uPD789871 Subseries 8-Bit Single-Chip Microcontrollers PUM
uPD789871 Subseries 8-Bit Single-Chip Microcontrollers PUM
uPD789871 Subseries 8-Bit Single-Chip Microcontrollers PUM
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124<br />
CHAPTER 12 INTERRUPT FUNCTIONS<br />
(1) Interrupt request flag registers (IF0, IF1)<br />
The interrupt request flag is set to 1 when the corresponding interrupt request is generated or an instruction<br />
is executed. It is cleared to 0 when an instruction is executed upon acknowledgement of an interrupt request<br />
or upon RESET input.<br />
IF0 and IF1 are set with a 1-bit or 8-bit memory manipulation instruction.<br />
RESET input clears these registers to 00H.<br />
0<br />
1<br />
Figure 12-2. Interrupt Request Flag Register Format<br />
Symbol Address After reset R/W<br />
IF0 CSIIF10 KSIF TMIF52 TMIF51 TMIF50 PIF1 PIF0 WDTIF FFE0H 00H R/W<br />
Symbol 7 6 5 4 <br />
Address After reset<br />
IF1<br />
0 0 0 0 WTIIF WTIF TMIF81 TMIF80<br />
××IF×<br />
No interrupt request signal is generated<br />
Interrupt request flag<br />
Interrupt request signal is generated; Interrupt request state<br />
Cautions 1. WDTIF flag is R/W enabled only when the watchdog timer is used as an interval timer.<br />
If the watchdog timer mode 1 and 2 are used, set the WDTIF flag to 0.<br />
2. Because port 2 has an alternate function as the external interrupt input, when the output<br />
level is changed by specifying the output mode of the port function, an interrupt request<br />
flag is set. Therefore, the interrupt mask flag should be set to 1 before using the output<br />
mode.<br />
Preliminary User’s Manual U14938EJ1V0UM<br />
R/W<br />
FFE1H 00H R/W
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