Datasheet

RL78/L12 CHAPTER 17 INTERRUPT FUNCTIONS
R01UH0330EJ0200 Rev.2.00 715
Dec 13, 2013
17.3.5 Program status word (PSW)
The program status word is a register used to hold the instruction execution result and the current status for an interrupt
request. The IE flag that sets maskable interrupt enable/disable and the ISP0 and ISP1 flags that controls multiple
interrupt servicing are mapped to the PSW.
Besides 8-bit read/write, this register can carry out operations using bit manipulation instructions and dedicated
instructions (EI and DI). When a vectored interrupt request is acknowledged, if the BRK instruction is executed, the
contents of the PSW are automatically saved into a stack and the IE flag is reset to 0. Upon acknowledgment of a
maskable interrupt request, if the value of the priority specification flag register of the acknowledged interrupt is not 00, its
value minus 1 is transferred to the ISP0 and ISP1 flags. The PSW contents are also saved into the stack with the PUSH
PSW instruction. They are restored from the stack with the RETI, RETB, and POP PSW instructions.
Reset signal generation sets PSW to 06H.
Figure 17-6. Configuration of Program Status Word
<7>
IE
<6>
Z
<5>
RBS1
<4>
AC
<3>
RBS0
<2>
ISP1
<1>
ISP0
0
CYPSW
After reset
06H
ISP1
0
0
1
1
Enables interrupt of level 0
(while interrupt of level 1 or 0 is being serviced).
Enables interrupt of level 0 and 1
(while interrupt of level 2 is being serviced).
Enables interrupt of level 0 to 2
(while interrupt of level 3 is being serviced).
Enables all interrupts
(waits for acknowledgment of an interrupt).
IE
0
1
Disabled
Enabled
Priority of interrupt currently being serviced
Interrupt request acknowledgment enable/disable
Used when normal instruction is executed
ISP0
0
1
0
1
<R>