On Thu, May 04, 2000 at 02:34:44PM -0400, Elliott Wolin wrote:
> Hi,
>
> I must be missing something fundamental. I don't know why the program below
> doesn't generate a single rectangular pulse on the parallel port with a width of
> 50 microsec. (rtlinux 2.2.13, PIII 450).
>
> Rather than the 2nd thread running 50 microsec after the 1st, it runs
> immediately after the 1st, giving 10 microsec pulses.
>
> How do you delay the startup of a thread?
You gave them 0 period and RTL scheduler picked a semi-safe 10microseconds
Try making the period 50000 -- see below.
>
>
> Sincerely,
> Elliott Wolin
>
>
> ===================================================================================
>
>
> /* Produce a single rectangular pulse on parallel port */
>
> #include <asm/io.h>
> #include <rtl.h>
> #include <pthread.h>
>
> #define LPT_PORT 0x378
>
> pthread_t t1,t2;
>
>
> void *fun(void *arg) {
> outb((int)arg, LPT_PORT);
> return(0);
> }
>
>
> int init_module(void) {
> pthread_create (&t1, NULL, fun, (void*)~0x0); /* rising edge */
> pthread_create (&t2, NULL, fun, (void*) 0x0); /* falling edge */
>
> /* pulse width is 50 microsec */
> pthread_make_periodic_np (t1, gethrtime(), 0); /* rising edge */
50000
> pthread_make_periodic_np (t2, gethrtime()+50000, 0); /* falling edge */
50000
>
> return(0);
> }
>
>
> void cleanup_module(void) {
> pthread_delete_np (t1);
> pthread_delete_np (t2);
> }
Content-Description: Card for Elliott Wolin
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