LPC2131_32_34_36_38 All information provided in this document is subject to legal disclaimers. © NXP B.V. 2011. All rights reserved.
Product data sheet Rev. 5.1 — 29 July 2011 15 of 45
NXP Semiconductors
LPC2131/32/34/36/38
Single-chip 16/32-bit microcontrollers
6.5 Interrupt controller
The Vectored Interrupt Controller (VIC) accepts all of the interrupt request inputs and
categorizes them as Fast Interrupt reQuest (FIQ), vectored Interrupt ReQuest (IRQ), and
non-vectored IRQ as defined by programmable settings. The programmable assignment
scheme means that priorities of interrupts from the various peripherals can be dynamically
assigned and adjusted.
FIQ has the highest priority. If more than one request is assigned to FIQ, the VIC
combines the requests to produce the FIQ signal to the ARM processor. The fastest
possible FIQ latency is achieved when only one request is classified as FIQ, because then
the FIQ service routine can simply start dealing with that device. But if more than one
request is assigned to the FIQ class, the FIQ service routine can read a word from the VIC
that identifies which FIQ source(s) is (are) requesting an interrupt.
Vectored IRQs have the middle priority. Sixteen of the interrupt requests can be assigned
to this category. Any of the interrupt requests can be assigned to any of the 16 vectored
IRQ slots, among which slot 0 has the highest priority and slot 15 has the lowest.
Non-vectored IRQs have the lowest priority.
The VIC combines the requests from all the vectored and non-vectored IRQs to produce
the IRQ signal to the ARM processor. The IRQ service routine can start by reading a
register from the VIC and jumping there. If any of the vectored IRQs are requesting, the
VIC provides the address of the highest-priority requesting IRQs service routine,
otherwise it provides the address of a default routine that is shared by all the non-vectored
IRQs. The default routine can read another VIC register to see what IRQs are active.
6.5.1 Interrupt sources
Table 4 lists the interrupt sources for each peripheral function. Each peripheral device has
one interrupt line connected to the Vectored Interrupt Controller, but may have several
internal interrupt flags. Individual interrupt flags may also represent more than one
interrupt source.
Table 4. Interrupt sources
Block Flag(s) VIC channel #
WDT Watchdog Interrupt (WDINT) 0
- Reserved for software interrupts only 1
ARM Core EmbeddedICE, DbgCommRX 2
ARM Core EmbeddedICE, DbgCommTX 3
TIMER0 Match 0 to 3 (MR0, MR1, MR2, MR3)
Capture 0 to 3 (CR0, CR1, CR2, CR3)
4
TIMER1 Match 0 to 3 (MR0, MR1, MR2, MR3)
Capture 0 to 3 (CR0, CR1, CR2, CR3)
5
UART0 RX Line Status (RLS)
Transmit Holding Register empty (THRE)
RX Data Available (RDA)
Character Time-out Indicator (CTI)
6
