10-12 Chapter 10 External Interrupt Circuit 1 (Edge)
MB89190/190A series
10.
5 Interruptfor ExternalInterruptCircuit1
The interrupt factor for the external interrupt circuit 1 is the detection of the
specified edge of the signal input to the external interrupt pin.
T Interrupt when external interrupt circuit 1 operating
When the specified edge of the external interrupt input is detected, the corresponding external interrupt
request flag bit (EIC1, EIC2: EIR0 to EIR2) is set to 1. At this point, when the corresponding interrupt
request enable bit is Enable (EIC1, EIC2: EIE0 to EIE2 = 1), an interrupt request (IRQ0 to IRQ2) to the
CPU occurs. Write 0 to the external interrupt request flag bit of the corresponding interrupt-processing
routine to clear the interrupt request.
Check:
When no edge detection is selected using the edge detection selection bit, the input at this point is held
before the internal edge detection section. Consequently, if an edge is selected with that specification
in effect, an edge may be detected to set the external interrupt request flag bit to 1.
When enabling the interrupt (EIC1, EIC2: EIE0 to EIE2 = 1) after canceling the reset, always clear
(EIR0 to EIR2 = 0) the external interrupt flag bit. Also, control cannot be returned from the interrupt
processing when the external interrupt request flag bit is 1 and the interrupt request enable bit is
Enable. Always clear the external interrupt request flag bit during operation of the interrupt-processing
routine.
Remarks:
When no edge detection is selected, edge selection is performed with the interrupt request output
disabled. After this, always clear the external interrupt request flag bit.
The external interrupt request flag bit is set when the edge polarity matches irrespective of the value of
the interrupt request enable bits (EIE0 to EIE2).
Cancellation of the Stop mode due to an interrupt is only possible for external interrupt circuits 1 and 2.
The interrupt request occurs immediately when the interrupt request enable bit is changed from Disable
to Enable (0
→ 1) with the external interrupt request flag bit set to 1.
T Registers and vector table related to interrupt for external interrupt circuit 1
Table 10-5 Registers and Vector Table Related to Interrupt for External Interrupt Circuit 1
Interrupt level setting register
Vector table address
Interrupt
name
Register
Bits to set
Higher order
Lower order
IRQ0
L01 (bit 1)
L00 (bit 0)
FFFAH
FFFBH
IRQ1
L11 (bit 3)
L10 (bit 2)
FFF8H
FFF9H
IRQ2
ILR1 (007CH)
L21 (bit 5)
L20 (bit 4)
FFF6H
FFF7H
Reference: For the interrupt operation, see
Section 3.4.2.