4518 Datasheet, PDF (95/160 Pages) Renesas Technology Corp – SINGLE-CHIP 4-BIT CMOS MICROCOMPUTER

4518 Group
MACHINE INSTRUCTIONS (INDEX BY ALPHABET) (continued)
DEY (DEcrement register Y)
Instruction
code
D9
D0
Number of Number of Flag CY
words
cycles
0
0
0
0
0
1
0
1
1
1
2
0
1
7 ₁₆
1
1
–
Skip condition
(Y) = 15
Operation: (Y) ← (Y) – 1
Grouping: RAM addresses
Description: Subtracts 1 from the contents of register Y.
As a result of subtraction, when the con-
tents of register Y is 15, the next instruction
is skipped. When the contents of register Y
is not 15, the next instruction is executed.
DI (Disable Interrupt)
Instruction
code
D9
D0
Number of Number of Flag CY
0000000100
004
words
cycles
2
16
1
1
–
Skip condition
–
Operation: (INTE) ← 0
Grouping: Interrupt control operation
Description: Clears (0) to interrupt enable flag INTE, and
disables the interrupt.
Note:
Interrupt is disabled by executing the DI in-
struction after executing 1 machine cycle.
DWDT (Disable WatchDog Timer)
Instruction
code
D9
D0
Number of Number of Flag CY
1010011100
29C
words
cycles
2
16
1
1
–
Skip condition
–
Operation: Stop of watchdog timer function enabled
Grouping: Other operation
Description: Stops the watchdog timer function by the
WRST instruction after executing the
DWDT instruction.
EI (Enable Interrupt)
Instruction
code
D9
D0
Number of Number of Flag CY
0000000101
005
words
cycles
2
16
1
1
–
Skip condition
–
Operation: (INTE) ← 1
Grouping: Interrupt control operation
Description: Sets (1) to interrupt enable flag INTE, and
enables the interrupt.
Note:
Interrupt is enabled by executing the EI in-
struction after executing 1 machine cycle.
Rev.3.01 2005.06.15 page 95 of 157
REJ03B0008-0301