Re: Help implementing counter

From: <imr_at_oersted.dtu.dk> · Date: Tue, 16 Dec 2003 15:31:06 +0100 (CET)

> Hi All!
>
>  I have a PCI DAS 08 board and it have an 8254 timer/counter that can
> count external events (and one of the channels an internal clock).

There are lots of cards named things like PCI DAS <number>, you would save
us sometime if you also state the vendor name of the card and the driver you are
using, I'mguessing it is ComputerBoards and "das08".

>  From what I see in the sources the 8254 stuff isn´t implemented in the
> driver and I need it to count some external events.

In my "das08.c" of Comedi 0.7.66
Line 61:
#include "8255.h"

Lines 438 and 439:
i8255_offset:	0,
i8254_offset:	4,

Lines from 881 to 888:
s=dev->subdevices+4;
/* 8255 */
if(thisboard->i8255_offset!=0){
	subdev_8255_init(dev,s,NULL,(unsigned long)(dev->iobase+
		thisboard->i8255_offset));
}else{
	s->type=COMEDI_SUBD_UNUSED;
}

You don't need to understand all this, but seeing so many references to
8254 and 8255I would assume it is implemented. The question is if the 8255 driver
supports your 8254or you actually have a 8255, but I would bet one of the two is right.

>  I was browsing the sources and found some cryptic notes about the
> counters implementation but doing:
>
> $ grep SUBD_COUNTER *

It doesn't have to use that label, necessarily.

>  Gives me nothing, so it looks like Comedi doesn´t implement any
>  counter.

I think you haven't looked much... ;-)

> I have Comedi 0.7.67 sources, should I get something newer in
>  order to
> find an example of a counter?
>  Can anybody guide me in the implementation?

 From what I saw in the driver I would try if subdevice #4 is a 8255
counter. Look in"drivers.txt" and "counter-spec" in "Documentation/comedi" to see how to
use it.
>  Should I implement it in other way?
>
> Thanks, SET
>
> --
> Salvador Eduardo Tropea (SET). (Electronics Engineer)
> Visit my home page: http://welcome.to/SetSoft or
> http://www.geocities.com/SiliconValley/Vista/6552/
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>
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>
>
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