
UM10375
All information provided in this document is subject to legal disclaimers.
© NXP B.V. 2011. All rights reserved.
User manual
Rev. 3 — 14 June 2011
185 of 368
NXP Semiconductors
UM10375
Chapter 12: LPC13xx UART
12.6.5 UART Interrupt Identification Register (U0IIR - 0x4004 8008, Read
Only)
U0IIR provides a status code that denotes the priority and source of a pending interrupt.
The interrupts are frozen during a U0IIR access. If an interrupt occurs during a U0IIR
access, the interrupt is recorded for the next U0IIR access.
Bits U0IIR[9:8] are set by the auto-baud function and signal a time-out or end of auto-baud
condition. The auto-baud interrupt conditions are cleared by setting the corresponding
Clear bits in the Auto-baud Control Register.
9
ABTOINTEN
Enables the auto-baud time-out interrupt.
0
0
Disable auto-baud time-out Interrupt.
1
Enable auto-baud time-out Interrupt.
31:10 -
Reserved, user software should not write ones to
reserved bits. The value read from a reserved bit is not
defined.
-
Table 198. UART Interrupt Enable Register (U0IER - address 0x4000 8004 when DLAB = 0) bit
description
…continued
Bit
Symbol
Value
Description
Reset
value
Table 199. UART Interrupt Identification Register (U0IIR - address 0x4004 8008, Read Only)
bit description
Bit
Symbol
Value Description
Reset
value
0
INTSTATUS
Interrupt status. Note that U0IIR[0] is active low. The
pending interrupt can be determined by evaluating
U0IIR[3:1].
1
0
At least one interrupt is pending.
1
No interrupt is pending.
3:1
INTID
Interrupt identification. U0IER[3:1] identifies an interrupt
corresponding to the UART Rx FIFO. All other combinations
of U0IER[3:1] not listed below are reserved (100,101,111).
0
0x3
1 - Receive Line Status (RLS).
0x2
2a - Receive Data Available (RDA).
0x6
2b - Character Time-out Indicator (CTI).
0x1
3 - THRE Interrupt.
0x0
4 - Modem interrupt.
5:4
-
Reserved, user software should not write ones to reserved
bits. The value read from a reserved bit is not defined.
-
7:6
FIFOEN
These bits are equivalent to U0FCR[0].
0
8
ABEOINT
End of auto-baud interrupt. True if auto-baud has finished
successfully and interrupt is enabled.
0
9
ABTOINT
Auto-baud time-out interrupt. True if auto-baud has timed
out and interrupt is enabled.
0
31:10 -
Reserved, user software should not write ones to reserved
bits. The value read from a reserved bit is not defined.
-