© Koninklijke Philips Electronics N.V. 2005. All rights reserved.
User manual
Rev. 01 — 15 August 2005
20
Philips Semiconductors
UM10139
Volume 1
Chapter 3: System Control Block
3.5 External interrupt inputs
The LPC2141/2/4/6/8 includes four External Interrupt Inputs as selectable pin functions.
The External Interrupt Inputs can optionally be used to wake up the processor from
Power-down mode.
3.5.1 Register
description
The external interrupt function has four registers associated with it. The EXTINT register
contains the interrupt flags, and the EXTWAKEUP register contains bits that enable
individual external interrupts to wake up the microcontroller from Power-down mode. The
EXTMODE and EXTPOLAR registers specify the level and edge sensitivity parameters.
Fig 7.
F
OSC
selection algorithm
True
MIN f
OSC
= 10 MHz
MAX f
OSC
= 25 MHz
True
MIN f
OSC
= 1 MHz
MAX f
OSC
= 50 MHz
MIN f
OSC
= 1 MHz
MAX f
OSC
= 30 MHz
(Figure 7, mode a and/or b)
(Figure 7, mode a)
(Figure 7, mode b)
On-chip PLL used
in application?
ISP used for initial
code download?
External crystal
oscillator used?
True
False
False
False
f
OSC
selection
Table 8:
External interrupt registers
Name
Description
Access Reset
value
Address
EXTINT
The External Interrupt Flag Register contains
interrupt flags for EINT0, EINT1, EINT2 and
EINT3. See
R/W
0
0xE01F C140