External Interrupt Inputs - Philips LPC2119 User Manual

Philips Semiconductors
ARM-based Microcontroller

EXTERNAL INTERRUPT INPUTS

The LPC2119/2129/2292/2294 includes four External Interrupt Inputs as selectable pin functions. The External Interrupt Inputs
can optionally be used to wake up the processor from the Power Down mode.
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 LPC2119/2129/2292/2294 from
Power Down mode. The EXTMODE and EXTPOLAR registers specify the level and edge sensitivity parameters.
Table 14: External Interrupt Registers
Address Name
0xE01FC140 EXTINT
0xE01FC144 EXTWAKE
0xE01FC148 EXTMODE
0xE01FC14C EXTPOLAR
External Interrupt Flag Register (EXTINT - 0xE01FC140)
When a pin is selected for its external interrupt function, the level or edge on that pin selected by its bits in the EXTPOLAR and
EXTMODE registers will set its interrupt flag in this register. This asserts the corresponding interrupt request to the VIC, which
will cause an intrerrupt if interrupts from the pin are enabled.
Writing ones to bits EINT0 through EINT3 in EXTINT register clears the corresponding bits. In level-sensitive mode this action is
efficacious only when the pin is in its innactive state.
System Control Block
The External Interrupt Flag Register contains interrupt flags for EINT0, EINT1,
and EINT2. See Table 15.
The External Interrupt Wakeup Register contains three enable bits that control
whether each external interrupt will cause the processor to wake up from Power
Down mode. See Table 16.
The External Interrupt Mode Register controls whether each pin is edge- or level-
sensitive.
The External Interrupt Polarity Register controls which level or edge on each pin
will cause an interrupt.
LPC2119/2129/2292/2294
Description
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Preliminary User Manual
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January 08, 2004