Alternate Function Configuration; Figure 14. Output Configuration - ST STM32F100 Series Reference Manual

RM0041
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
Figure 15
Section 7.4: AFIO registers
A set of Alternate Function I/O registers allows the user to remap some alternate functions
to different pins. Refer to
General-purpose and alternate-function I/Os (GPIOs and AFIOs)

Figure 14. Output configuration

Input driver
Output driver
is a potential specific to 5-Volt tolerant I/Os, and different from V
shows the Alternate Function Configuration of the I/O Port bit. Also, refer to
for further information.
Section 7.3: Alternate function I/O and debug configuration
on
TTL Schmitt
trigger
Output
control
RM0041 Rev 6
V
DD
P-MOS
N-MOS
Push-pull or
V
SS Open-drain
.
DD
(1)
V
or V
DD DD_FT
Protection
diode
I/O pin
Protection
diode
V
SS
ai14784
(AFIO).
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