RM0313 Datasheet, PDF (145/900 Pages) STMicroelectronics – This reference manual targets application developers

RM0313
General-purpose I/Os (GPIO)
Figure 17. Output configuration
8.3.11
2EAD
7RITE
2EADWRITE
ON
44,3CHMITT
TRIGGER
)NPUTDRIVER
/UTPUTDRIVER
/UTPUT
CONTROL
6_$$ ⁶$$
ONOFF
PROTECTION
PULL
DIODE
UP
6_$$
ONOFF
)/PIN
0 -/3
. -/3
0USH PULLOR
6₃₃
/PEN DRAIN
PULL ^PROTECTION
DOWN DIODE
6₃₃
6₃₃
AIB
Alternate function configuration
When the I/O port is programmed as alternate function:
• The output buffer can be configured in open-drain or push-pull mode
• The output buffer is driven by the signals coming from the peripheral (transmitter
enable and data)
• The Schmitt trigger input is activated
• The weak pull-up and pull-down resistors are activated or not depending on the value
in the GPIOx_PUPDR register
• The data present on the I/O pin are sampled into the input data register every AHB
clock cycle
• A read access to the input data register gets the I/O state
Figure 18 shows the Alternate function configuration of the I/O port bit.
Figure 18. Alternate function configuration
4OON CHIP
PERIPHERAL
!LTERNATEFUNCTIONINPUT
2EAD
7RITE
ON
44,3CHMITT
TRIGGER
)NPUTDRIVER
/UTPUTDRIVER
2EADWRITE
&ROMON CHIP
PERIPHERAL
!LTERNATEFUNCTIONOUTPUT
/UTPUT
CONTROL
6_$$
0 -/3
. -/3
6₃₃
PUSH PULLOR
OPEN DRAIN
6_$$ ^6$$
ONOFF
0ULL
UP
PROTECTION
DIODE
ONOFF
)/PIN
0ULL
DOWN
PROTECTION
DIODE
6_{33 633}
AIB
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