11.4.9 I/O Multiplexing with Multiple Peripherals

For some devices, particularly those with a small number of I/O pins, multiple peripheral functions may be multiplexed on each I/O pin.

The name of the I/O pin defines the priority of each function associated with the pin. The conceptual I/O pin has two multiplexed peripherals, Peripheral A and Peripheral B, and is named as PERA/PERB/PIO.

The I/O pin name is chosen because the user-assigned application can easily determine the priority of the functions assigned to the pin. Peripheral A has the highest priority for control of the pin. If Peripheral A and Peripheral B are enabled at the same time, Peripheral A will take control of the I/O pin.