The MIO Reservation feature allows you to select the unused/unassigned MIO’s as
GPIO/AUX-IO. To select these, you are required to click the MIO PIN view
button from the toolbar and
then select GPIO/AUX-IO options in the External
Usage column for the respected MIO. If any MIO is allocated to a peripheral then that
MIO cannot be set as GPIO/AUX-IO, so its External Usage drop down is disabled.
If the MIO usage is GPIO, then you can set its output data as active-High or
active-Low and direction as In or Out. After boot, this value will be driven on IO when
it is set in Out direction. If the MIO usage is AUX-IO, only then you can set direction
as In/Out.
Figure 1. MIO I/O Reservation Settings
The IO-Configuration page also allows you to select 64 GPIO-EMIO pins in PMC domain and 32 GPIO-EMIO pins in PS domain. Upon enabling this, these pins will be exposed to the PL region.