I built this 7-8 years back using only analog stuff, now its not working =
100% ok
anymore so now is a good time to upgrade it using a MCU.
And add some bells and whitles to make it upto date. Will add a RS232 =
port
so I can adjust values realtime when running the mashine.

Your idea would prolly work but sounds a bit like overkill to me ;)

> Would a hardware solution work?  Use the input to pulse a RC circuit =
(2 resistors
> and 1 cap).  Feed the cap voltage back to another input pin.  More =
pulses (1's) =3D
> more voltage across the cap.  At some point you would have your =
digital high on the
> 2nd input pin.  Would make it easy to adjust your trip-point (if you =
need to do
> that) on the fly but of course it uses more pins and external =
hardware.

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