NEC mPD789026 Subseries, User Manual

Page: 153 / 213

CHAPTER 10 INTERRUPT FUNCTIONS
User's Manual U11919EJ3V0UM00
153
(1) Interrupt request flag registers (IF0 and IF1)
The interrupt request flag is set to 1 when the corresponding interrupt request is generated or an instruction
is executed. It is cleared to 0 upon acknowledgement of an interrupt request, upon RESET input, or when
an 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 10-2. Interrupt Request Flag Register Format
Cautions 1. Be sure to clear bit 7 of IF0 and bits 1 to 6 of IF1 to 0.
2. TMIF4 flag is R/W enabled only when a watchdog timer is used as an interval timer. If
the watchdog timer mode 1 or 2 is used, set TMIF4 flag to 0.
3. Because port 3 has an alternate function as the external interrupt input, when the
output level is changed by specifying the output mode of the port function, an
interrupt request flag is set. Therefore, 1 should be set in the interrupt mask flag
before using the output mode.
0
1
0 TMIF00 STIF00 SRIF00 PIF2 PIF1 PIF0 TMIF4 IF0
R/W
FFE0H 00H R/W
Symbol
Address After Reset
Interrupt Request Flag
No interrupt request signal is generated
Interrupt request signal is generated; Interrupt request state
××
IF
×
<6> <5> <4> <3> <2> <1> 7 <0>
TMIF20 0 0 0 0 0 0 KRIF00 IF1 FFE1H 00H R/W
6 5 4 3 2 1 <7> <0>