M30620FCAFP datasheet(182/615 Pages) RENESAS

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Mitsubishi microcomputers

M16C / 62A Group

SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER

Programmable I/O Port

1-163

Programmable I/O Ports

There are 87 programmable I/O ports: P0 to P10 (excluding P85). 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. P85 is

an input-only port and has no built-in pull-up resistance.

Figures 1.20.1 to 1.20.4 show the programmable I/O ports. Figure 1.20.5 shows the I/O pins.

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 1.20.6 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.

In memory expansion and microprocessor mode, the contents of corresponding direction register of pins

_______

_____

________ ______

________ _______

_______

__________

_________

A0 to A19, D0 to D15, CS0 to CS3, RD, WRL/WR, WRH/BHE, ALE, RDY, HOLD, HLDA and BCLK cannot

be modified.

Note: There is no direction register bit for P85.

(2) Port registers

Figure 1.20.7 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.

In memory expansion and microprocessor mode, the contents of corresponding port register of pins A0 to

_______

________

_____

________ ______

________ ________

_______

__________

_________

A19, D0 to D15, CS0 to CS3, RD, WRL/WR, WRH/BHE, ALE, RDY, HOLD, HLDA and BCLK cannot be

modified.

(3) Pull-up control registers

Figure 1.20.8 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.

However, in memory expansion mode and microprocessor mode, the pull-up control register of P0 to P3,

P40 to P43, and P5 is invalid. The contents of register can be changed, but the pull-up resistance is not

connected.

(4) Port control register

Figure 1.20.9 shows the port control register.

The bit 0 of port control register is used to read port P1 as follows:

0 : When port P1 is input port, port input level is read.

When port P1 is output port , the contents of port P1 register is read.

1 : The contents of port P1 register is read always.

This register is valid in the following:

• External bus width is 8 bits in microprocessor mode or memory expansion mode.

• Port P1 can be used as a port in multiplexed bus for the entire space.

M30620FCAFP Datasheet(PDF) 182 Page - Renesas Technology Corp

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