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Figure 18 I/O Structure in Output Mode
Bit set/clear
register
Output
control
Output data
register
V
DD
V
SS
Read-write
Multiplexing function output
From on-chip
peripheral
Push-pull,
open-drain,
disable
P-MOS
N-MOS
Write
V
DDIOx
V
SS
I/O pin
PULL
UP
PULL
DOWN
Multiplexing Mode
In multiplexing mode, it can be set as push-pull multiplexing and open-drain
multiplexing
In push-pull/open-drain multiplexed mode:
Open the output buffer
Output buffer is driven by peripheral
Activate schmitt trigger input
By configuring the pull-up/pull-down register GPIOx_PUPD, select
whether to use pull-up/pull-down resistors
The data on the I/O pin is sampled in each AHB clock cycle and stored
in the port input state register
Read the actual I/O state through the input data register GPIOx_IDATA
Figure 19 I/O Structure in Multiplexing Mode
Output
control
V
DD
V
SS
Push-pull,
open-drain,
disable
P-MOS
N-MOS
I/O pin
TTL Schmitt
trigger
Multiplexing function output
Multiplexing function input
V
DDIOx
V
SS
PULL
UP
PULL
DOWN
Analog Mode
In analog function mode:
Disable output buffer
The input of Schmitt trigger is disabled, and the output value of Schmitt
trigger is forced to be 0
