Merge pull request #3159 from kalkyl/shared-bus

Add example for shared I2C and SPI buses

docs/pages/sharing_peripherals.adoc

@@ -127,4 +127,8 @@ async fn toggle_led(control: Sender<'static, ThreadModeRawMutex, LedState, 64>,
 This example replaces the Mutex with a Channel, and uses another task (the main loop) to drive the LED. The advantage of this approach is that only a single task references the peripheral, separating concerns. However, using a Mutex has a lower overhead and might be necessary if you need to ensure
 that the operation is completed before continuing to do other work in your task.
 
-An example showcasing more methods for sharing link:https://github.com/embassy-rs/embassy/blob/main/examples/rp/src/bin/sharing.rs[can be found here].
+An example showcasing more methods for sharing link:https://github.com/embassy-rs/embassy/blob/main/examples/rp/src/bin/sharing.rs[can be found here].
+
+== Sharing an I2C or SPI bus between multiple devices
+
+An example of how to deal with multiple devices sharing a common I2C or SPI bus link:https://github.com/embassy-rs/embassy/blob/main/examples/rp/src/bin/shared_bus.rs[can be found here].

examples/rp/src/bin/shared_bus.rs

@@ -0,0 +1,115 @@
+//! This example shows how to share (async) I2C and SPI buses between multiple devices.
+
+#![no_std]
+#![no_main]
+
+use defmt::*;
+use embassy_embedded_hal::shared_bus::asynch::i2c::I2cDevice;
+use embassy_embedded_hal::shared_bus::asynch::spi::SpiDevice;
+use embassy_executor::Spawner;
+use embassy_rp::bind_interrupts;
+use embassy_rp::gpio::{AnyPin, Level, Output};
+use embassy_rp::i2c::{self, I2c, InterruptHandler};
+use embassy_rp::peripherals::{I2C1, SPI1};
+use embassy_rp::spi::{self, Spi};
+use embassy_sync::blocking_mutex::raw::NoopRawMutex;
+use embassy_sync::mutex::Mutex;
+use embassy_time::Timer;
+use static_cell::StaticCell;
+use {defmt_rtt as _, panic_probe as _};
+
+type Spi1Bus = Mutex<NoopRawMutex, Spi<'static, SPI1, spi::Async>>;
+type I2c1Bus = Mutex<NoopRawMutex, I2c<'static, I2C1, i2c::Async>>;
+
+bind_interrupts!(struct Irqs {
+    I2C1_IRQ => InterruptHandler<I2C1>;
+});
+
+#[embassy_executor::main]
+async fn main(spawner: Spawner) {
+    let p = embassy_rp::init(Default::default());
+    info!("Here we go!");
+
+    // Shared I2C bus
+    let i2c = I2c::new_async(p.I2C1, p.PIN_15, p.PIN_14, Irqs, i2c::Config::default());
+    static I2C_BUS: StaticCell<I2c1Bus> = StaticCell::new();
+    let i2c_bus = I2C_BUS.init(Mutex::new(i2c));
+
+    spawner.must_spawn(i2c_task_a(i2c_bus));
+    spawner.must_spawn(i2c_task_b(i2c_bus));
+
+    // Shared SPI bus
+    let spi_cfg = spi::Config::default();
+    let spi = Spi::new(p.SPI1, p.PIN_10, p.PIN_11, p.PIN_12, p.DMA_CH0, p.DMA_CH1, spi_cfg);
+    static SPI_BUS: StaticCell<Spi1Bus> = StaticCell::new();
+    let spi_bus = SPI_BUS.init(Mutex::new(spi));
+
+    // Chip select pins for the SPI devices
+    let cs_a = Output::new(AnyPin::from(p.PIN_0), Level::High);
+    let cs_b = Output::new(AnyPin::from(p.PIN_1), Level::High);
+
+    spawner.must_spawn(spi_task_a(spi_bus, cs_a));
+    spawner.must_spawn(spi_task_b(spi_bus, cs_b));
+}
+
+#[embassy_executor::task]
+async fn i2c_task_a(i2c_bus: &'static I2c1Bus) {
+    let i2c_dev = I2cDevice::new(i2c_bus);
+    let _sensor = DummyI2cDeviceDriver::new(i2c_dev, 0xC0);
+    loop {
+        info!("i2c task A");
+        Timer::after_secs(1).await;
+    }
+}
+
+#[embassy_executor::task]
+async fn i2c_task_b(i2c_bus: &'static I2c1Bus) {
+    let i2c_dev = I2cDevice::new(i2c_bus);
+    let _sensor = DummyI2cDeviceDriver::new(i2c_dev, 0xDE);
+    loop {
+        info!("i2c task B");
+        Timer::after_secs(1).await;
+    }
+}
+
+#[embassy_executor::task]
+async fn spi_task_a(spi_bus: &'static Spi1Bus, cs: Output<'static>) {
+    let spi_dev = SpiDevice::new(spi_bus, cs);
+    let _sensor = DummySpiDeviceDriver::new(spi_dev);
+    loop {
+        info!("spi task A");
+        Timer::after_secs(1).await;
+    }
+}
+
+#[embassy_executor::task]
+async fn spi_task_b(spi_bus: &'static Spi1Bus, cs: Output<'static>) {
+    let spi_dev = SpiDevice::new(spi_bus, cs);
+    let _sensor = DummySpiDeviceDriver::new(spi_dev);
+    loop {
+        info!("spi task B");
+        Timer::after_secs(1).await;
+    }
+}
+
+// Dummy I2C device driver, using `embedded-hal-async`
+struct DummyI2cDeviceDriver<I2C: embedded_hal_async::i2c::I2c> {
+    _i2c: I2C,
+}
+
+impl<I2C: embedded_hal_async::i2c::I2c> DummyI2cDeviceDriver<I2C> {
+    fn new(i2c_dev: I2C, _address: u8) -> Self {
+        Self { _i2c: i2c_dev }
+    }
+}
+
+// Dummy SPI device driver, using `embedded-hal-async`
+struct DummySpiDeviceDriver<SPI: embedded_hal_async::spi::SpiDevice> {
+    _spi: SPI,
+}
+
+impl<SPI: embedded_hal_async::spi::SpiDevice> DummySpiDeviceDriver<SPI> {
+    fn new(spi_dev: SPI) -> Self {
+        Self { _spi: spi_dev }
+    }
+}