I looked into the schematics of the Analogous board and I was wondering what the diods and the resistors where used for.
My guess is that the Diods are there to ensure that the tension coming from the jacks stays between +VCC and Ground.
This seems to be a security for the IC1, IC2 units and Atmega32. And it makes sure that all measures can be done by the Atmega32.
(but negative tensions aren't measured, then ?)
The R100 resistors seem to be there to support the switches in jacks (if they aren't there....the switch in the jack connect VCC and Ground...).
Maybee they are here to provide protection for the piezo elements too ?
Or, am I mistaken ?