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UM10316_0
© NXP B.V. 2008. All rights reserved.
User manual
Rev. 00.06 — 17 December 2008
106 of 571
NXP Semiconductors
UM10316
Chapter 10: LPC29xx general system control
A set of software-accessible variables is provided for each interrupt source to control and
observe interrupt request generation. In general, a pair of read-only registers is used for
each event that leads to an interrupt request:
•
STATUS captures the event. The variable is typically set by a hardware event and
cleared by the software ISR, but for test purposes it can also be set by software
•
ENABLE enables the assertion of an interrupt-request output signal for the captured
event
In conjunction with the STATUS/ENABLE variables, commands are provided to set and
clear the variable state through a software write-action to write-only registers. These
commands are SET_STATUS, CLR_STATUS, SET_ENABLE and CLR_ENABLE.
The event signal is logically OR-ed with its associated SET_STATUS register bit, so both
events writing to the SET_STATUS register sets the STATUS register.
Typically, the result of multiple STATUS/ENABLE pairs is logically OR-ed per functional
group, forming an interrupt request signal towards the Vectored Interrupt Controller.
6.1 Interrupt registers
A list is provided for each function in the detailed block-description part of this document,
containing the interrupt sources for that function. A table is also provided to indicate the bit
positions per interrupt source. These positions are identical for all the six registers
INT_STATUS, INT_ENABLE, INT_SET_STATUS, INT_CLEAR_STATUS,
INT_SET_ENABLE and INT_CLEAR_ENABLE.
Up to 32 interrupt bits are available for each register.
Fig 24. Interrupt device architecture
31
2
1
0
STATUS
&
SET
STATUS
CLEAR
STATUS
ENABLE
SET
ENABLE
CLEAR
ENABLE
>1
>1
Event
Interrupt
Request
Control
Interface