The general purpose I/Os are very configurable and support many interfaces. Additionally, they support several voltages, from 1.2V up to 3.3V for inputs and outputs. The voltage types are defined by the corresponding VCCIO. The customer can also configure the drive strength, slew rate control, pull-up, and pull-down. Other input configuration options include a Schmidt trigger and choices of dual purpose I/O pins. Lastly both inputs and outputs have optional Double Data Rate registers.