Alternate Function Configuration; Figure 13. Output Configuration - ST STM32F102 Series Reference Manual

General-purpose and alternate-function I/Os (GPIOs and AFIOs)

Figure 13. Output configuration

Read
Write
Read/write
1. V
DD_FT
7.1.9

Alternate function configuration

When the I/O Port is programmed as Alternate Function:
●
The Output Buffer is turned on in Open Drain or Push-Pull configuration
● The Output Buffer is driven by the signal coming from the peripheral (alternate function
out)
●
The Schmitt Trigger Input is activated
●
The weak pull-up and pull-down resistors are disabled.
●
The data present on the I/O pin is sampled into the Input Data Register every APB2
clock cycle
●
A read access to the Input Data Register gets the I/O state in open drain mode
●
A read access to the Output Data register gets the last written value in Push-Pull mode
The Figure 14 on page 103
Also, refer to
A set of Alternate Function I/O registers allow you to remap some alternate functions to
different pins. Refer to
102/690
Input driver
Output driver
is a potential specific to five-volt tolerant I/Os and different from V
shows the Alternate Function Configuration of the I/O Port bit.
Section 7.4: AFIO registers on page 115
on
TTL Schmitt
trigger
V
DD
P-MOS
Output
control
N-MOS
V
SS
for further information.
V
or V
DD
Protection
diode
Protection
diode
V
SS
Push-pull or
Open-drain
.
DD
RM0008
(1)
DD_FT
I/O pin
ai14784