RTOS MicroC tasking

Question

I've been working on some RTOS MicroC project and whenever I've implemented some function it works just fine outside the task, but whenever I put in the task it just wouldn't do anything. I know I might not get answer to this, but any tips where to start looking would be a big help, thanks in advance.

a_sem = OSSemCreate(1);

static void AppTask1(void *p_arg)
{
    (void) p_arg;
    INT8U perr;
    while (1)
    {
        OSSemPend(a_sem, 0, &perr);
        planeAngles();// Functon that works outside the task
        OSSemPost(a_sem);
        OSTimeDly(OS_TICKS_PER_SEC/20);
    }
}

static void AppTask2(void *p_arg)
{
    (void) p_arg;
    INT8U perr;
    while (1)
    {
        OSSemPend(a_sem, 0, &perr);
        servoTurns(); // Functon that works outside the task
        OSSemPost(a_sem);
        OSTimeDly(OS_TICKS_PER_SEC/20);
    }
}

Answer 1

Somewhere in your code, before AppTask1 and AppTask2 are created, you should have a line of code like this:

OSSemCreate(a_sem, 1, &perr);

You are creating a semaphore, a_sem with an initial value of 1 so that the first task that calls OSSemPend will successfully acquire the semaphore.

Also, you should not block forever on OSSemPend. Wait for awhile and then check the error status:

OSSemPend(a_sem, 10, &perr);
if(perr == OS_ERR_NONE)
{
    /* You have the semaphore */
}
else
{
    /* Error! Maybe a timeout */
}

Answer 2

Both tasks wait on a semaphore, but it is not clear where that semaphore is initially given. It seems likely that neither task ever returns from the OSSemPend call.