Add an example of per-core state

FIXME: nightly only

rp2040-hal/Cargo.toml

@@ -203,6 +203,10 @@ required-features = ["critical-section-impl"]
 name = "multicore_polyblink"
 required-features = ["critical-section-impl"]
 
+[[example]]
+name = "multicore_percore_data"
+required-features = ["critical-section-impl", "thread_local"]
+
 [[example]]
 name = "pio_blink"
 required-features = ["critical-section-impl"]

rp2040-hal/examples/multicore_percore_data.rs

@@ -0,0 +1,166 @@
+//! # Multicore Blinking Example
+//!
+//! This application blinks two LEDs on GPIOs 2 and 3 at different rates (3Hz
+//! and 4Hz respectively.)
+//!
+//! See the `Cargo.toml` file for Copyright and licence details.
+#![no_std]
+//#![cfg(feature = "thread_local")]
+#![feature(thread_local)]
+#![no_main]
+
+use core::cell::RefCell;
+
+use cortex_m::delay::Delay;
+
+use hal::clocks::Clock;
+use hal::gpio::{DynPinId, FunctionSio, Pin, Pins, PullDown, SioOutput};
+use hal::multicore::{Multicore, Stack};
+use hal::sio::Sio;
+// Ensure we halt the program on panic (if we don't mention this crate it won't
+// be linked)
+use panic_halt as _;
+
+// Alias for our HAL crate
+use rp2040_hal as hal;
+
+// A shorter alias for the Peripheral Access Crate, which provides low-level
+// register access
+use hal::pac;
+
+// Some traits we need
+use embedded_hal::digital::StatefulOutputPin;
+
+/// 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;
+
+/// The frequency at which core 0 will blink its LED (Hz).
+const CORE0_FREQ: u32 = 3;
+/// The frequency at which core 1 will blink its LED (Hz).
+const CORE1_FREQ: u32 = 4;
+/// The delay between each toggle of core 0's LED (us).
+const CORE0_DELAY: u32 = 1_000_000 / CORE0_FREQ;
+/// The delay between each toggle of core 1's LED (us).
+const CORE1_DELAY: u32 = 1_000_000 / CORE1_FREQ;
+
+/// Stack for core 1
+///
+/// Core 0 gets its stack via the normal route - any memory not used by static
+/// values is reserved for stack and initialised by cortex-m-rt.
+/// To get the same for Core 1, we would need to compile everything separately
+/// and modify the linker file for both programs, and that's quite annoying.
+/// So instead, core1.spawn takes a [usize] which gets used for the stack.
+/// NOTE: We use the `Stack` struct here to ensure that it has 32-byte
+/// alignment, which allows the stack guard to take up the least amount of
+/// usable RAM.
+static mut CORE1_STACK: Stack<4096> = Stack::new();
+
+/// State for the blinker
+struct BlinkState {
+    led: Pin<DynPinId, FunctionSio<SioOutput>, PullDown>,
+    delay: Delay,
+    delay_time: u32,
+}
+
+/// Per core blinker state
+#[thread_local]
+static STATE: RefCell<Option<BlinkState>> = RefCell::new(None);
+
+/// Blink which ever LED with whatever delay, according to the per-core state.
+fn blinker() -> ! {
+    let mut state = STATE.borrow_mut();
+    let BlinkState {
+        led,
+        delay,
+        delay_time,
+    } = state.as_mut().unwrap();
+    loop {
+        led.toggle().unwrap();
+        delay.delay_us(*delay_time);
+    }
+}
+
+/// 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.
+#[rp2040_hal::entry]
+fn main() -> ! {
+    // Grab our singleton objects
+    let mut pac = pac::Peripherals::take().unwrap();
+    let core = pac::CorePeripherals::take().unwrap();
+
+    // Set up the watchdog driver - needed by the clock setup code
+    let mut watchdog = hal::watchdog::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();
+
+    let sys_freq = clocks.system_clock.freq().to_Hz();
+
+    // Set up the GPIO pins
+    let mut sio = Sio::new(pac.SIO);
+    let pins = Pins::new(
+        pac.IO_BANK0,
+        pac.PADS_BANK0,
+        sio.gpio_bank0,
+        &mut pac.RESETS,
+    );
+    let led1 = pins.gpio2.into_push_pull_output();
+    let led2 = pins.gpio3.into_push_pull_output();
+
+    // Start up the second core to blink the second LED
+    let mut mc = Multicore::new(&mut pac.PSM, &mut pac.PPB, &mut sio.fifo);
+    let cores = mc.cores();
+    let core1 = &mut cores[1];
+    core1
+        .spawn(unsafe { &mut CORE1_STACK.mem }, move || {
+            // Get the second core's copy of the `CorePeripherals`, which are per-core.
+            // Unfortunately, `cortex-m` doesn't support this properly right now,
+            // so we have to use `steal`.
+            let core = unsafe { pac::CorePeripherals::steal() };
+            // Set up the delay for the second core.
+            let delay = Delay::new(core.SYST, sys_freq);
+
+            STATE.borrow_mut().replace(BlinkState {
+                led: led2.into_dyn_pin(),
+                delay,
+                delay_time: CORE1_DELAY,
+            });
+
+            // Blink the second LED.
+            blinker();
+        })
+        .unwrap();
+
+    // Set up the delay for the first core.
+    let delay = Delay::new(core.SYST, sys_freq);
+
+    // Blink the first LED.
+    STATE.borrow_mut().replace(BlinkState {
+        led: led1.into_dyn_pin(),
+        delay,
+        delay_time: CORE0_DELAY,
+    });
+    blinker();
+}
+
+// End of file