ST72104G, ST72215G, ST72216G, ST72254G
I/O PORTS (Cont’d)
Table 7. I/O Port Configurations
Hardware Configuration
DR REGISTER ACCESS
NOT IMPLEMENTED IN
TRUE OPEN DRAIN
I/O PORTS
V
DD
R
PULL-UP
CONFIGURATION
W
R
PU
DR
REGISTER
DATA BUS
PAD
ALTERNATE INPUT
FROM
OTHER
PINS
EXTERNAL INTERRUPT
SOURCE (ei )
x
INTERRUPT
POLARITY
CONFIGURATION
SELECTION
ANALOG INPUT
NOT IMPLEMENTED IN
TRUE OPEN DRAIN
I/O PORTS
DR REGISTER ACCESS
V
DD
R
PU
R/W
DR
REGISTER
DATA BUS
PAD
ALTERNATE
ENABLE
ALTERNATE
OUTPUT
NOT IMPLEMENTED IN
TRUE OPEN DRAIN
I/O PORTS
DR REGISTER ACCESS
V
DD
R
PU
R/W
DR
REGISTER
DATA BUS
PAD
ALTERNATE
ENABLE
ALTERNATE
OUTPUT
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.
32/140
ETC [ ETC ]
