Yeah, thanks, I was writing the following post just before you (tochinet) posted your reply:
I've found something at: http://arduino.cc/forum/index.php/topic,58324.0.html
, in particular:
Can you tell me if it is possible to isolate the data line from the sensor to the boards input pin with an optocoupler ?
That won't work in any simple scenario...
Both the Arduino and the DS1820 "hanging" on the data line need to be able to pull the data line low. The pin switches between being an input and being an output.
So it seems I can't connect the DS18B20 to IN1/2/3/4, since the connection needs to be bidirectional and the opto-isolator of course make it monodirectional.
I was thinking about moving the Dallas microlan away from P1 since I am planning to add an LCD to my system using the 3-wire protocol, and I meant to use A0, A1 and D2. I guess I will have to either get rid of the serial port, so that I can use D0 and D1, or use a 2-wire LCD protocol.