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//! Asynchronous shared SPI bus
//!
//! # Example (nrf52)
//!
//! ```rust
//! use embassy_embedded_hal::shared_bus::spi::SpiBusDevice;
//! use embassy::mutex::Mutex;
//! use embassy::blocking_mutex::raw::ThreadModeRawMutex;
//!
//! static SPI_BUS: Forever<Mutex<ThreadModeRawMutex, spim::Spim<SPI3>>> = Forever::new();
//! let mut config = spim::Config::default();
//! config.frequency = spim::Frequency::M32;
//! let irq = interrupt::take!(SPIM3);
//! let spi = spim::Spim::new_txonly(p.SPI3, irq, p.P0_15, p.P0_18, config);
//! let spi_bus = Mutex::<ThreadModeRawMutex, _>::new(spi);
//! let spi_bus = SPI_BUS.put(spi_bus);
//!
//! // Device 1, using embedded-hal-async compatible driver for ST7735 LCD display
//! let cs_pin1 = Output::new(p.P0_24, Level::Low, OutputDrive::Standard);
//! let spi_dev1 = SpiBusDevice::new(spi_bus, cs_pin1);
//! let display1 = ST7735::new(spi_dev1, dc1, rst1, Default::default(), 160, 128);
//!
//! // Device 2
//! let cs_pin2 = Output::new(p.P0_24, Level::Low, OutputDrive::Standard);
//! let spi_dev2 = SpiBusDevice::new(spi_bus, cs_pin2);
//! let display2 = ST7735::new(spi_dev2, dc2, rst2, Default::default(), 160, 128);
//! ```
use core::{fmt::Debug, future::Future};
use embassy::blocking_mutex::raw::RawMutex;
use embassy::mutex::Mutex;
use embedded_hal_1::digital::blocking::OutputPin;
use embedded_hal_1::spi::ErrorType;
use embedded_hal_async::spi;
#[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, M: RawMutex, BUS, CS> {
bus: &'a Mutex<M, BUS>,
cs: CS,
}
impl<'a, M: RawMutex, BUS, CS> SpiBusDevice<'a, M, BUS, CS> {
pub fn new(bus: &'a Mutex<M, BUS>, cs: CS) -> Self {
Self { bus, cs }
}
}
impl<'a, M: RawMutex, BUS, CS> spi::ErrorType for SpiBusDevice<'a, M, BUS, CS>
where
BUS: spi::ErrorType,
CS: OutputPin,
{
type Error = SpiBusDeviceError<BUS::Error, CS::Error>;
}
impl<M, BUS, CS> spi::SpiDevice for SpiBusDevice<'_, M, BUS, CS>
where
M: RawMutex + 'static,
BUS: spi::SpiBusFlush + 'static,
CS: OutputPin,
{
type Bus = BUS;
type TransactionFuture<'a, R, F, Fut> = impl Future<Output = Result<R, Self::Error>> + 'a
where
Self: 'a, R: 'a, F: FnOnce(*mut Self::Bus) -> Fut + 'a,
Fut: Future<Output = Result<R, <Self::Bus as ErrorType>::Error>> + 'a;
fn transaction<'a, R, F, Fut>(&'a mut self, f: F) -> Self::TransactionFuture<'a, R, F, Fut>
where
R: 'a,
F: FnOnce(*mut Self::Bus) -> Fut + 'a,
Fut: Future<Output = Result<R, <Self::Bus as ErrorType>::Error>> + 'a,
{
async move {
let mut bus = self.bus.lock().await;
self.cs.set_low().map_err(SpiBusDeviceError::Cs)?;
let f_res = f(&mut *bus).await;
// On failure, it's important to still flush and deassert CS.
let flush_res = bus.flush().await;
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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