[sdiy] Opinions on input protection

[John Luciani]

I would use AHC logic which has 5V tolerant inputs when powered
from a 3.3V supply.

If you are going to rely on the protection diodes make sure to
check the uC specs. Some of the Atmel parts are 1mA. I believe
some of the TI MSP430 parts are around 4mA. I would limit the
current to a value much lower than the absolute max.

I prefer to rely on the protection diodes for a protection function
not a standard operating function.

(* jcl *)

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