R8C datasheet(183/199 Pages) RENESAS

Il numero della parte	R8C

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R8C/10 Group

19. Usage Notes

Rev.1.20 Jan 27, 2006

page 173 of 180

REJ09B0019-0120

19.8 Noise

(1) Bypass Capacitor between VCC and VSS Pins

Insert a bypass capacitor (at least 0.1 µF) between VCC and VSS pins as the countermeasures against

noise and latch-up. The connecting wires must be the shortest and widest possible.

(2) Port Control Registers Data Read Error

During severe noise testing, mainly power supply system noise, and introduction of external noise, the

data of port related registers may changed. As a firmware countermeasure, it is recommended to

periodically reset the port registers, port direction registers and pull-up control registers. However, you

should fully examine before introducing the reset routine as conflicts may be created between this

reset routine and interrupt routines (i. e. ports are switched during interrupts).

(3) CNVss Pin Wiring

In order to improve the pin tolerance to noise, insert a pull down resistance (about 5 k

Ω) between

CNVss and Vss, and placed as close as possible to the CNVss pin.

R8C Scheda tecnica(PDF) 183 Page - Renesas Technology Corp