Figure 12.5A External Interrupt Circuit Settings; Figure 12.5B External Interrupt (Int1) Operation; Operation Of External Interrupt Circuit - Fujitsu F2MC-8L MB89620 Series Hardware Manual

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Operation of External Interrupt Circuit

The external interrupt circuit can detect a specified edge on a signal input to an
external interrupt pin.
n Operation of External Interrupt Circuit
Figure 12.5a shows the settings required to operate the external interrupt circuit.
If the edge polarity on the input signal from the external interrupt pins (INT0 to INT3) matches
the edge polarity selected by the external interrupt control register (EIC1, EIC2: SEL0 to SEL3),
the corresponding external interrupt request flag bit (EIC1, EIC2: EIR0 to EIR3) is set to "1".
The external interrupt request flag bit is set when the edge polarity match occurs, regardless of
the value of the interrupt request enable bit (EIC1, EIC2: EIE0 to EIE3).
Figure 12.5b shows the operation when an external interrupt is input to the INT1 pin.
Input waveform
to the INT1 pin
EIR1 bit
EIE1 bit
SEL1 bit
IRQ1
Note: The pin state can be read directly from the port data register (PDR6), even when used as an
external interrupt input.
MB89620 series
Bit 7 Bit 6 Bit 5
EIC1 EIR1 — SEL1
EIC2 EIR3 — SEL3

Figure 12.5a External Interrupt Circuit Settings

Cleared at the same time
as the EIE1 bit is set.
Rising edge set

Figure 12.5b External Interrupt (INT1) Operation

CHAPTER 12 EXTERNAL INTERRUPT CIRCUIT (EDGE)
Bit 4 Bit 3 Bit 2
EIE1 EIR0 —
EIE3 EIR2 —
Interrupt request flag bit
cleared by the program.
Falling edge set
Bit 1 Bit 0
SEL0 EIE0
SEL2 EIE2
: Used bit
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