Re: PCIDAS 4020/12 ext trigger/clock

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On Monday 20 December 2004 11:49 am, Nick Iorio wrote:
> I've posted this question at comedi.org and not received a response.  My
> boss keeps bugging me to get this external clock code working but I
> don't know how to do it.
> I found a reference to this INSN_CONFIG_TIMER_1 since I sent this email
> which helps some but still leaves a lot of questions.  Now, I guess the
> data structures should look like:
>
> data[0]=INSN_CONFIG_TIMER_1;
> data[1]=COMEDI_EV_SCAN_BEGIN;  correct?

Yes.  And you want to set your command's scan_begin_src to TRIG_OTHER.

> data[2]= ???  trigger negative edge (digital, not analog trigger)

That would be "channel_number | CR_INVERT | CR_EDGE".  The driver doesn't 
care though.  I assume I ignored that parameter in the driver because the 
hardware doesn't let you configure that.  I really should have added some 
verification that the hardware behaves the way you are requesting it to 
though.

> data[3]=0x04;
> data[4]=???  divisor for 10Mhz clock

If you set the divisor to N, then the board will trigger on every Nth clock 
signal it receives from your external clock.  The hardware's minimum 
divisor is 2.

>
> As you can see I'm still guessing on some of this.  If there's any
> documentation that would help me please point me to it.
>

there isn't any, aside from what you already found, and the driver source 
code.

- -- 
Frank

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Received on 2004-12-21Z01:17:59