RE: Re: Rabbit 2000

["Paul Smith" <ukha@xxxxxxxxxxxxx>]

> I think your basic progamming logic is probably right. Most
likely
> guess is that you need to balance the sample rate with pulse width you
> are looking to detect. You need to sample such that at least 2
> interrupts fall within either a low or high state for the shortest
> state of the three pulses you are sampling. This should allow you to
> unambiguously detect state. If your pulses are very short, look at
> stretching them with your conditioning circuitry. If you are using a
> 555 in a monostable configuration, if the pulse is stretched too far,
> you will never see any change in state at all (the monostable is
> repeatedly reset by the occurence of each new pulse, so there is no
> change in state on the output).
>=20
> Other tricks that can help debugging:
> - toggle spare output pins in your timer routine so that you can
"see"
> what is happening in terms of logic execution on the scope as your
> pulse is detected.
> - swap the pulse generating circuitry for a signal generator, if you
> have one - you know the pulse will be clean, you can control
> mark-space ratio and you can experiment with really slow frequency
> pulse counting which will be easier to follow on the scope
>=20
> HTH a bit,
> Patrick
>=20
>=20

Hi Patrick,

Do you think it would matter if I sampled say 10x the quicker than the plu=
ses it just that I have the timerb running at 200uSec and the pulse width
i=
s in the mSec size.

What I don=92t understand is that I have used a pc serial port to generate
=
pulses by switching on DTR every 1000ms, I the set a loop to run X times
an=
d rabbit sees then all, I have even set this to 100ms and rabbit still
runs=
ok. I hope that the de-coupling caps with have solved the issues. I'll run=
another test and see what happens.

Thanks for your help

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