36.5.8 Inputs
The level on each I/O line of the I/O group x can be read through PIO_PDSRx/S_PIO_PDSRx. This register indicates the level of the I/O lines regardless of their configuration, whether uniquely as an input, or driven by the PIO Controller, or driven by a peripheral.
Reading the I/O line levels requires the clock of the PIO Controller to be enabled, otherwise PIO_PDSRx/S_PIO_PDSRx reads the levels present on the I/O line at the time the clock was disabled.
Note: For security reasons, when a peripheral is not selected to drive
an IO or be driven by an IO, its input is stuck at its inactive level.