Alternate Function Configuration; Figure 21. Output Configuration; Figure 22. Alternate Function Configuration - ST STM32F446 Series Reference Manual

General-purpose I/Os (GPIO)
7.3.11

Alternate function configuration

When the I/O port is programmed as alternate function:
•
The output buffer can be configured as open-drain or push-pull
•
The output buffer is driven by the signal 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 AHB1
clock cycle
•
A read access to the input data register gets the I/O state
Figure 22
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Figure 21. Output configuration

shows the Alternate function configuration of the I/O port bit.

Figure 22. Alternate function configuration

RM0390 Rev 4
RM0390