Hi Fulko,
Are you saying you want to check these bits every 1 msec and if there is a
change then record the time and the change ?
If so, yes, you will be able to do this quite easily with rt-linux. You can
set up a periodic task that will read the parallel port every 1msec and then
check the bits and do whatever you need to do. If this is all that is going
on you'll have no trouble. The rt task could communicate via fifo or shared
memory to an application and the application could print status information
to the screen along with writing the required data and time to disk. Even
if there is a flood of changes, the fifo can be set up large enough (or
shared memory) to handle this.
If you need some example code, I have something simple that I hacked to
toggle bits on the parallel port to see the accuracy of the real time timer
functions.
Let me know --
Janet Estabridis
Electrical Engineer
NAWC Code 473E00D
China Lake, CA 93555
[EMAIL PROTECTED]
(760) 939-2896 FAX (760) 939 -3075
> -----Original Message-----
> From: Fulko van Westrenen [SMTP:[EMAIL PROTECTED]]
> Sent: Wednesday, September 15, 1999 6:38 AM
> To: [EMAIL PROTECTED]
> Subject: [rtl] data-logging through parallel port
>
> Hello,
>
> I have a problem that looks to me like a FAQ so I would like
> to know if someone knows the answer before I learn
> by extensive trial and error.
>
> For an experiment I have to read at least two signals (TTL),
> preferably more but eight at most, with <=1ms accuracy (the 1ms
> is essential, missing an event is ``unacceptable'').
> When the signal goes low (or high when that is easier), this
> event must be written to disk together with the time.
> The signal-rate is about 2Hz and one experiment lasts from 1-4 hours.
>
> It looks to me that the parallel port on a PC together with rtlinux
> can do the job but I'm not sure. Does someone have some experience
> with this and knows how it can be done?
>
> Thank you very much for your time and for any information you
> can give me.
>
> Sincerely,
>
> Fulko
>
> --
> Fulko van Westrenen
> email: [EMAIL PROTECTED]
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