ST STM32F301 6 Series Reference Manual page 134

General-purpose I/Os (GPIO)
Figure 18
To on-chip
peripheral
Read
Write
Read/write
From on-chip
peripheral
8.3.12 Analog configuration
When the I/O port is programmed as analog configuration:
•
The output buffer is disabled
•
The Schmitt trigger input is deactivated, providing zero consumption for every analog
value of the I/O pin. The output of the Schmitt trigger is forced to a constant value (0).
•
The weak pull-up and pull-down resistors are disabled by hardware
•
Read access to the input data register gets the value "0"
Figure 19
To on-chip
peripheral
Read
Write
Read/write
From on-chip
peripheral
134/874
shows the alternate function configuration of the I/O port bit.
Figure 18. Alternate function configuration
Alternate function input
Alternate function output
shows the high-impedance, analog-input configuration of the I/O port bits.
Figure 19. High impedance-analog configuration
Analog
Analog
on
TTL Schmitt
trigger
Input driver
Output driver
Output
control
off
0
TTL Schmitt
trigger
Input driver
RM0366 Rev 5
V
DD
on/off
Pull
on/off
V
DD
Pull
P-MOS
down
V
SS
N-MOS
push-pull or
V
SS
open-drain
RM0366
V
DD
protection
diode
up
I/O pin
protection
diode
V
SS
ai15942b
V
DD
protection
diode
I/O pin
protection
diode
V
SS
ai15943