Function sleep 

pub fn sleep(ticks: u32)

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.

Example

let mut stack1 = [0xDEADBEEF; 512];
let _ = create_thread(
    &mut stack1,
    || {
        loop {
            let _ = hprintln!("in task 1 !!");
            sleep(50);
        }
    });