Datasheet

ST72321Rx ST72321ARx ST72321Jx
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I/O PORTS (Cont’d)
Table 11. I/O Port Configurations
Notes:
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.
Hardware Configuration
INPUT
1)
OPEN-DRAIN OUTPUT
2)
PUSH-PULL OUTPUT
2)
CONDITION
PAD
V
DD
R
PU
EXTERNAL INTERRUPT
DATA B US
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
PAD
R
PU
DATA B US
DR
DR REGISTER ACCESS
R/W
V
DD
ALTERNATEALTERNATE
ENABLE OUTPUT
REGISTER
NOT IMPLEMENTED IN
TRUE OPEN DRAIN
I/O PORTS
PAD
R
PU
DATA B US
DR
DR REGISTER ACCESS
R/W
V
DD
ALTERNATEALTERNATE
ENABLE OUTPUT
REGISTER
NOT IMPLEMENTED IN
TRUE OPEN DRAIN
I/O PORTS