utask_example_3.c

This is simple example of semaphor usage. See docs for more details.

#include "utask.h"
#include "leds.h"
#include "timer.h"
#include "uart.h"

void timer_isr()            //called 1000 times a second
{
  utask_sleep_process();
}

int uart_busy = 0;

void task_send_msg(utask* t)
{
    switch (t->istate)
    {
        case 0:
            utask_wait_zero(t,&uart_busy,1000); //wait for uart to be free, timeout 1000ms
            t->istate = 1;
            break;
            
        case 1:
            if (t->sleep != 0)      //task has been awakened, uart_busy == 0
            {
                uart_busy = 1;  //claim resource
                t->istate = 2;
            }
            else
                t->istate = 0;      //go to waiting loop again
            break
            
        case 2:
            //do yer stuff with uart
            /*
            .
            .
            .
            */
            break;
            
        case N-1:
            //and here
            /*
            .
            .
            .
            */
            break;
        
        case N:
            uart_busy =  0;     //free resource
            utask_sleep(t,5000);
            t->istate = 0;      //do that over and over again
            break;
    }
}

const char* strings[] = 
{
    "Oh hello!",
    "Howdy!",
    "Fhtagn?"
};


int main ()
{
    timer_init();
    uart_init();
    utask_init();
    
    utask* t;
    
    t = utask_add(task_send_msg);       //add task
    t->arg = 0;     //use 1st string
    
    t = utask_add(task_send_msg);       //and another one
    t->arg = 1;     //use 2nd string
    
    t = utask_add(task_send_msg);       //and another one
    t->arg = 2;     //use 3rd string
    
    while (1)
    {
        utask_schedule();
    }
    return 0;
}