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Intel
®
IXP45X and Intel
®
IXP46X Product Line of Network Processors
August 2006
Developer’s Manual
Order Number: 306262-004US
773
Universal Asynchronous Receiver-Transmitter (UART)—Intel
®
IXP45X and Intel
®
IXP46X
Product Line of Network Processors
14.5.12
Scratch-Pad Register
This read/write register has no effect on the UART. The register is intended as a
scratch-pad register for use by the programmer.
Register Name:
MSR
Hex Offset Address:
0xC800 X018
Reset Hex Value:
0x00000000
Register
Description:
Modem Status Register
Access: Read Only.
31
8
7
6
5
4
3
2
1
0
(Reserved)
DC
D
RI
DSR
CTS
DDC
D
TE
RI
DD
S
R
DC
T
S
Register
MSR
Bits
Name
Description
31:8
(Reserved)
7
DCD
Data Carrier Detect: This bit is the complement of the Data Carrier Detect
(DCD_N) input.
This bit is equivalent to bit OUT2 of the Modem Control register if LOOP in the
MCR is set to 1.
0 = DCD_N pin is 1
1 = DCD_N pin is 0
6
RI
Ring Indicator: This bit is the complement of the ring Indicator (RI_N) input.
This bit is equivalent to bit OUT1 of the Modem Control register if LOOP in the
MCR is set to 1.
0 = RI_N pin is 1
1 = RI_N pin is 0
5
DSR
Data Set Ready: This bit is the complement of the Data Set Ready (DSR_N)
input. This bit is equivalent to bit DTR of the Modem Control register if LOOP in
the MCR is set to 1.
0 = DSR_N pin is 1
1 = DSR_N pin is 0
4
CTS
Clear to Send: This bit is the complement of the Clear to Send (CTS_N) input.
This bit is equivalent to bit RTS of the Modem Control register if LOOP in the
MCR is set to 1.
0 = CTS_N pin is 1
1 = CTS_N pin is 0
3
DDCD
Delta Data Carrier Detect:
0 = No change in DCD_N pin since last read of MSR
1 = DCD_N pin has changed state
2
TERI
Trailing Edge Ring Indicator:
0 = RI_N pin has not changed from 0 to 1 since last read of MSR
1 = RI_N pin has changed from 0 to 1
1
DDSR
Delta Data Set Ready:
0 = No change in DSR_N pin since last read of MSR
1 = DSR_N pin has changed state
0
DCTS
Delta Clear To Send:
0 = No change in CTS_N pin since last read of MSR
1 = CTS_N pin has changed state