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Since there is quite a difference in which and how the pins are used, do I need a different version of the program for the Arduino?
a) The sensors are connected to Pin 10 and 11 on the original setup, but in the one here, they are both connected to a single analogue input. Is there any disadvantage in using just one input channel (especially considering that there are so many unused ones)?
b) The original setup uses pins 3 through 9 to drive the LCD, while this setup employs a shift register, and thus uses only pins 10, 11 and 13. Why not use the original wiring without the pin shift register?
c) The original setup uses pins 12 and 13 for the relay, while here we use 5 and 6. Do I have to change the Arduino BrewPi software, or does it have the flexibility to change pin configuration afterwards?
d) The design here omits the rotary encoder. Those can be had for a buck or two on eBay. Can I just hook one up on pins 0, 1 and 2 and have it work?
e) The original design has an input for the fridge door, which has been omitted in this design. What does the fridge door switch do in BrewPi? Can I just add that "sensor" as per the original shield?
f) I want to install the RPI, Arduino, Relay and power converter all in one box. Should I add a little fan for ventilation, or is that overkill?