RE: Re: Rabbit 2000

["Paul Smith" <ukha@xxxxxxxxxxxxx>]

> Hi Paul,
>=20
> > 	That=92s a problem for me as what I am trying to do is
> > monitor at least 3 inputs
>=20
> Apologies if I have grasped the wrong end of this thread, but as I
> understand it, you are trying to count pulses from utility meters.
>=20
> The problems as I understand them are that the pulses are quite short
> (hence
> your use of a 555 monostable to lengthen the pulses) and also the time
> between pulses varies greatly depending on usage.
>=20
> How about this as an alternative idea.....
>=20
> use the meter pulses to clock a Flip-Flop
>=20
> Pulse 1 - flipflop goes high
> Pulse 2 - flipflop goes low
> Pulse 3 - flipflop goes high
>=20
> etc
>=20
> I dont know what the maximum pulse rate is that you expect but
assuming i=
t
> is one pulse every 10 seconds then just look at each of the flipflops
mor=
e
> often than that eg every second.
>=20
> If the state of the flipflop is different to the last time you looked
at
> it,
> increment your count.
>=20
> That way you dont "have to be there" when the pulse happens,
you just nee=
d
> to know that it DID happen.
>=20
> Regards
>=20
> Keith
>=20

Hi Keith,

That=92s an idea, I think I am sampling around 200uS so since the pulses
ar=
e a few mS I think I'm ok. The monostable was just a way to create a nice
l=
ooking pulses from the varying resistance from the LDR.I can get over a
100=
per minute. But the water meter is different as I think it's a reed relay =
and can be on for a while if it happens to stop flowing at that point.

Anyway thanks for the input it's always something else I can try if I do
ke=
ep getting spurious counts.

Regards,
Paul


--=20
No virus found in this outgoing message.
Checked by AVG Anti-Virus.
Version: 7.1.384 / Virus Database: 268.3.3/298 - Release Date: 30/03/2006
=20