Rohm LAPIS SEMICONDUCTOR ML620Q503, User Manual

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ML620Q503/Q504 User's Manual
Chapter 5 Interrupts
FEUL620Q504 5–55
A-2: When a subroutine is called by the program in executing an interrupt routine
A-2-1: When multiple interrupts are disabled
•Processing immediately after the start of interrupt routine execution
Specify the "PUSH LR" instruction to save the subroutine return address in the stack.
•Processing at the end of interrupt routine execution
Specify "POP LR" immediately before the RTI instruction to return from the interrupt processing
after returning the subroutine return address to LR.
A-2-2: When multiple interrupts are enabled
•Processing immediately after the start of interrupt routine execution
Specify "PUSH LR, ELR, EPSW" to save the interrupt return address, the subroutine return
address, and the EPSW status in the stack.
•Processing at the end of interrupt routine execution
Specify "POP PC, PSW, LR" instead of the RTI instruction to return the saved data of the interrupt
return address to PC, the saved data of EPSW to PSW, and the saved data of LR to LR.
Example of
description: Status
A-2-2
Intrpt_A-2-2: ; Start
PUSH
ELR,EPSW,LR
; Save ELR, EPSW, LR
at the beginning
EI ; Enable interrupt
: Sub_1: ;
: DI ; Disable interrupt
: :
:
BL Sub_1 ; Call subroutine Sub_1 :
: RT
; Return PC from
LR
POP PC, PSW, LR ; Return PC from the stack ; End of subroutine
; Return PSW from the
stack
; Return LR from the stack
; End