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UM10316_0
© NXP B.V. 2008. All rights reserved.
User manual
Rev. 00.06 — 17 December 2008
284 of 571
NXP Semiconductors
UM10316
Chapter 19: LPC29xx Universal Asynchronous Receiver/Transmitter
4.11 UARTn Scratch Pad Register
The UnSCR has no effect on the UARTn operation. This register can be written and/or
read at user’s discretion. There is no provision in the interrupt interface that would indicate
to the host that a read or write of the UnSCR has occurred.
4.12 UARTn Auto-baud Control Register
The UARTn Auto-baud Control Register (UnACR) controls the process of measuring the
incoming clock/data rate for the baud rate generation and can be read and written at
user’s discretion.
Table 241: UARTn Modem Status Register (U0MSR - address 0xE004 5018,
U1MSR - 0xE004 6018, Read Only) bit description
Bit Symbol Value Description
Reset
Value
0
Delta
CTS
Set upon state change of input CTS. Cleared on an MSR read.
0
0
No change detected on modem input, CTS.
1
State change detected on modem input, CTS.
1
Delta
DSR
Set upon state change of input DSR. Cleared on an MSR read.
0
0
No change detected on modem input, DSR.
1
State change detected on modem input, DSR.
2
Trailing
Edge RI
Set upon low to high transition of input RI. Cleared on an MSR read. 0
0
No change detected on modem input, RI.
1
Low-to-high transition detected on RI.
3
Delta
DCD
Set upon state change of input DCD. Cleared on an MSR read.
0
0
No change detected on modem input, DCD.
1
State change detected on modem input, DCD.
4
CTS
Clear To Send State. Complement of input signal CTS. This bit is
connected to MCR[1] in modem loopback mode.
0
5
DSR
Data Set Ready State. Complement of input signal DSR. This bit is
connected to MCR[0] in modem loopback mode.
0
6
RI
Ring Indicator State. Complement of input RI. This bit is connected
to MCR[2] in modem loopback mode.
0
7
DCD
Data Carrier Detect State. Complement of input DCD. This bit is
connected to MCR[3] in modem loopback mode.
0
Table 242. UARTn Scratch Pad Register (U0SCR - address 0xE004 501C,
U1SCR - 0xE004 601C) bit description
Bit Symbol Description
Reset
Value
7:0 Pad
A readable, writable byte.
0x00