AW: Using a trigger for multiple devices

From: Jan Klostermann <klostermann_at_rhf.de> · Date: Mon, 27 Sep 2004 09:57:10 +0200

Hi Bernd,

implementing a start trigger for the use within the device does not seem
too difficult - eventhough I did not really get the point yet, how to
implement these configurable triggers as described in the manual. 
The question is if it is possible to use such a trigger as external
trigger , probably TRIG_OTHER, in a completely different device and
therefore different module. How would I need to configure this other
device, how to tell him with trigger to use... (Maybe there is even some
driver enhancement necessary to enable it to use such "external" trigger
as start_src or stop_src, etc.)
Is there something like this supported or even already realized in some
driver to serve as example?
Or are there already any ideas around how to insert this kind of stuff
in the comedi framework?

Any comments are heavily appreceated.

Jan

-----Ursprüngliche Nachricht-----
Von: Bernd Porr [mailto:BerndPorr_at_f2s.com] 
Gesendet: Freitag, 24. September 2004 11:10
An: Jan Klostermann
Cc: comedi_at_comedi.org
Betreff: Re: Using a trigger for multiple devices

Jan,

it depends on the reaction time. You can poll the digital port by the 
standard dio commands and then start the asyncrounous acquistion.

However, some drivers support that feature internally with the flag 
TRIG_EXT. The argument is then the channel number.

It's on my todo list for our board. It's not very difficult. I thought 
about that in the context of an oscilloscope program. Like in an 
analogue oscilloscope you want to set a trigger which starts the 
acquisition.

/Bernd

www:    http://www.berndporr.me.uk/
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Jan Klostermann wrote:
> Hello!
> 
> I am wondering if the comedi framework supports software triggering 
> across several devices. Even if it might not be implemented in any 
> driver yet, is there a functionality implemented in the framework that

> allows to use a trigger event created by one hardware (e.g. a digital 
> input, possibly of the parallel port) to start/stop/whatoever the 
> acquisition of another device (e.g. an analog-DAQ via 
> comedi_command())?
> 
> It would be really cool having something like this...
> 
> Jan Klostermann
> 
> 
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