Noise - Renesas M16C FAMILY Hardware Manual

Under development
Preliminary specification
Specifications in this manual are tentative and subject to change.
R8C/11 Group

19.7 Noise

(1) Bypass Capacitor between V
Insert a bypass capacitor (at least 0.1 µF) between V
sures 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 exter-
nal 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 rou-
tine 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 )
between CNVss and Vss, and placed as close as possible to the CNVss pin.
Rev.0.91 2003 Sep 08
and V
CC
page 178 of 184
Pins
SS
and V
CC
19. Usage Notes
pins as the countermea-
SS