But If I want a pin to register a switch press, can I feed it +5V straight from Arduino,
If I was connecting a switch directly to Arduino I would feed the switch line through a low-value resistor - 100 Ohm or so.
Whats this 100? resistor all about?There's a 100? resistor we use to connect the input pin to either HIGH or LOW voltage. Why is it there? Well, lets say you accidentally set P2 to be an OUTPUT type pin, but then you connected it to 5V. If you write a LOW to the pin (0V) but its connected to HIGH (5V), you've basically caused a short circuit at that pin. This isn't very good for the pin and could damage it! The 100? resistor acts as a buffer, to protect the pin from short circuits.
that having the switch go to ground, and the pull-up be contained within the security of the PCB, is the vastly superior connection from an engineering (safety) point of view
Well I agree with you on that one.I discuss it here:-http://www.thebox.myzen.co.uk/Tutorial/Inputs.html
Do you not agree on the protective benefits of an extra resistor? ("condom-resistor"?)
here is however a rendering blunder
Quotehere is however a rendering blunderDepends on you browser, if you are using anything but IE let me know and I will look into it.