Port 4 - Fujitsu Semiconductor Controller MB89950/950A Hardware Manual

CHAPTER 4 I/O PORTS
4.6

Port 4

Port 4 is a general-purpose I/O port that also serves as the peripheral signal I/O pins.
Individual pin can be switched between the port and resource function. This section
principally describes the port functions when operating as a general-purpose I/O port.
The section describes the port structure and pins, the pin block diagram, and the port
registers for port 4.
I Structure of port 4
Port 4 consists of the following three components:
• General-purpose I/O port/peripheral I/O pins (P40 to P46/INT0)
• Port 4 data register (PDR4)
• Port 4 data direction register (DDR4)
I Port 4 pins
Port 4 consists of seven I/O pins of CMOS type input and output. Six of these pins are also used as I/O pins
for various peripherals. While they are being used by the peripheral, these pins cannot be used as the
general-purpose I/O port.
Table 4.6-1 "Port 4 pins" lists the port 4 pins.
Table 4.6-1 Port 4 pins
Port Pin name
P40
P41/PWM
P42/PWC/INT1
Port 4 P43/SI
P44/SO
P45/SCK
P46/INT0
See Section 1.7 "I/O Pins and Pin Functions" for a description of the circuit type.
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Function
P40 general-purpose I/O port
P41 general-purpose I/O port PWM (PWM output)
P42 general-purpose I/O port PWC/INT1 (PWC or external interrupt input)
P43 general-purpose I/O port SI (UART/8-bit SIO serial data input)
P44 general-purpose I/O port SO (UART/8-bit SIO serial data output)
P45 general-purpose I/O port SCK (UART/8-bit SIO serial clock I/O)
P46 general-purpose I/O port INT0 (External interrupt input)
Shared peripheral
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I/O type
Circuit
type
Input Output
CMOS CMOS E