© Koninklijke Philips Electronics N.V. 2005. All rights reserved.
User manual
Rev. 01 — 15 August 2005
127
Philips Semiconductors
UM10139
Volume 1
Chapter 10: UART1
10.3.12 UART1 Modem Status Register (U1MSR - 0xE001 0018), LPC2144/6/8
only
The U1MSR is a read-only register that provides status information on the modem input
signals. U1MSR[3:0] is cleared on U1MSR read. Note that modem signals have no direct
affect on UART1 operation, they facilitate software implementation of modem signal
operations.
10.3.13 UART1 Scratch pad register (U1SCR - 0xE001 001C)
The U1SCR has no effect on the UART1 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 U1SCR has occurred.
10.3.14 UART1 Auto-baud Control Register (U1ACR - 0xE001 0020)
The UART1 Auto-baud Control Register (U1ACR) 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 128: UART1 Modem Status Register (U1MSR - address 0xE001 0018), LPC2144/6/8 only bit description
Bit Symbol
Value Description
Reset value
0
Delta CTS
0
Set upon state change of input CTS. Cleared on an U1MSR read.
0
No change detected on modem input, CTS.
1
State change detected on modem input, CTS.
1
Delta DSR
0
Set upon state change of input DSR. Cleared on an U1MSR read.
0
No change detected on modem input, DSR.
1
State change detected on modem input, DSR.
2
Trailing Edge RI
0
Set upon low to high transition of input RI. Cleared on an U1MSR read.
0
No change detected on modem input, RI.
1
Low-to-high transition detected on RI.
3
Delta DCD
0
Set upon state change of input DCD. Cleared on an U1MSR read.
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 U1MCR[1] in modem loopback mode.
0
5
DSR
Data Set Ready State. Complement of input signal DSR. This bit is connected
to U1MCR[0] in modem loopback mode.
0
6
RI
Ring Indicator State. Complement of input RI. This bit is connected to
U1MCR[2] in modem loopback mode.
0
7
DCD
Data Carrier Detect State. Complement of input DCD. This bit is connected to
U1MCR[3] in modem loopback mode.
0
Table 129: UART1 Scratch pad register (U1SCR - address 0xE001 0014) bit description
Bit
Symbol
Description
Reset value
7:0
Pad
A readable, writable byte.
0x00