Figure 19. Input Floating/Pull Up/Pull Down Configurations; Output Configuration - ST STM32L4x6 Reference Manual

General-purpose I/Os (GPIO)
7.3.10

Output configuration

When the I/O port is programmed as output:
•
The output buffer is enabled:
–
–
• The Schmitt trigger input is activated
•
The pull-up and pull-down resistors are activated depending on the value in the
GPIOx_PUPDR register
•
The data present on the I/O pin are sampled into the input data register every AHB
clock cycle
•
A read access to the input data register gets the I/O state
•
A read access to the output data register gets the last written value
Figure 20
260/1693

Figure 19. Input floating/pull up/pull down configurations

Open drain mode: A "0" in the Output register activates the N-MOS whereas a "1"
in the Output register leaves the port in Hi-Z (the P-MOS is never activated)
Push-pull mode: A "0" in the Output register activates the N-MOS whereas a "1" in
the Output register activates the P-MOS
shows the output configuration of the I/O port bit.
DocID024597 Rev 3
RM0351