Notes On Noise; Inserting A Bypass Capacitor Between Vcc And Vss Pins As A Countermeasure Against Noise And Latch-Up; Countermeasures Against Noise Error Of Port Control Registers - Renesas R8C/18 Series Hardware Manual

R8C/18 Group, R8C/19 Group
19.7

Notes on Noise

19.7.1 Inserting a Bypass Capacitor between VCC and VSS Pins as a
Countermeasure against Noise and Latch-Up
Connect a bypass capacitor (at least 0.1 µ F) using the shortest and thickest wire possible.
19.7.2

Countermeasures against Noise Error of Port Control Registers

During rigorous noise testing or the like, external noise (mainly power supply system noise) can
exceed the capacity of the MCU's internal noise control circuitry. In such cases the contents of the
port related registers may be changed.
As a firmware countermeasure, it is recommended that the port registers, port direction registers, and
pull-up control registers be reset periodically. However, examine the control processing fully before
introducing the reset routine as conflicts may be created between the reset routine and interrupt
routines.
Rev.1.30 Apr 14, 2006
REJ09B0222-0130
Page 227 of 233
19. Usage Notes