mc68hc08qa24 Freescale Semiconductor, Inc, mc68hc08qa24 Datasheet - Page 182

• Manufacturer Part Number: mc68hc08qa24
• Description: M68hc08 Microcontrollers
• Manufacturer: Freescale Semiconductor, Inc

External Interrupt (IRQ)
15.4 Functional Description
Technical Data
180
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 these actions occurs:
The external interrupt pin is falling-edge triggered and is software-
configurable to be both falling-edge and low-level triggered. The MODE
bit in the ISCR controls the triggering sensitivity of the IRQ pin.
•
•
•
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 15-1. IRQ Block Diagram
Figure 15-1
D
CK
LATCH
CLR
IRQ
External Interrupt (IRQ)
Q
shows the structure of the IRQ module.
IMASK
SYNCHRO-
VOLTAGE
DETECT
NIZER
HIGH
Freescale Semiconductor
IRQF
MC68HC08QA24
TO CPU FOR
BIL/BIH
INSTRUCTIONS
IRQ
INTERRUPT
REQUEST
TO MODE
SELECT
LOGIC