MC68HC708AS48 FREESCALE [Freescale Semiconductor, Inc], MC68HC708AS48 Datasheet - Page 178

• Manufacturer Part Number: MC68HC708AS48
• Description: Advance Information
• Manufacturer: FREESCALE [Freescale Semiconductor, Inc]

External Interrupt
14.4 Functional Description
Advance Information
178
IRQ/V
PP
DECODER
VECTOR
FETCH
ACK
A logic 0 applied to the external interrupt pin can latch a CPU interrupt
request.
Interrupt signals on the IRQ/V
interrupt latch remains set until one of the following actions occurs:
•
•
•
V
MODE
DD
Vector fetch — A vector fetch automatically generates an interrupt
acknowledge signal that clears the latch that caused the vector
fetch.
Software clear — Software can clear an interrupt latch by writing
to the appropriate acknowledge bit in the interrupt status and
control register (ISCR). Writing a logic 1 to the ACK bit clears the
IRQ latch.
Reset — A reset automatically clears both interrupt latches.
Figure 14-1. IRQ Block Diagram
Figure 14-1
D
CK
LATCH
CLR
IRQ
Q
External Interrupt
shows the structure of the IRQ module.
IMASK
PP
pin are latched into the IRQ latch. An
SYNCHRO-
VOLTAGE
DETECT
NIZER
HIGH
MC68HC708AS48
IRQF
TO CPU FOR
BIL/BIH
INSTRUCTIONS
IRQ
INTERRUPT
REQUEST
TO MODE
SELECT
LOGIC
MOTOROLA
—
Rev. 4.0