mc68hc908gr8vp Freescale Semiconductor, Inc, mc68hc908gr8vp Datasheet - Page 117

• Manufacturer Part Number: mc68hc908gr8vp
• Description: M68hc08 Microcontrollers Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

Chapter 12
External Interrupt (IRQ)
12.1 Introduction
The IRQ (external interrupt) module provides a maskable interrupt input.
12.2 Features
Features of the IRQ module include:
12.3 Functional Description
A logic 0 applied to the external interrupt pin can latch a CPU interrupt request.
structure of the IRQ module.
Interrupt signals on the IRQ pin are latched into the IRQ latch. An interrupt latch remains set until one of
the following actions occurs:
The external interrupt pin is falling-edge-triggered out of reset and is software-configurable to be either
falling-edge or falling-edge and low-level-triggered. The MODE bit in the INTSCR controls the triggering
sensitivity of the IRQ pin.
When an interrupt pin is edge-triggered only (MODE = 0), the interrupt remains set until a vector fetch,
software clear, or reset occurs.
Freescale Semiconductor
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A dedicated external interrupt pin (IRQ)
IRQ interrupt control bits
Hysteresis buffer
Programmable edge-only or edge and level interrupt sensitivity
Automatic interrupt acknowledge
Internal pullup resistor
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.
MC68HC908GR8 • MC68HC908GR4 Data Sheet, Rev. 7
Figure 12-1
shows the
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