs)?;
Ok(f_res)
}
}
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