Figure 20. Output Configuration; Alternate Function Configuration - ST STM32L4x6 Reference Manual

RM0351
7.3.11

Alternate function configuration

When the I/O port is programmed as alternate function:
•
The output buffer can be configured in open-drain or push-pull mode
• The output buffer is driven by the signals coming from the peripheral (transmitter
enable and data)
•
The Schmitt trigger input is activated
•
The weak pull-up and pull-down resistors are activated or not 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
Note: The alternate function configuration described above is not applied when the selected
alternate function is a LCD function or a SWPMI_IO. In this case, the I/O, programmed as
an alternate function output, is configured as described in the analog configuration.
Figure 21

Figure 20. Output configuration

shows the Alternate function configuration of the I/O port bit.
DocID024597 Rev 3
General-purpose I/Os (GPIO)
261/1693
272