NXP Semiconductors K22F series, Reference Manual, Page: 1382 / 1407

GPIOx_PDDR field descriptions (continued)
Field Description
50.3 Functional description
50.3.1 General-purpose input
The logic state of each pin is available via the Port Data Input registers, provided the pin
is configured for a digital function and the corresponding Port Control and Interrupt
module is enabled.
The Port Data Input registers return the synchronized pin state after any enabled digital
filter in the Port Control and Interrupt module. The input pin synchronizers are shared
with the Port Control and Interrupt module, so that if the corresponding Port Control and
Interrupt module is disabled, then synchronizers are also disabled. This reduces power
consumption when a port is not required for general-purpose input functionality.
50.3.2 General-purpose output
The logic state of each pin can be controlled via the port data output registers and port
data direction registers, provided the pin is configured for the GPIO function. The
following table depicts the conditions for a pin to be configured as input/output.
If Then
A pin is configured for the GPIO function and the
corresponding port data direction register bit is clear. The pin is configured as an input.
A pin is configured for the GPIO function and the
corresponding port data direction register bit is set. The pin is configured as an output and and the logic state of
the pin is equal to the corresponding port data output register.
To facilitate efficient bit manipulation on the general-purpose outputs, pin data set, pin
data clear, and pin data toggle registers exist to allow one or more outputs within one port
to be set, cleared, or toggled from a single register write.
The corresponding Port Control and Interrupt module does not need to be enabled to
update the state of the port data direction registers and port data output registers including
the set/clear/toggle registers.
Functional description
K22F Sub-Family Reference Manual, Rev. 4, 08/2016
1382 NXP Semiconductors