Unused I/O Pins By default, the I/O driver (output) and input buffer (input) are disabled (tri-state mode) at power on or reset, and thus the I/O pin can safely be left unconnected (floating). If the I/O pin is in a tri-state condition and connected to a node with a different voltage potential, a small leakage current can go through the pin. The same applies to an I/O pin configured as input, where the pin is connected to a voltage source (for example VDD/2). The input is then an undefined value of either
0 or 1.