7702 datasheet(24/217 Pages) RENESAS

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DESCRIPTION

7702/7703 Group User’s Manual

1–10

1.3 Pin description

(2)

In memory expansion mode

Table 1.3.5 Example for processing unused pins in memory expansion mode

Pin name

Ports P42 to P47, P5 to P8

____

BHE (Note 2)

ALE (Note 3)

_____

HLDA (Note 6)

XOUT (Note 5)

_____

____

HOLD, RDY (Note 8)

AVcc

AVss, VREF

Example of processing

Set for input mode and connect these pins to Vcc or

Vss via a resistor; or set for output mode and leave

these pins open. (Notes 1, 6, 7)

Leave them open. (Note 4)

Leave it open.

Connect these pins to Vcc via a resistor (pull-up).

Connect this pin to Vcc.

Connect these pins to Vss.

Notes 1: When setting these ports to the output mode and leave them open, they remain set to the input

mode until they are switched to the output mode by software after reset. While ports remain set

to the input mode, consequently, voltage levels of pins are unstable, and a power source current can increase.

The contents of the direction register can be changed by noise or a program runaway generated

by noise. To improve its reliability, we recommend to periodically set the contents of the direction

When processing unused pins, use the possible shortest wiring (within 20 mm from the microcomputer).

2: This applies when “H” level is input to the BYTE pin.

3: This applies when “H” level is input to the BYTE pin and the access space is 64 Kbytes.

4: When supplying Vss level to the CNVss pin, these pins remain set to the input mode until they

are switched to the output mode by software after reset. While pins remain set to the input mode,

consequently, voltage levels of pins are unstable, and a power source current can increase.

5: This applies when a clock externally generated is input to the XIN pin.

6: In the 7703 Group, the following ports does not have the corresponding pins and have only the

direction registers. Fix the bit of these direction registers to “1” (output mode).

•Ports P43–P46, P60, P61, P66, P67, P73–P76, P84, P85

_____

There is not the HLDA pin.

7: Set the P42/

φ1 pin to the P42 function (clock φ1 output disabled), and perform the same processing

as ports P43–P47, P5–P8.

8: When processing unused pins, use the possible shortest wiring (within 20 mm from the microcomputer).

P42–P47, P5–P8

AVSS

VREF

HOLD

RDY

VCC

VSS

AVCC

XOUT

BHE

ALE

HLDA

P42–P47, P5–P8

AVSS

VREF

HOLD

RDY

VSS

AVCC

XOUT

BHE

ALE

HLDA

VCC

Left open

q When setting ports for input mode

q When setting ports for output mode

Left open

Fig. 1.3.2 Example for processing unused pins in memory expansion mode

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