CHAPTER 13 INTERRUPT FUNCTIONS
163
(1)
Interrupt request flag registers 0 and 1 (IF0, IF1)
An interrupt request flag is set to 1, when the corresponding interrupt request is issued, or when the related
instruction is executed. It is cleared to 0, when the interrupt request is accepted, when a RESET signal is
input, or when a related instruction is executed.
IF0 and IF1 are set with a 1-bit or 8-bit memory manipulation instruction.
RESET input clears IF0 and IF1 to 00H.
Figure 13-2. Format of Interrupt Request Flag Register (
μ
PD789830)
Symbol
<7>
<6>
<5>
<4>
<3>
<2>
<1>
<0>
Address
After Reset
R/W
IF0
TMIF40
STIF00
SRIF00
SERIF00
PIF2
PIF1
PIF0
WDTIF
FFE0H
00H
R/W
7
6
<5>
<4>
<3>
<2>
<1>
<0>
IF1
0
0
KRIF00
WTIF
WTIIF
TMIF00
TMIF4
TMIF41
FFE1H
00H
R/W
××
IF
Interrupt Request Flag
0
No interrupt request signal has been issued.
1
An interrupt request signal has been issued; an interrupt request has been made.
Cautions 1. Bits 6 and 7 of IF1 must all be set to 0.
2. The WDTIF flag can be read- and write-accessed only when the watchdog timer is
being used as an interval timer. It must be cleared to 0 if the watchdog timer is used in
watchdog timer mode 1 or 2.
3. When port 2 is being used as an output port, and its output level is changed, an
interrupt request flag is set, because this port is also used as an external interrupt
input. To use port 2 in output mode, therefore, the interrupt mask flag must be set to 1
in advance.
Figure 13-3. Format of Interrupt Request Flag Register (
μ
PD78F9831)
Symbol
<7>
<6>
<5>
<4>
<3>
<2>
<1>
<0>
Address
After Reset
R/W
IF0
TMIF40
STIF00
SRIF00
SERIF00
PIF2
PIF1
PIF0
WDTIF
FFE0H
00H
R/W
<7>
<6>
<5>
<4>
<3>
<2>
<1>
<0>
IF1
PIF4
PIF3
KRIF00
WTIF
WTIIF
TMIF00
TMIF4
TMIF41
FFE1H
00H
R/W
××
IF
Interrupt Request Flag
0
No interrupt request signal has been issued.
1
An interrupt request signal has been issued; an interrupt request has been made.
Cautions 1. The WDTIF flag can be read- and write-accessed only when the watchdog timer is
being used as an interval timer. It must be cleared to 0 if the watchdog timer is used in
watchdog timer mode 1 or 2.
2. When ports 2 and 4 are being used as an output port, and its output level is changed,
an interrupt request flag is set, because this port is also used as an external interrupt
input. To use ports 2 and 4 in output mode, therefore, the interrupt mask flag must be
set to 1 in advance.