Datasheet
78K0/Ix2 CHAPTER 18 INTERRUPT FUNCTIONS
R01UH0010EJ0500 Rev.5.00 599
Feb 28, 2012
18.4.4 Interrupt request hold
There are instructions where, even if an interrupt request is issued for them while another instruction is being executed,
request acknowledgment is held pending until the end of execution of the next instruction. These instructions (interrupt
request hold instructions) are listed below.
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
Manipulation instructions for the IF0L, IF0H, IF1L, IF1H, MK0L, MK0H, MK1L, MK1H, PR0L, PR0H, PR1L, and
PR1H registers.
Caution The BRK instruction is not one of the above-listed interrupt request hold instructions. However, the
software interrupt activated by executing the BRK instruction causes the IE flag to be cleared.
Therefore, even if a maskable interrupt request is generated during execution of the BRK instruction,
the interrupt request is not acknowledged.
Figure 18-18 shows the timing at which interrupt requests are held pending.
Figure 18-18. Interrupt Request Hold
Instruction N Instruction M
PSW and PC saved, jump
to interrupt servicing
Interrupt servicing
program
CPU processing
××IF
Remarks 1. Instruction N: Interrupt request hold instruction
2. Instruction M: Instruction other than interrupt request hold instruction
3. The PR (priority level) values do not affect the operation of IF (interrupt request).