RE: Re: Rabbit 2000

[ian.bird@xxxxxxxxxxxxxx]

This is my design for a counter. In practice it has been working
reliably
but I don't have a flashy meter to try for real

Ian







"Paul Smith" <ukha@xxxxxxx>
Sent by: ukha_d@xxxxxxx
31/03/2006 14:37
Please respond to ukha_d


To:     <ukha_d@xxxxxxx>
cc:     (bcc: Ian Bird/CV/Novartis)
Subject:        RE: [ukha_d] Re: Rabbit 2000


>
> Looks a bit better!
> If I was you, I would use an interrupt driven input rather than
> polling. Polling can be made to work, but you must sample at at least
> twice the frequency of the pulse you are looking to measure, and it
> can all get a bit messy if your mark-space ratio is not even (which is
> pretty likely in a measuring meter led pulse scenario).
>
> For details on setting up an edge triggered interrupt, see here:
>
> http://www.rabbitsemiconductor.com/documentation/docs/manuals/Rabbit2000/U
> sersManual/index.htm
>
> section 7.9.1 is the relevant bit
>
> If I remember correctly, the rabbit sample code that comes with the
> compiler also includes some examples of how to do this too (or
> something pretty close to it)?
>
> PPS. Do publish the finished design, quite fancy one of these myself
:-)
>
> Cheers
> Patrick

Hi Patrick,

That's a problem for me as what I am trying to do is
monitor at least 3 inputs and the TN note from rabbit which hi-lights the
2000 module interrupt problem and says "This is done by using an
interrupt
routine that is driven continuously by a timer, and using that
routine to examine a number of input lines that can be considered to be
interrupt requests. The synthetic
interrupt can be edge or level sensitive. When a condition is detected
requiring a synthetic interrupt, the
routine calls the interrupt service routine.
This technique is more robust and requires less hardware than using hard
interrupts. It is especially good
for counting pulses and can be used to count a number of input pulse
streams at the same time. Experience
shows that counting pulses by using an interrupt input is an endless
source of trouble because of ill-conditioning
of the pulses and exceptions that often happen at the start and end of the
pulse train."

I've contacted rabbit for an example but they've not come back to me :-)

Any ideas ?

Regards,

Paul


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