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CHAPTER 11 EXTERNAL INTERRUPT CIRCUIT (EDGE)
11.5
Operation of the External Interrupt Circuit
The external interrupt circuit can detect a specified edge on a signal input to an external
interrupt pin.
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Operation of the external interrupt circuit
Figure 11.5-1 "External interrupt circuit settings" shows the settings required to operate the external
interrupt circuit.
Figure 11.5-1 External interrupt circuit settings
If the polarity of an edge on the input signal to one of the external interrupt pins (INT0 - INT1) matches the
edge polarity specified for the pin in the external interrupt control register (EIC: SL11, SL10, SL01, SL00),
the external interrupt circuit sets the external interrupt request flag bit (EIC: EIR0 - EIR1) 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 (EIC: EIE0 - EIE1).
Figure 11.5-2 "External interrupt (INT1) operation" shows the operation when an external interrupt is input
to the INT1 pin.
Figure 11.5-2 External interrupt (INT1) operation
Reference:
The pin state can be read directly from the port data register (PDR4), even when used as an external
interrupt input.
EIC1
EIR1
SL11 SL10
EIE1
EIR0
SL01 SL00
EIE0
: Used bit
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Input waveform
to the INT1 pin
Cleared at the same time
as the EIE1 bit is set.
Interrupt request flag bit is cleared
by the program.
EIR1 bit
EIE1 bit
SL11 bit
Rising edge set
Falling edge set
IRQ1
SL10 bit
Summary of Contents for MB89950 Series
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Page 34: ...20 CHAPTER 2 HANDLING DEVICES ...
Page 134: ...120 CHAPTER 6 WATCHDOG TIMER ...
Page 236: ...222 CHAPTER 10 UART ...
Page 276: ...262 CHAPTER 12 LCD CONTROLLER DRIVER ...
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