Advantech RSB-4210 Evaluation Kit Manual do Utilizador descarregar pdf (Página 92)

RSB-4210 User Manual 84

fprintf(stderr, "Waiting 5 seconds for alarm...");

fflush(stderr);

/* This blocks until the alarm ring causes an interrupt

retval = read(fd, &data, sizeof(unsigned long));

if (retval == -1) {

perror("read");

exit(errno);

}

irqcount++;

fprintf(stderr, " okay. Alarm rang.\n");

/* Disable alarm interrupts */

retval = ioctl(fd, RTC_AIE_OFF, 0);

if (retval == -1) {

perror("RTC_AIE_OFF ioctl");

exit(errno);

}

test_PIE:

/* Read periodic IRQ rate */

retval = ioctl(fd, RTC_IRQP_READ, &tmp);

if (retval == -1) {

/* not all RTCs support periodic IRQs */

if (errno == ENOTTY) {

fprintf(stderr, "\nNo periodic IRQ support\n");

goto done;

}

perror("RTC_IRQP_READ ioctl");

exit(errno);

}

fprintf(stderr, "\nPeriodic IRQ rate is %ldHz.\n", tmp);

fprintf(stderr, "Counting 20 interrupts at:");

fflush(stderr);

/* The frequencies 128Hz, 256Hz, ... 8192Hz are only

allowed for root. */

for (tmp=2; tmp<=64; tmp*=2) {

retval = ioctl(fd, RTC_IRQP_SET, tmp);

if (retval == -1) {

/* not all RTCs can change their periodic IRQ

rate */

if (errno == ENOTTY) {

fprintf(stderr,

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Advantech RSB-4210 Evaluation Kit Manual do Utilizador Página 92