Do I have to specify my unused pins as tristate or can I leave the default setting?
Yes! If you do not specify your unused pins to be tristate inputs you will likely encounter problems down the road, and you may damage the chip/board! The default setting has the unused pins driving ground as outputs. As you recall from class, if an output driving ground were connected to an output driving Vcc, a short would result and the hardware could be damaged. This could happen in the lab, so please specify the much safer tristate implementation for unused pins. Note that if you are unable to completely download your software to the board, it may be because your unused pins are driving ground. To change the unused pins setting, go to Processing->Compiler Settings…, click on the Chips & Devices tab, click the Device and Pin Options… button, click the Unused Pins tab, and specify Reserve all unused pins as Inputs, tri-stated.
