NEC uPD78056Y - Manual (Page 506)

506
CHAPTER 21 INTERRUPT AND TEST FUNCTIONS
21.4.5 Interrupt request reserve
In some cases, the acknowledgment of the interrupt request is reserved even an interrupt request is generated
during processing of the instruction until the execution of the next instruction is completed. The following shows this
type of instructions (interrupt request reserve instruction).
• MOV PSW, #byte
• MOV A, PSW
• MOV PSW, A
• MOV1 PSW.bit, CY
• MOV1 CY, PSW.bit
• AND1 CY, PSW.bit
• OR1 CY, PSW.bit
• XOR1 CY, PSW.bit
• SET1 PSW.bit
• CLR1 PSW.bit
• RETB
• RETI
• PUSH PSW
• POP PSW
• BT PSW.bit, $addr16
• BF PSW.bit, $addr16
• BTCLR PSW.bit, $addr16
• EI
• DI
• Manipulate instructions for IF0L, IF0H, IF1L, MK0L, MK0H, MK1L, PR0L, PR0H, PR1L, INTM0, INTM1 registers
Caution The BRK instruction is not an interrupt request reserve instruction shown above. However, in
the case of software interrupt that is started up with the execution of the BRK instruction, the
IE flag is cleared to 0. Therefore, interrupts are not acknowledged even when a maskable
interrupt request is issued during the execution of the BRK instruction. However, non-maskable
interrupt requests are acknowledged.
Figure 21-17 shows the timing when an interrupt request is reserved.
Figure 21-17. Interrupt Request Hold
Remarks 1. Instruction N: Instruction that holds interrupts requests
2. Instruction M: Instructions other than instruction N
3. The
××
PR (priority level) values do not affect the operation of
××
IF (interrupt request).
CPU processing
Ч Ч IF
Instruction N Instruction M
Save PSW and PC,
Jump to interrupt service Interrupt service
program