Re: Rabbit 2000

["patrick_o_matic" <patrick@xxxxxxxxxxxx>]

--- In ukha_d@xxxxxxx, "Paul Smith" <ukha@...> wrote:
>
> Hi Guys,
>
>
>
>             I know several of you have used the rabbit devices and I
was
> wondering what you have done about the circuit boards you have
connected
> them too.
>
> I have the basic dev board but can't see the point of having single
> holes which go nowhere. I'm trying to get rabbit to count pulses from
> the electric meter(flashes) and pluses from the water metre. I have
got
> a circuit and software working but am suffering from a noise problem.
> Which I think is caused by the links from my breadboard to the rabbit
> dev board.
>

Pretty unlikely I think - much more likely to be caused by dirty/noisy
power rails. Try decoupling the power rails around your pulse counting
circuitry using 100nF caps. If you have access to a scope you make
also want to look at the shape of the conditioned pulses that you are
counting - you may need to add a schmidt trigger or similar to prevent
false triggers if the leading or trailing edge is rising slowly (and
you should be edge triggering, not level triggering, in this kind of
application).

Cheers
Patrick