[Linux-parport] interrupts with ppdev
chris at communityrenewables.com
Mon May 29 00:01:36 EDT 2006
I am trying to use ppdev in a userland program. It would be nice if I
could use the interrupt feature it supports. Its implementation is not
exactly clear to me. I read over Tim Waugh's paper several times. It
seems I need to write a "1" to the IRQ enable bit of the control
register. After that, interrupts are triggered by a negative going
pulse on the #ACK pin (pin 10). Well, that is not working for me. I
reviewed the archives of this list and noticed several other people
have had questions similar to mine, but nobody has replied.
here is basically what I am doing:
fd = open(name , O_RDWR); //name is /dev/parport0
ioctl (fd, PPCLAIM)
// Read the control register
theData = 0;
ioctl(fd, PPRCONTROL, &theData)
theData |= 0x10; //enable interrupts
ioctl(fd, PPWCONTROL, &theData)
//p. 25 Wait for an interrupt with poll.
code not shown for simplicity, but it is essentially straight from
/* this is where I connect a 10k resistor between pin 10 and ground. */
//check to see if an interrupt was sensed
ioctl(fd, PPCLRIRQ, &interruptCount)
...and interruptCount is always zero. That tells me the interrupt is
not being triggered. Hmm. I am out of ideas.
So, if we can get this working, I'll post the complete code back to the
list so that others can use it.
Thanks for your time,
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