Interrupts - Philips P89LPC938 User Manual

Philips Semiconductors
Table 20: Boundary status register 0 (BNDSTA0 - address FFEDh) bit description
Bit Symbol
0 BST00
1 BST01
2 BST02
3 BST03
4 BST04
5 BST05
6 BST06
7 BST07

4. Interrupts

The P89LPC938 uses a four priority level interrupt structure. This allows great flexibility in
controlling the handling of the P89LPC938's 15 interrupt sources.
Each interrupt source can be individually enabled or disabled by setting or clearing a bit in
the interrupt enable registers IEN0 or IEN1. The IEN0 register also contains a global
enable bit, EA, which enables all interrupts.
Each interrupt source can be individually programmed to one of four priority levels by
setting or clearing bits in the interrupt priority registers IP0, IP0H, IP1, and IP1H. An
interrupt service routine in progress can be interrupted by a higher priority interrupt, but
not by another interrupt of the same or lower priority. The highest priority interrupt service
cannot be interrupted by any other interrupt source. If two requests of different priority
levels are received simultaneously, the request of higher priority level is serviced.
If requests of the same priority level are pending at the start of an instruction cycle, an
internal polling sequence determines which request is serviced. This is called the
arbitration ranking. Note that the arbitration ranking is only used for pending requests of
the same priority level.
addresses, enable bits, priority bits, arbitration ranking, and whether each interrupt may
wake-up the CPU from a Power-down mode.
User manual
Description
When set, indicates that conversion result for the AD00 pin was inside/outside the
boundary limits. This bit is cleared in software by writing a 1 to this bit.
When set, indicates that conversion result for the AD01 pin was inside/outside the
boundary limits. This bit is cleared in software by writing a 1 to this bit.
When set, indicates that conversion result for the AD02 pin was inside/outside the
boundary limits. This bit is cleared in software by writing a 1 to this bit.
When set, indicates that conversion result for the AD03 pin was inside/outside the
boundary limits. This bit is cleared in software by writing a 1 to this bit.
When set, indicates that conversion result for the AD04 pin was inside/outside the
boundary limits. This bit is cleared in software by writing a 1 to this bit.
When set, indicates that conversion result for the AD05 pin was inside/outside the
boundary limits. This bit is cleared in software by writing a 1 to this bit.
When set, indicates that conversion result for the AD06 pin was inside/outside the
boundary limits. This bit is cleared in software by writing a 1 to this bit.
When set, indicates that conversion result for the AD07 pin was inside/outside the
boundary limits. This bit is cleared in software by writing a 1 to this bit.
Table 22 summarizes the interrupt sources, flag bits, vector
Rev. 03 — 7 June 2005
UM10119
P89LPC938 User manual
© Koninklijke Philips Electronics N.V. 2005. All rights reserved.
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