M16C80 Datasheet, PDF (231/358 Pages) Renesas Technology Corp – RENESAS 16-BIT SINGLE-CHIP MICROCOMPUTER M16C FAMILY / M16C/80 SERIES

M16C/80 Group
27. Usage Precaution
Noise
(1) A bypass capacitor should be inserted between Vcc-Vss line for reducing noise and latch-up
Connect a bypass capacitor (approx. 0.1µF) between the Vcc and Vss pins using short wiring and
thicker circuit traces.
Precautions for using CLKOUT pin
When using the Clock Output function of P53/CLKOUT pin (f8, f32 or fc output) in single chip mode, use
port P57 as an input only port (port P57 direction register is "0").
Although port P57 may be set as an output port, it will become high impedance and will not output "H" or
"L" levels.
__________
HOLD signal
When P40 to P47 and P50 to P52 are set to output port (the direction register is "1") in single-chip
mode, then the MCU is changed to microprocessor mode or memory expansion mode.
__________
_______ _______
_______
Although the HOLD pin may be held "L", P40 to P47 (A16 to A23, CS0 to CS3, MA8 to MA12)
_____ _____ _______ _____ _______ _______ _________ _________ _____
and P50 to P52 (RD/WR/BHE, RD/WRL/WRH, CASL/CASH/DW) will not become high-impedance
ports.
__________
When using the HOLD input while P40 to P47 and P50 to P52 are set as output ports in single-chip mode,
you must first set all pins for P40 to P47 and P50 to P52 as input ports, then shift to microprocessor mode
or memory expansion mode.
Rev.1.00 Aug. 02, 2005 ^{Page 220} of 329
REJ09B0187-0100