UM10503
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User manual
Rev. 1.3 — 6 July 2012
988 of 1269
NXP Semiconductors
UM10503
Chapter 38: LPC43xx UART1
38.6.5 UART1 Interrupt Identification Register
The IIR provides a status code that denotes the priority and source of a pending interrupt.
The interrupts are frozen during an IIR access. If an interrupt occurs during an IIR access,
the interrupt is recorded for the next IIR access.
7
CTSIE
CTS Interrupt Enable. If auto-cts mode is enabled this bit enables/disables the modem
status interrupt generation on a CTS1 signal transition. If auto-cts mode is disabled a
CTS1 transition will generate an interrupt if Modem Status Interrupt Enable (IER[3]) is
set.
In normal operation a CTS1 signal transition will generate a Modem Status Interrupt
unless the interrupt has been disabled by clearing the IER[3] bit in the IER register. In
auto-cts mode a transition on the CTS1 bit will trigger an interrupt only if both the IER[3]
and IER[7] bits are set.
0
0
Disable the CTS interrupt.
1
Enable the CTS interrupt.
8
ABEOIE
Enables the end of auto-baud interrupt.
0
0
Disable end of auto-baud Interrupt.
1
Enable end of auto-baud Interrupt.
9
ABTOIE
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.
NA
Table 853: UART1 Interrupt Enable Register when DLAB = 0 (IER - address 0x4008 2004) bit description
Bit
Symbol
Value
Description
Reset
value
Table 854: UART1 Interrupt Identification Register (IIR - address 0x4008 2008) bit description
Bit
Symbol
Value Description
Reset
value
0
INTSTATUS
Interrupt status. Note that IIR[0] is active low. The pending interrupt can be
determined by evaluating IIR[3:1].
1
0
At least one interrupt is pending.
1
No interrupt is pending.
3:1
INTID
Interrupt identification. IER[3:1] identifies an interrupt corresponding to the
UART1 Rx or TX FIFO. All other combinations of IER[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.
NA
7:6
FIFOENABL
E
Copies of FCR[0].
0