128
µ
PD17062
MAIN A
MAIN
B
A
CBAMAIN
BAAA
RETIRETI
RET
AAAA
BANK0
CLR1 IXE
DI
BANK0
CLR1 IXE
EI
Undefined
Undefined
Main routine Interrupt A Interrupt B Interrupt C
Undefined
Fig. 11-8 Example of Using Multiple Level-3 Interrupts
To interrupt A, be sure to set a lower priority than interrupts B and C. Fix the bank register and index enable
flag (BANK0 and IXE = 0 in this example) in the main routine that permits interrupt A. This processing enables
the use of RET instructions for multiple interrupts of three levels after specifying the bank register and index
enable flag of the main routine.
If the bank register and index enable flag at interrupt A are exactly the same as those of the main routine,
the RETI instruction can be used. However, because the operation of the 17K series emulator differs as shown
in Fig. 11-9, the RETI instruction cannot be used for debugging.