xr17c152im Exar Corporation, xr17c152im Datasheet - Page 43

• Manufacturer Part Number: xr17c152im
• Description: 5v Pci Bus Dual Uart
• Manufacturer: Exar Corporation

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REV. 1.2.0
MSR[5]: DSR Input Status
This input may be used for auto DTR/DSR flow control function, see
CTS or DTR/DSR) Flow Control Operation” on page 28
is not used, this bit is the compliment of the DSR# input. In the loopback mode, this bit is equivalent to the
DTR# bit in the MCR register. The DSR# input may be used as a general purpose input when the modem
interface is not used.
MSR[6]: RI Input Status
This bit is the compliment of the RI# input. In the loopback mode this bit is equivalent to bit-2 in the MCR
register. The RI# input may be used as a general purpose input when the modem interface is not used.
MSR[7]: CD Input Status
This bit is the compliment of the CD# input. In the loopback mode this bit is equivalent to bit-3 in the MCR
register. The CD# input may be used as a general purpose input
The upper four bits 4-7 of this register sets the delay in number of bits time for the auto RS485 turn around
from transmit to receive.
MSR [7:4]
When Auto RS485 feature is enabled (FCTR bit-5=1) and RTS# output is connected to the enable input of a
RS-485 transceiver. These 4 bits select from 0 to 15 bit-time delay after the end of the last stop-bit of the last
transmitted character. This delay controls when to change the state of RTS# output. This delay is very useful in
long-cable networks.
4.8.11
T
ABLE
Modem Status Register (MSR) - Write-Only
16: A
UTO
Table 16
MSR[7]
RS485 H
0
0
0
0
0
9
0
0
1
1
1
1
1
1
1
1
shows the selection. The bits are enabled by EFR bit-4.
MSR[6]
ALF
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
-
DUPLEX
MSR[5]
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
D
IRECTION
MSR[4]
43
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
for complete details. If automatic hardware flow control
C
ONTROL
D
ELAY IN
D
ELAY FROM
“Section 4.4, Automatic Hardware (RTS/
D
ATA
10
11
12
13
14
15
0
1
2
3
4
5
6
7
8
9
B
IT
T
(
S
RANSMIT
) T
5V PCI BUS DUAL UART
IME
-
TO
-R
ECEIVE
XR17C152