APIO:

The APIO pins refer to Application Specific Input-Output. These pins are under control of the selected software application and perform dedicated functions. The user does not have direct control over the state or function of the APIO pins. Refer to Section 3.3 for more details about the function of the APIO pins for each application mode.

GPIO:

The GPIO pins refer to General Purpose Input-Output. These pins are available to the user at all times and each pin can be configured using the programming interface as either an input or an output. As an output, pins can be set to either a logic high or a logic low state. As an input, the current logical state present on the pin can be read. Refer to Section 5.1 for information on the software interface for the GPIO pins.

TRIG:

The TRIG pins refer to Trigger Input-Output. The direction and function of each trigger pin is described in Table 2.5.2-1 below.