
ST72321xx-Auto I/O ports
Doc ID 13829 Rev 1 73/243
Table 30. I/O port configurations
Hardware configuration
Input
(1)
Open-drain output
(2)
Push-pull output
(2)
1. When the I/O port is in input configuration and the associated alternate function is enabled as an output, reading the DR
register will read the alternate function output status.
2. When the I/O port is in output configuration and the associated alternate function is enabled as an input, the alternate
function reads the pin status given by the DR register content.
CONDITION
PAD
V
DD
R
PU
EXTERNAL INTERRUPT
DATA BUS
PULL-UP
INTERRUPT
DR REGISTER ACCESS
W
R
SOURCE (ei
x
)
DR
REGISTER
CONDITION
ALTERNATE INPUT
NOT IMPLEMENTED IN
TRUE OPEN DRAIN
I/O PORTS
ANALOG INPUT
PA D
R
PU
DATA BUS
DR
DR REGISTER ACCESS
R/W
V
DD
ALTERNATEALTERNATE
ENABLE OUTPUT
REGISTER
NOT IMPLEMENTED IN
TRUE OPEN DRAIN
I/O PORTS
PA D
R
PU
DATA BUS
DR
DR REGISTER ACCESS
R/W
V
DD
ALTERNATEALTERNATE
ENABLE OUTPUT
REGISTER
NOT IMPLEMENTED IN
TRUE OPEN DRAIN
I/O PORTS
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