Operations And Setting Procedure Example - Fujitsu 8FX Hardware Manual

MB95630H Series
12.6

Operations and Setting Procedure Example

This section describes the operations of the external interrupt circuit.
■ Operations of External Interrupt Circuit
When the polarity of an edge of a signal input from one of the external interrupt pins (INTn,
INTn+1) matches the polarity of the edge selected by the external interrupt control register
(EIC:SL0[1:0] or SL1[1:0]), the corresponding external interrupt request flag bit (EIC:EIR0 or
EIR1) is set to "1" and the interrupt request is generated.
Always set the interrupt request enable bit to "0" when not using an external interrupt to wake
up the device from standby mode.
When setting the edge polarity select bit (SL00, SL01 or SL10, SL11), set the interrupt request
enable bit (EIE0 or EIE1) to "0" to prevent the interrupt request from being generated
accidentally. Also clear the interrupt request flag bit (EIR0 or EIR1) to "0" after changing the
edge polarity.
Figure 12.6-1 shows the operations for setting the INTn pin as an external interrupt input.
Input waveform
to INTn pin
EIR0 bit
EIE0 bit
SL01 bit
SL00 bit
IRQ
MN702-00009-2v0-E
Figure 12.6-1 Operations of External Interrupt
No edge Rising edge
detection
FUJITSU SEMICONDUCTOR LIMITED
CHAPTER 12 EXTERNAL INTERRUPT CIRCUIT
12.6 Operations and Setting Procedure
Interrupt request flag bit cleared
by program
Falling edge
Example
Both edges
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