s908qc16vdse Freescale Semiconductor, Inc, s908qc16vdse Datasheet - Page 79

• Manufacturer Part Number: s908qc16vdse
• Description: M68hc08 Microcontrollers
• Manufacturer: Freescale Semiconductor, Inc

Chapter 7
External Interrupt (IRQ)
7.1 Introduction
The IRQ (external interrupt) module provides a maskable interrupt input.
IRQ functionality is enabled by setting configuration register 2 (CONFIG2) IRQEN bit accordingly. A zero
disables the IRQ function and IRQ will assume the other shared functionalities. A one enables the IRQ
function. See
enabling the IRQ pin.
The IRQ pin shares its pin with general-purpose input/output (I/O) port pins. See
location of this shared pin.
7.2 Features
Features of the IRQ module include:
7.3 Functional Description
A low level applied to the external interrupt request (IRQ) pin can latch a CPU interrupt request.
shows the structure of the IRQ module.
Interrupt signals on the IRQ pin are latched into the IRQ latch. The IRQ latch remains set until one of the
following actions occurs:
The external IRQ pin is falling edge sensitive out of reset and is software-configurable to be either falling
edge or falling edge and low level sensitive. The MODE bit in INTSCR controls the triggering sensitivity
of the IRQ pin.
Freescale Semiconductor
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A dedicated external interrupt pin IRQ
IRQ interrupt control bits
Programmable edge-only or edge and level interrupt sensitivity
Automatic interrupt acknowledge
Internal pullup device
IRQ vector fetch. An IRQ vector fetch automatically generates an interrupt acknowledge signal that
clears the latch that caused the vector fetch.
Software clear. Software can clear the IRQ latch by writing a 1 to the ACK bit in the interrupt status
and control register (INTSCR).
Reset. A reset automatically clears the IRQ latch.
Chapter 4 Configuration Registers (CONFIG1 and CONFIG2)
MC68HC908QC16 • MC68HC908QC8 • MC68HC908QC4 Data Sheet, Rev. 4
for more information on
Figure 7-1
for port
Figure 7-2
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