Function Of Int; I Interrupt Request Bit - Renesas 7700 FAMILY User Manual

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4.10.1 Function of INT

(1) Selecting edge sense mode
The interrupt request bit has the same function as that of internal interrupts. That is, when an
interrupt request occurs, the interrupt request bit is set to "1." The bit remains set to "1" until the
interrupt request is accepted; it is cleared to "0" when the interrupt request is accepted. By software,
this bit also can be set to "0" in order to clear the interrupt request or "1" in order to generate the
interrupt request.
(2) Selecting level sense mode
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The INT interrupt request bit becomes ignored.
i
In this case, the interrupt request occurs continuously while the level of the INT
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When the INT
i
request is accepted, this interrupt request is not retained. (Refer to Figure 4.10.4.)
1
Valid level : This means the level which is selected by the polarity select bit (bit 4 at addresses 7D
to 7F
2
Invalid level : This means the reversed level of a valid level.
INT pin
i
Fig. 4.10.3 Circuit of INT
interrupt request bit
i
pin level changes from the valid level to the invalid level
).
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Data bus
Edge detection
Interrupt request bit
circuit
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Interrupt
i
7751 Group User's Manual
4.10 External interrupts (INT
Level sense/Edge sense
select bit
"0"
"1"
INTERRUPTS
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interrupt)
i
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pin is valid level
i
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2 before the INT interrupt
i
Interrupt request
4–23
1 .
16