MC68HC908MR32 • MC68HC908MR16 Data Sheet, Rev. 6.1
Freescale Semiconductor 91
Chapter 8 External Interrupt (IRQ)

8.1 Introduction

This section describes the external interrupt (IRQ) module, which supports external interrupt functions.

8.2 Features

Features of the IRQ module include:

A dedicated external interrupt pin, IRQ

Hysteresis buffers

8.3 Functional Description

A logic 0 applied to any of the external interrupt pins can latch a CPU interrupt request. Figure 8-1 shows

the structure of the IRQ module.

Figure 8-1. IRQ Module Block Diagram

Addr. Register Name Bit 7654321Bit 0
$003F
IRQ Status/Control Register
(ISCR)
See page 94.
Read:0000
IRQF
0
IMASK1 MODE1
Write:RRRR ACK1
Reset:00000000
R= Reserved

Figure 8-2. IRQ I/O Register Summary

ACK1
IMASK1
DQ
CK
CLR
IRQ
HIGH
INTERRUPT
TO MODE
SELECT
LOGIC
IRQ
LATCH
REQUEST
IRQ
VDD
MODE1
VOLTAGE
DETECT
SYNCHRO-
NIZER