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CHAPTER 4 I/O PORTS
4.1 Overview of I/O Ports
Six I/O ports (comprising 26 pins) are available as general-purpose I/O ports (parallel I/O
ports).
These ports also serve peripherals (as I/O pins for specific peripheral functions).
■ Functions of I/O Ports
The I/O ports function to output data from the CPU to I/O pins via their port data register (PDR) and send
signals input to I/O pins to the CPU. For some ports, the I/O direction of I/O pins can be set by optionally
setting the bits of the port data direction register (DDR), with the bits corresponding to the pins.
The functions of the ports and peripherals for which the ports may serve are summarized below.
• Port 0:General-purpose I/O port may also serve peripherals (external interrupt 2 and analog input pins)
• Port 3:General-purpose I/O port may also serve peripherals (12-bit PPG, external interrupt 1, UART, 8-
bit serial I/O, 8/16-bit timers, and buzzer output pin)
• Port 4:General-purpose I/O port of a type switched between CMOS push-pull and N-ch open-drain may
also serve peripherals (analog input pins)
• Port 5:General-purpose I/O port may also serve peripherals (8-bit PWM pin)
• Port 6:General-purpose I/O port (for MB89F202/F202RA, P61, P60 are input port)
• Port 7:General-purpose I/O port
Table 4.1-1 lists the functions of the ports, and Table 4.1-2 lists the register of ports.
Table 4.1-1 Functions of Ports
Port
name
Pin name
Input
form
Output
form
bit7 bit6 bit5 bit4 bit3 bit2 bit1 bit0
Port 0
P00/INT20
/
AN4 to
P07/INT27
Hysteresis
CMOS
analog
CMOS
push-pull
P07 P06 P05 P04 P03 P02 P01 P00
INT27
INT26 INT25 INT24
AN7 AN6 AN5 AN4
INT23 INT22 INT21 INT20
Port 3
P30/UCK/SCK
to
P37/BZ/PPG
CMOS
hysteresis
P37 P36 P35 P34 P33 P32 P31 P30
BZ/
PPG
INT12 INT11
TO/
INT10
EC UI/SI UO/SO
UCK/
SCK
Port 4
P40/AN0
to
P43/AN3
CMOS
analog
CMOS
push-pull
or N-ch
open-drain
----
P43 P42 P41 P40
AN3 AN2 AN1 AN0
Port 5 P50/PWM
CMOS
hysteresis
CMOS
push-pull
------ -
P50
PWM
Port 6
P60,
P61
CMOS
hysteresis
CMOS
push-pull
or N-ch
open-drain
------
P61 P60
--
Port 7 P70
to
P72
CMOS CMOS - - - - - P72 P71 P70