M38B53M4-059FP datasheet(279/355 Pages) MITSUBISHI

Part #	M38B53M4-059FP

Description	8-BIT SINGLE-CHIP MICROCOMPUTER

PDF	355 Pages

Scroll/Zoom	100%

Manufacturer	MITSUBISHI [Mitsubishi Electric Semiconductor]

Direct Link	http://www.mitsubishichips.com

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279 / 355 page

38B5 Group User’s Manual

3-31

APPENDIX

3.4 Countermeasures against noise

Fig. 3.4.10 Setup for I/O ports

3.4.5 Setup for I/O ports

Setup I/O ports using hardware and software as follows:

• Connect a resistor of 100

Ω or more to an I/O port in series.

• As for an input port, read data several times by a program for checking whether input levels are

equal or not.

• As for an output port, since the output data may reverse because of noise, rewrite data to its port

latch at fixed periods.

• Rewrite data to direction registers and pull-up control registers at fixed periods.

Note: When a direction register is set for input port again at fixed periods, a several-nanosecond short pulse

may be output from this port. If this is undesirable, connect a capacitor to this port to remove the noise

pulse.

Direction register

Port latch

Data bus

I/O port

pins

Noise

N.G.

O.K.

M38B53M4-059FP Datasheet(PDF) 279 Page - Mitsubishi Electric Semiconductor