MC68HC908GT16 Datasheet, PDF (190/412 Pages) Motorola, Inc – Microcontrollers

External Interrupt (IRQ)
12.4 Functional Description
A logic 0 applied to the external interrupt pin can latch a central
processor unit (CPU) interrupt request. Figure 12-1 shows the structure
of the IRQ module.
Interrupt signals on the IRQ1 pin are latched into the IRQ latch. An
interrupt latch remains set until one of the following actions occurs:
• 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 (INTSCR). Writing a logic 1 to the ACK bit clears
the IRQ latch.
• Reset — A reset automatically clears the interrupt latch.
RESET
ACK
VECTOR
FETCH
DECODER
V_DD
INTERNAL
PULLUP
DEVICE
IRQ
V_DD
CLR
D
Q
CK
SYNCHRONIZER
IMASK
MODE
HIGH
VOLTAGE
DETECT
Figure 12-1. IRQ Module Block Diagram
TO CPU FOR
BIL/BIH
INSTRUCTIONS
IRQF
IRQ
INTERRUPT
REQUEST
TO MODE
SELECT
LOGIC
Technical Data
190
MC68HC908GT16 • MC68HC908GT8 — Rev. 2
External Interrupt (IRQ)
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