I want to know how isolated (with separate GND terminals) analog inputs can be given to the Duemilanove.
Plz reply. :-?
Analogue inputs are much harder to isolate than digital ones. However, the technique is the same use an opto isolator.
However, it is difficult to match the voltage span on the input to that presented on the output. To do that you will have to experiment with resistor values in the LED and the collector resistor. You need to look at the data sheets and also have an idea of what sort of input signal you have, thinks like voltage swing / impedance / current.