5V Output

I want to send out serial data whenever a switch on Pin 12 goes high. Do I require an external powe supply to apply the 5V on Pin 12 or is it possible to use the 5V output of the Arduino?

you can use the 5 volts on the arduino, just be sure to add some resistance to limit how much current can pass

Thanks. What about grounds? Do I wire from Pin 12 to 5V output to ground?

[edit]

Thanks. What about grounds? Do I wire from Pin 12 to 5V output to ground?

[/edit] I mean pin 12 to switch to 5V to ground.

http://roguescience.org/wordpress/?page_id=11

check that page out, you will want a pull down resistor if you want the pin to normally be low unless the button is pressed

its actually easier to do the opposite, using the AT chip's internal pull up resistors, so when the button is up the level is high, and low when pressed down

Perfect. That link is exactly what I needed. Thank you.