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<Sample program>
(Initialization)
MOV
MOV
MOV
MOV
EI
EI
EI
(Main routine)
SKT
HALT
NOP
SKTCLR
BR
CALL
MAIN:
.
.
.
.
.
.
.
.
.
.
(INT4 service routine)
VINT4:
SKT
BR
CLR1
MOV
MOV
WAIT1:
SKT
BR
SKT
BR
CLR1
RETI
PDOWN:
SET1
MOV
WAIT2:
INCS
BR
SET1
RETI
Caution Before the system clock is changed from the main system clock to the subsystem clock,
a wait time sufficient for stable subsystem clock generation is required.
A,#0011B
PCC,A
; High-speed mode
XA,#05
WM,XA
; Subsystem clock
IE4
IEW
; Enable interrupt
PORT0.0
; Power normal?
; Power-down mode
; Power normal?
IRQW
; Flag set for 0.5 second?
MAIN
; NO
WATCH
; Clock subroutine
PORT0.0
; Power normal? MBE = 0
PDOWN
SCC.3
; Start main system clock oscillation
A,#8
BTM,A
IRQBT
; Wait for 250 ms
WAIT1
PORT0.0
; Chattering check
PDOWN
SCC.0
; Switch to main system clock
SCC.0
; Switch to subsystem clock
A,#6
A
; Wait for 32 machine cycles
WAIT2
SCC.3
; Stop main system clock oscillation
CHAPTER 7 STANDBY FUNCTION
223
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