MC908MR16CFUE Datasheet, PDF (91/282 Pages) Freescale Semiconductor, Inc – On-chip programming firmware for use with host personal computer, Clock generator module (CGM)

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.
ACK1
V_DD
D ^CLR Q
SYNCHRO-
IRQ
CK
NIZER
IRQ
LATCH
IMASK1
IRQ
INTERRUPT
REQUEST
Addr.
$003F
MODE1
HIGH
VOLTAGE
DETECT
Figure 8-1. IRQ Module Block Diagram
TO MODE
SELECT
LOGIC
Register Name
IRQ Status/Control Register
(ISCR)
See page 94.
Bit 7
Read: 0
Write: R
Reset: 0
R
6
5
0
0
R
R
0
0
= Reserved
4
3
0
IRQF
R
0
0
Figure 8-2. IRQ I/O Register Summary
2
0
ACK1
0
1
Bit 0
IMASK1 MODE1
0
0
MC68HC908MR32 • MC68HC908MR16 Data Sheet, Rev. 6.1
Freescale Semiconductor
91