XC908AS60ACFU Motorola Semiconductor Products, XC908AS60ACFU Datasheet - Page 236

• Manufacturer Part Number: XC908AS60ACFU
• Description: MC68HC908AZ60A, MC68HC908AS60A Hcmos Microcontroller Unit Technical Data
• Manufacturer: Motorola Semiconductor Products

External Interrupt Module (IRQ)
17.4 Functional Description
Technical Data
236
IRQ
DECODER
VECTOR
FETCH
ACK
A logic 0 applied to the external interrupt pin can latch a CPU interrupt
request.
Interrupt signals on the IRQ pin are latched into the IRQ latch. An
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 17-1. IRQ Block Diagram
Figure 17-1
D
CK
LATCH
External Interrupt Module (IRQ)
CLR
IRQ
Q
shows the structure of the IRQ module.
IMASK
SYNCHRO-
VOLTAGE
DETECT
NIZER
HIGH
MC68HC908AZ60A — Rev 2.0
IRQF
TO CPU FOR
BIL/BIH
INSTRUCTIONS
IRQ
INTERRUPT
REQUEST
TO MODE
SELECT
LOGIC
MOTOROLA