ST STM32F102 series User Manual

RM0008 General-purpose and alternate-function I/Os (GPIOs and AFIOs)
101/690
7.1.7 Input configuration
When the I/O Port is programmed as Input:
● The Output Buffer is disabled
● The Schmitt Trigger Input is activated
● The weak pull-up and pull-down resistors are activated or not depending on input
configuration (pull-up, pull-down or floating):
● 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 obtains the I/O State.
The Figure 12 on page 101 shows the Input Configuration of the I/O Port bit.
Figure 12. Input floating/pull up/pull down configurations
1. V
DD_FT
is a potential specific to five-volt tolerant I/Os and different from V
DD
.
7.1.8 Output configuration
When the I/O Port is programmed as Output:
● The Output Buffer is enabled:
– Open Drain Mode: A “0” in the Output register activates the N-MOS while 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 while a “1” in the
Output register activates the P-MOS.
● 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 13 on page 102 shows the Output configuration of the I/O Port bit.
I/O pin
TTL Schmitt
trigger
V
SS
V
DD
or V
DD_FT
(1)
protection
diode
protection
diode
on
input driver
output driver
Input data register
Output data register
Read/write
Read
Bit set/reset registers
Write
on/off
on/off
V
DD
V
SS
ai14783

ST STM32F102 series Specifications

General

Brand	ST
Model	STM32F102 series
Category	Microcontrollers
Language	English