EFI ignition pickup

[David Chambers]

Hi,
I am currently building a fuel injection computer based on a 68HC11 and
am having trouble getting a reliable pickup for RPM. I would like to
design the circuit so that it can be triggered from any sort of ignition
pulse. ie hall effect, optical, reluctor or good old points. I can
handle the first three inputs with a comparator input and a little bit
of filtering this works, but when i try to pickup off the points side of
an ignition coil i get lots of spurious pulses. Anyone have any ideas
for a general circuit that will work on any ignition system.
Thanks David