[sdiy] Opinions on input protection

[Joe Grisso]

Hey all,

     I've been thinking a lot about how to interface general trigger
and gate signals into interior digital logic, and wanted to get some
opinions from the group. This specifically applies to when you're
taking an external binary signal (0/5V, etc) and sending it into a 5V
or 3.3V micro. There are many methods of input protection including
suppression diodes, using a transistor as a switch, or even just
running the input into a logic buffer and using the internal
protection circuit of the IC to shift the 0-10V gate/trig signal down
to something the processor can digest without committing seppuku. I've
seen each of these methods used, either alone or together in some
larger configuration. What does everyone prefer here?

Best,

-- 
Joe Grisso
Detachment 3 Engineering