I am going to make some optocoupler interfaced inputs on my AVR
and i am trying to use (borrow the ideas from) this schematic.
Its an Olimex board , that has 4 optocoupler inputs.
What i dont understand is the 1N4148 across the input , why is it there ??
is it just a protection if you reverse the VCC so that it is on the lower side or ????
Thank you for any hints/help