Re: New driver for Amplicon PCI272 and PC272E

On Thursday 03 February 2005 07:30 am, Ian Abbott wrote:
> Hi,
>
> I've added a new driver (plus a helper driver) for the Amplicon PCI272
> and PC272E 72-channel DIO cards to Bugzilla (bug #128):
>
> https://cvs.comedi.org/cgi-bin/bugzilla/show_bug.cgi?id=128
>
> Feel free to point out all the errors, etc. :-)

Hi Ian, 

I don't want command support simulated by the driver.  The hardware doesn't 
really support input or output commands, just externally triggered 
interrupts.  It reminds me of the evil das-08 which claimed to support 
externally triggered a/d conversions, but really all it did was generate 
an interrupt and the actual a/d conversion was started by the cpu (with 
crappy unreliable timing as a result).   The driver should just expose the 
ability to externally generate interrupts, then the user-space program (or 
RT task) can do whatever it wants when an interrupt is triggered.  

Right now, I think the only existing driver that does something similar 
with externally triggered interrupts is comedi_parport.c, which just 
writes a 0 to the buffer every time it gets an external trigger.  A 
user-space program can then do a select() on the device file to get woken 
up whenever a trigger occurs.  This scheme is less than ideal, but good 
enough if you don't want to spend time figuring out how to extend comedi 
to better support externally triggered callbacks.

-- 
Frank