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CHAPTER 11 EXTERNAL INTERRUPT CIRCUIT 2 (LEVEL)
11.4.2 External Interrupt 2 Flag Register (EIF2)
The external interrupt 2 flag register (EIF2) is used to hold the interrupt state by flagging
an interrupt request flag when a level interrupt is detected and then clearing the flag.
■ External Interrupt 2 Flag Register (EIF2)
Figure 11.4-3 External Interrupt 2 Flag Register (EIF2)
IF20
0
1
bit7 bit6 bit5 bit4 bit3 bit2 bit1 bit0
0037
H IF20 -------0B
R/W
R/W
Address
Initial value
External interrupt request flag bit
When being read
When being written
No interrupt request
("L" level not detected)
This bit is cleared
Interrupt request is generated
("L" level detected)
No change in the bit, does not
affect other operations
:
Readable/Writable
: Unused
: Initial value
Table 11.4-3 Explanation of Functions of Each Bit in External Interrupt 2 Flag Register
(EIF2)
Bit name Function
bit7
to
bit1
Unused bits
• Bit value is undefined when being read.
• The written value does not affect other operations.
bit0
IF20:
External interrupt
request flag bit
• When an "L" level signal is input to one of the external
interrupt pins(INT20
to INT27) for which external
interrupt inputs are enabled, this bit is set to "1".
• Writing "0" clears this bit, and writing "1" does not change
this bit state and does not affect other operations.
Note:
The external interrupt enable bits of the external interrupt 2
control register (EIE2:IE20 to IE27) may disable external
interrupt inputs. Interrupt requests continue to be generated
and issued to the CPU until the IF20 bit is cleared to "0".