ST72521 STMICROELECTRONICS [STMicroelectronics], ST72521 Datasheet - Page 49

• Manufacturer Part Number: ST72521
• Description: 8-BIT MCU WITH NESTED INTERRUPTS, FLASH, 10-BIT ADC, FIVE TIMERS, SPI, SCI, I2C, CAN INTERFACE
• Manufacturer: STMICROELECTRONICS [STMicroelectronics]

I/O PORTS (Cont’d)
Table 10. 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,
2. When the I/O port is in output configuration and the associated alternate function is enabled as an input,
reading the DR register will read the alternate function output status.
the alternate function reads the pin status given by the DR register content.
NOT IMPLEMENTED IN
TRUE OPEN DRAIN
I/O PORTS
NOT IMPLEMENTED IN
TRUE OPEN DRAIN
I/O PORTS
NOT IMPLEMENTED IN
TRUE OPEN DRAIN
I/O PORTS
PAD
PAD
PAD
V
V
V
DD
R
DD
DD
R
R
PU
PU
PU
PULL-UP
CONDITION
Hardware Configuration
INTERRUPT
CONDITION
ALTERNATE
ALTERNATE
REGISTER
ENABLE
ENABLE
DR
DR REGISTER ACCESS
EXTERNAL INTERRUPT
SOURCE (ei
REGISTER
REGISTER
DR
DR
DR REGISTER ACCESS
DR REGISTER ACCESS
W
R
x
)
ALTERNATE
ALTERNATE
OUTPUT
OUTPUT
ALTERNATE INPUT
ANALOG INPUT
R/W
R/W
DATA BUS
DATA BUS
DATA BUS
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