
Under
development
Tentative Specifications REV.E
Specifications in this manual are tentative and subject to change.
Mitsubishi microcomputers
M30100/M30102 Group
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
Usage precaution
130
Example 2:
INT_SWITCH2:
FCLR
I
; Disable interrupts.
AND.B
#00h, 0055h
; Clear T1IC int. priority level and int. request bit.
MOV.W
MEM, R0
; Dummy read.
FSET
I
; Enable interrupts.
Example 3:
INT_SWITCH3:
PUSHC
FLG
; Push Flag register onto stack
FCLR
I
; Disable interrupts.
AND.B
#00h, 0055h
; Clear T1IC int. priority level and int. request bit.
POPC
FLG
; Enable interrupts.
Note: The reason why two NOP instructions or dummy read were inserted before the FSET I for ex. 1 &
2 is to prevent interrupt enable flag from being set, due to the effects of instruction queue, before
the rewritten value of the interrupt control register takes effect.
When an instruction to rewrite the interrupt control register is executed while the interrupt is disabled,
depending on the instruction used for rewriting, there are times the interrupt request bit is not set even if
an interrupt request for that register has been generated. If this creates a problem, please use any of the
instructions below to rewrite the register.
Instructions : AND, OR, BCLR, BSET
Changing the interrupt request bit
When attempting to clear the interrupt request bit of an interrupt control register, the interrupt request bit
is not cleared sometimes. This will depend on the instruction. If this creates problems, use the below
instructions to change the register.
Instructions : MOV
Noise
(1) Bypass Capacitor between VCC and VSS Pins
Insert a bypass capacitor (at least 0.1
F) between VCC and VSS pins as noise and latch-up counter-
measures. In addition, make sure that connecting lines are 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 peri-
odically re-set the port registers, port direction registers and pull-up control registers. However, you
should fully examine before introducing the re-set routine as conflicts may be created between this re-
set 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.