5KHz acquisition control

[Till Straumann]

Not sure. Having a higher resolution system clock can be quite useful
since it allows you to use finer-grained timeouts (on semaphores, 
queues, sockets, ...)
or RTEMS timers etc. which can be desirable.

I have started to use a 1kHz clock by default on our MVME6100 boards
(1GHz powerpc) without noticeable impact on CPU load.

-- Till


On 06/07/2010 05:00 PM, Daron Chabot wrote:
> Matt,
>
> I've used a 455 MHz Pentium 3 interrupting at over 20 kHz as part of a 
> VME-based data acquisition system.
>
> I agree with Robert: if you can generate interrupts at the frequency 
> you need, _without_ using system's "ticks", that's the better 
> approach. Hopefully your ADC hardware can generate interrupts upon 
> conversion, or upon a "high-water-mark", or something similar...
>
> If that's not an option, you may be able to use one of the spare 
> timers on the i8254 chip (if your system is so equipped).
>
>
> -- dc
>
> On Mon, Jun 7, 2010 at 4:23 PM, Robert Deschambault 
> <robert.deschambault at gmail.com <mailto:robert.deschambault at gmail.com>> 
> wrote:
>
>     Hi,
>
>     In my opinion, I wouldn't run the RTEMS with a clock tick like
>     that, I would find a way to generate an external interrupt based
>     on a hardware timer.  I have successfully run RTEMS on a 40 MHz
>     LEON2, with no changes to the RTEMS clock ticks, to accept a 16
>     KHz interrupt signal for a fuzzy logic control loop to control a
>     gimbal.  Worked very well.
>
>
>     On Mon, Jun 7, 2010 at 4:12 PM, Matt Rippa <mrippa at gemini.edu
>     <mailto:mrippa at gemini.edu>> wrote:
>
>         Hi -
>
>         I would like to know your thoughts regarding common practices
>         for an RTEMS system requiring a 5 KHz sample rate. The
>         hardware is 600MHz i386/PC-104 based. Reading through the
>         RTEMS C users guide the Rate Monotonic Scheduler appears to be
>         what I'm interested in. Basically I need to read inputs from
>         hardware, filter and process results, then write outputs with
>         a period of 200 us.
>
>         I understand I can set the RTEMS system clock ticks to get
>         this resolution. My question is, is this a common and
>         recommend practice for this kind of sample rate? Or do people
>         favor using on-board programmable interrupt timers for this
>         purpose? Is using an external interrupt timer on the pci bus a
>         common practice if your SBC doesn't provide any timers?
>
>         Thanks for any input.
>
>         -Matt Rippa
>         _______________________________________________
>         rtems-users mailing list
>         rtems-users at rtems.org <mailto:rtems-users at rtems.org>
>         http://www.rtems.org/mailman/listinfo/rtems-users
>
>
>
>
>     -- 
>     Bob Deschambault
>     6614 Astro Court, Mississauga
>     Ontario, Canada L5N 7J2
>     home: 905 824 7159
>     cell: 416 457 7163
>
>     _______________________________________________
>     rtems-users mailing list
>     rtems-users at rtems.org <mailto:rtems-users at rtems.org>
>     http://www.rtems.org/mailman/listinfo/rtems-users
>
>
>
> _______________________________________________
> rtems-users mailing list
> rtems-users at rtems.org
> http://www.rtems.org/mailman/listinfo/rtems-users
>    

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.rtems.org/pipermail/users/attachments/20100607/877f1f94/attachment-0001.html>