M30218 Datasheet, PDF (129/179 Pages) Mitsubishi Electric Semiconductor – M30218 Group

Programmable I/O Ports
Mitsubishi microcomputers
M30218 Group
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
Programmable I/O Ports
There are 48 programmable I/O ports: P3, P4 and P7 to P10. Each port can be set independently for input
or output using the direction register. A pull-up resistance for each block of 4 ports can be set.
P3 and P40 to P43 are high-breakdown-voltage, P-channel open drain outputs, and have no built-in pull-
down resistance.
Figures UA-1, UA-2 show the programmable I/O ports.
Each pin functions as a programmable I/O port and as the I/O for the built-in peripheral devices.
To use the pins as the inputs for the built-in peripheral devices, set the direction register of each pin to input
mode. When the pins are used as the outputs for the built-in peripheral devices (other than the D-A con-
verter), they function as outputs regardless of the contents of the direction registers. When pins are to be
used as the outputs for the D-A converter, do not set the direction registers to output mode. See the
descriptions of the respective functions for how to set up the built-in peripheral devices.
(1) Direction registers
Figure UA-3 shows the direction registers.
These registers are used to choose the direction of the programmable I/O ports. Each bit in these regis-
ters corresponds one for one to each I/O pin.
(2) Port registers
Figure UA-4 shows the port registers.
These registers are used to write and read data for input and output to and from an external device. A
port register consists of a port latch to hold output data and a circuit to read the status of a pin. Each bit
in port registers corresponds one for one to each I/O pin.
(3) Pull-up control registers
Figure UA-5 shows the pull-up control registers.
The pull-up control register can be set to apply a pull-up resistance to each block of 4 ports. When ports
are set to have a pull-up resistance, the pull-up resistance is connected only when the direction register is
set for input.
Note: P3, P40 to P43 have no built-in pull-up resistance, because of these pin's are high-breakdown-
voltage, P-channel open drain outputs.
Exclusive High-breakdown-voltage Output Ports
There are 40 exclusive output Ports: P0 to P2, P5 and P6.
All ports have structure of high-breakdown-voltage P-channel open drain output. Exclusive output ports
except P2 have built-in pull-down resistance.
Figure UA-1 shows the configuration of the exclusive high-breakdown-voltage output ports.
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