DocID018909 Rev 11
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RM0090
General-purpose I/Os (GPIO)
290
8.3.1 General-purpose
I/O
(GPIO)
During and just after reset, the alternate functions are not active and the I/O ports are
configured in input floating mode.
The debug pins are in AF pull-up/pull-down after reset:
•
PA15: JTDI in pull-up
•
PA14: JTCK/SWCLK in pull-down
•
PA13: JTMS/SWDAT in pull-up
•
PB4: NJTRST in pull-up
•
PB3: JTDO in floating state
When the pin is configured as output, the value written to the output data register
(GPIOx_ODR) is output on the I/O pin. It is possible to use the output driver in push-pull
mode or open-drain mode (only the N-MOS is activated when 0 is output).
The input data register (GPIOx_IDR) captures the data present on the I/O pin at every AHB1
clock cycle.
All GPIO pins have weak internal pull-up and pull-down resistors, which can be activated or
not depending on the value in the GPIOx_PUPDR register.
10
0
SPEED
[B:A]
0
0
AF
PP
0
0
1
AF
PP + PU
0
1
0
AF
PP + PD
0
1
1
Reserved
1
0
0
AF
OD
1
0
1
AF
OD + PU
1
1
0
AF
OD + PD
1
1
1
Reserved
00
x
x
x
0
0
Input
Floating
x
x
x
0
1
Input
PU
x
x
x
1
0
Input
PD
x
x
x
1
1
Reserved (input floating)
11
x
x
x
0
0
Input/output
Analog
x
x
x
0
1
Reserved
x
x
x
1
0
x
x
x
1
1
1. GP = general-purpose, PP = push-pull, PU = pull-up, PD = pull-down, OD = open-drain, AF = alternate
function.
Table 35. Port bit configuration table
(1)
(continued)
MODER(i)
[1:0]
OTYPER(i)
OSPEEDR(i)
[B:A]
PUPDR(i)
[1:0]
I/O configuration