Add SPI example using embedded_hal_bus

Author: 9names

rp2040-hal-examples/Cargo.toml

@@ -22,6 +22,7 @@ dht-sensor = "0.2.1"
 embedded-alloc = "0.5.1"
 embedded-hal = "1.0.0"
 embedded-hal-async = "1.0.0"
+embedded-hal-bus = { version = "0.2.0", features = ["defmt-03"] }
 embedded_hal_0_2 = {package = "embedded-hal", version = "0.2.5", features = ["unproven"]}
 fugit = "0.3.6"
 futures = {version = "0.3.30", default-features = false, features = ["async-await"]}
@@ -32,5 +33,8 @@ panic-halt = "0.2.0"
 panic-probe = {version = "0.3.1", features = ["print-defmt"]}
 pio = "0.2.0"
 pio-proc = "0.2.0"
+# We aren't using this, but embedded-hal-bus 0.2 unconditionally requires atomics.
+# Should be fixed in e-h-b 0.3 via https://github.com/rust-embedded/embedded-hal/pull/607
+portable-atomic = { version = "1.7.0", features = ["critical-section"] }
 rp2040-boot2 = "0.3.0"
 rp2040-hal = {path = "../rp2040-hal", version = "0.10.0", features = ["binary-info", "critical-section-impl", "rt", "defmt"]}

rp2040-hal-examples/src/bin/spi_eh_bus.rs

@@ -0,0 +1,197 @@
+//! # SPI Bus example
+//!
+//! This application demonstrates how to construct a simple Spi Driver,
+//! and configure rp2040-hal's Spi peripheral to access it by utilising
+//! `ExclusiveDevice`` from `embedded_hal_bus`
+//!
+//!
+//! It may need to be adapted to your particular board layout and/or pin
+//! assignment.
+//!
+//! See the top-level `README.md` file for Copyright and license details.
+
+#![no_std]
+#![no_main]
+
+use embedded_hal::spi::Operation;
+use embedded_hal::spi::SpiDevice;
+use embedded_hal_bus::spi::ExclusiveDevice;
+// Ensure we halt the program on panic (if we don't mention this crate it won't
+// be linked)
+use panic_halt as _;
+
+use rp2040_hal::gpio::PinState;
+use rp2040_hal::uart::{DataBits, StopBits, UartConfig};
+// Alias for our HAL crate
+use rp2040_hal as hal;
+
+// Some traits we need
+use core::fmt::Write;
+use hal::clocks::Clock;
+use hal::fugit::RateExtU32;
+
+// A shorter alias for the Peripheral Access Crate, which provides low-level
+// register access
+use hal::pac;
+
+/// The linker will place this boot block at the start of our program image. We
+/// need this to help the ROM bootloader get our code up and running.
+/// Note: This boot block is not necessary when using a rp-hal based BSP
+/// as the BSPs already perform this step.
+#[link_section = ".boot2"]
+#[used]
+pub static BOOT2: [u8; 256] = rp2040_boot2::BOOT_LOADER_GENERIC_03H;
+
+/// External high-speed crystal on the Raspberry Pi Pico board is 12 MHz. Adjust
+/// if your board has a different frequency
+const XTAL_FREQ_HZ: u32 = 12_000_000u32;
+
+/// Our Spi device driver
+/// We need to use a generic here (SPI), because we want our driver to work for any other
+/// microcontroller that implements the embedded-hal Spi traits
+struct MySpiDriver<SPI> {
+    spi: SPI,
+}
+
+/// When things go wrong, we could return Error(()) but that wouldn't help anyone troubleshoot
+/// so we'll create an error type with additional info to return.
+#[derive(Copy, Clone, Debug)]
+enum MyError<SPI> {
+    Spi(SPI),
+    // Add other errors for your driver here.
+}
+
+/// Implementation of the business logic for the remote Spi IC
+impl<SPI> MySpiDriver<SPI>
+where
+    SPI: SpiDevice,
+{
+    /// Construct a new instance of Spi device driver
+    pub fn new(spi: SPI) -> Self {
+        Self { spi }
+    }
+
+    /// Our hypothetical Spi device has a register at 0x20, that accepts a u8 value
+    pub fn set_value(&mut self, value: u8) -> Result<(), MyError<SPI::Error>> {
+        self.spi
+            .transaction(&mut [Operation::Write(&[0x20, value])])
+            .map_err(MyError::Spi)?;
+
+        Ok(())
+    }
+
+    /// Our hypothetical Spi device has a register at 0x90, that we can read a 2 byte value from
+    pub fn get_value(&mut self) -> Result<[u8; 2], MyError<SPI::Error>> {
+        let mut buf = [0; 2];
+        self.spi
+            .transaction(&mut [Operation::Write(&[0x90]), Operation::Read(&mut buf)])
+            .map_err(MyError::Spi)?;
+
+        Ok(buf)
+    }
+}
+
+/// Entry point to our bare-metal application.
+///
+/// The `#[rp2040_hal::entry]` macro ensures the Cortex-M start-up code calls this function
+/// as soon as all global variables and the spinlock are initialised.
+///
+/// The function configures the RP2040 peripherals, then performs some example
+/// SPI transactions, then goes to sleep.
+#[rp2040_hal::entry]
+fn main() -> ! {
+    // Grab our singleton objects
+    let mut pac = pac::Peripherals::take().unwrap();
+
+    // Set up the watchdog driver - needed by the clock setup code
+    let mut watchdog = hal::Watchdog::new(pac.WATCHDOG);
+
+    // Configure the clocks
+    let clocks = hal::clocks::init_clocks_and_plls(
+        XTAL_FREQ_HZ,
+        pac.XOSC,
+        pac.CLOCKS,
+        pac.PLL_SYS,
+        pac.PLL_USB,
+        &mut pac.RESETS,
+        &mut watchdog,
+    )
+    .unwrap();
+
+    // The single-cycle I/O block controls our GPIO pins
+    let sio = hal::Sio::new(pac.SIO);
+
+    // Set the pins to their default state
+    let pins = hal::gpio::Pins::new(
+        pac.IO_BANK0,
+        pac.PADS_BANK0,
+        sio.gpio_bank0,
+        &mut pac.RESETS,
+    );
+
+    let timer = rp2040_hal::Timer::new(pac.TIMER, &mut pac.RESETS, &clocks);
+
+    let uart_pins = (
+        // UART TX (characters sent from RP2040) on pin 1 (GPIO0)
+        pins.gpio0.into_function(),
+        // UART RX (characters received by RP2040) on pin 2 (GPIO1)
+        pins.gpio1.into_function(),
+    );
+
+    // Set up a uart so we can print out the values from our Spi peripheral
+    let mut uart = hal::uart::UartPeripheral::new(pac.UART0, uart_pins, &mut pac.RESETS)
+        .enable(
+            UartConfig::new(9600.Hz(), DataBits::Eight, None, StopBits::One),
+            clocks.peripheral_clock.freq(),
+        )
+        .unwrap();
+
+    // Set up our SPI pins so they can be used by the SPI driver
+    let spi_mosi = pins.gpio7.into_function::<hal::gpio::FunctionSpi>();
+    let spi_miso = pins.gpio4.into_function::<hal::gpio::FunctionSpi>();
+    let spi_sclk = pins.gpio6.into_function::<hal::gpio::FunctionSpi>();
+    let spi_cs = pins.gpio8.into_push_pull_output_in_state(PinState::High);
+    let spi = hal::spi::Spi::<_, _, _, 8>::new(pac.SPI0, (spi_mosi, spi_miso, spi_sclk));
+
+    // Exchange the uninitialised SPI driver for an initialised one
+    let spi = spi.init(
+        &mut pac.RESETS,
+        clocks.peripheral_clock.freq(),
+        16.MHz(),
+        embedded_hal::spi::MODE_0,
+    );
+
+    // We are the only task talking to this SPI peripheral, so we can use ExclusiveDevice here.
+    // If we had multiple tasks accessing this, you would need to use a different interface to
+    // ensure that we have exclusive access to this bus (via AtomicDevice or CriticalSectionDevice, for example)
+    // We can safely unwrap here, because the only possible failure is CS assertion failure, but our CS pin is infallible
+    let spi_bus = ExclusiveDevice::new(spi, spi_cs, timer).unwrap();
+
+    // Now that we've constructed a SpiDevice for our driver to use, we can finally construct our Spi driver
+    let mut driver = MySpiDriver::new(spi_bus);
+
+    match driver.set_value(10) {
+        Ok(_) => {
+            // Do something on success
+        }
+        Err(_) => {
+            // Do something on failure
+        }
+    }
+
+    match driver.get_value() {
+        Ok(value) => {
+            // Do something on success
+            writeln!(uart, "Read value was {} {}\n", value[0], value[1]).unwrap();
+        }
+        Err(_) => {
+            // Do something on failure
+        }
+    }
+
+    loop {
+        cortex_m::asm::wfi();
+    }
+}
+
+// End of file