Crate cortexm_threads

A simple library for context-switching on ARM Cortex-M ( 0, 0+, 3, 4, 4F ) micro-processors

Supports pre-emptive, priority based switching

This project is meant for learning and should be used only at the user’s risk. For practical and mature rust alternatives, see Awesome Embedded Rust

Example:

See example crate on github

#![no_std]
#![no_main]

extern crate panic_semihosting;
use cortex_m::peripheral::syst::SystClkSource;
use cortex_m_rt::{entry, exception};
use cortex_m_semihosting::{hprintln};
use cortexm_threads::{init, create_thread, create_thread_with_config, sleep};

#[entry]
fn main() -> ! {
    let cp = cortex_m::Peripherals::take().unwrap();
    let mut syst = cp.SYST;
    syst.set_clock_source(SystClkSource::Core);
    syst.set_reload(80_000);
    syst.enable_counter();
    syst.enable_interrupt();

	let mut stack1 = [0xDEADBEEF; 512];
    let mut stack2 = [0xDEADBEEF; 512];
    let _ = create_thread(
        &mut stack1,
        || {
            loop {
                let _ = hprintln!("in task 1 !!");
                sleep(50); // sleep for 50 ticks
            }
        });
    let _ = create_thread_with_config(
        &mut stack2,
        || {
            loop {
                let _ = hprintln!("in task 2 !!");
                sleep(30); // sleep for 30 ticks
            }
        },
        0x01, // priority, higher numeric value means higher priority
        true  // privileged thread
		);
    init();
}

Statics

ERR_NO_CREATE_PRIV

Returned by create_thread or create_thread_with_config as Err(ERR_NO_CREATE_PRIV) if called from an unprivileged thread

ERR_STACK_TOO_SMALL

Returned by create_thread or create_thread_with_config as Err(ERR_STACK_TOO_SMALL) if array to be used as stack area is too small. Smallest size is 32 u32’s

ERR_TOO_MANY_THREADS

Returned by create_thread or create_thread_with_config as Err(ERR_TOO_MANY_THREADS) if creating a thread will cause more than 32 threads to exist (inclusing the idle thread) created by this library

Functions

SysTick

Handle a tick event. Typically, this would be called as SysTick handler, but can be called anytime. Call from thread handler code to yield and switch context.

create_thread

Create a thread with default configuration (lowest priority, unprivileged).

create_thread_with_config

Create a thread with explicit configuration

disable_threads

enable_threads

get_thread_id

Get id of current thread

init

Initialize the switcher system

sleep

Make current thread sleep for ticks ticks. Current thread will be put in Sleeping state and another thread will be scheduled immediately. Current thread will not be considered for scheduling until tick() is called at least tick times.