Added an example for using alloc-cortex-m

rp2040-hal/Cargo.toml

@@ -64,6 +64,7 @@ futures = { version = "0.3.30", default-features = false, features = [
 defmt-rtt = "0.4.0"
 panic-probe = { version = "0.3.1", features = ["print-defmt"] }
 defmt = "0.3"
+embedded-alloc = "0.5.1"
 
 [features]
 # Minimal startup / runtime for Cortex-M microcontrollers
@@ -141,6 +142,10 @@ required-features = ["critical-section-impl"]
 name = "adc_fifo_poll"
 required-features = ["critical-section-impl"]
 
+[[example]]
+name = "alloc"
+required-features = ["critical-section-impl"]
+
 [[example]]
 name = "blinky"
 required-features = ["critical-section-impl"]

rp2040-hal/examples/alloc.rs

@@ -0,0 +1,123 @@
+//! # Alloc Example
+//!
+//! Uses alloc to create a Vec.
+//!
+//! This will blink an LED attached to GP25, which is the pin the Pico uses for
+//! the on-board LED. It may need to be adapted to your particular board layout
+//! and/or pin assignment.
+//!
+//! While blinkin the LED, it will continuously push to a `Vec`, which will
+//! eventually lead to a panic due to an out of memory condition.
+//!
+//! See the `Cargo.toml` file for Copyright and licence details.
+
+#![no_std]
+#![no_main]
+
+extern crate alloc;
+
+use alloc::vec::Vec;
+use embedded_alloc::Heap;
+
+// The macro for our start-up function
+use cortex_m_rt::entry;
+
+#[global_allocator]
+static ALLOCATOR: Heap = Heap::empty();
+
+// 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::delay::DelayNs;
+use embedded_hal::digital::OutputPin;
+
+/// 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;
+
+/// Entry point to our bare-metal application.
+///
+/// The `#[entry]` macro ensures the Cortex-M start-up code calls this function
+/// as soon as all global variables are initialised.
+///
+/// The function configures the RP2040 peripherals, then blinks the LED in an
+/// infinite loop.
+#[entry]
+fn main() -> ! {
+    {
+        use core::mem::MaybeUninit;
+        const HEAP_SIZE: usize = 1024;
+        static mut HEAP: [MaybeUninit<u8>; HEAP_SIZE] = [MaybeUninit::uninit(); HEAP_SIZE];
+        unsafe { ALLOCATOR.init(HEAP.as_ptr() as usize, HEAP_SIZE) }
+    }
+
+    // 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
+    //
+    // The default is to generate a 125 MHz system clock
+    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,
+    )
+    .ok()
+    .unwrap();
+
+    let mut timer = rp2040_hal::Timer::new(pac.TIMER, &mut pac.RESETS, &clocks);
+
+    // 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,
+    );
+
+    // Configure GPIO25 as an output
+    let mut led_pin = pins.gpio25.into_push_pull_output();
+
+    let mut xs = Vec::new();
+    xs.push(1);
+
+    // Blink the LED at 1 Hz
+    loop {
+        led_pin.set_high().unwrap();
+        let len = xs.len() as u32;
+        timer.delay_ms(100 * len);
+        xs.push(1);
+        led_pin.set_low().unwrap();
+        timer.delay_ms(100 * len);
+        xs.push(1);
+    }
+}
+
+// End of file