SC16C850V NXP Semiconductors, SC16C850V Datasheet - Page 27

• Manufacturer Part Number: SC16C850V
• Description: XScale VLIO bus interface
• Manufacturer: NXP Semiconductors

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SC16C850V_4
Product data sheet
7.8 Modem Status Register (MSR)
Table 20.
This register shares the same address as EFCR register. This is a read-only register and
it provides the current state of the control interface signals from the modem, or other
peripheral device to which the SC16C850V is connected. Four bits of this register are
used to indicate the changed information. These bits are set to a logic 1 whenever a
control input from the modem changes state. These bits are set to a logic 0 whenever the
CPU reads this register.
When write, the data will be written to EFCR register.
Table 21.
[1]
Bit
0
Bit
7
6
5
4
3
2
1
0
Whenever any MSR bit 3:0 is set to logic 1, a Modem Status Interrupt will be generated.
Symbol Description
LSR[0]
Symbol
MSR[7]
MSR[6]
MSR[5]
MSR[4]
MSR[3]
MSR[2]
MSR[1]
MSR[0]
Line Status Register bits description
Modem Status Register bits description
Single UART with 128-byte FIFOs, IrDA, and XScale VLIO bus interface
Receive data ready.
Description
CD. During normal operation, this bit is the complement of the CD input.
Reading this bit in the loopback mode produces the state of MCR[3] (OP2).
RI. During normal operation, this bit is the complement of the RI input. Reading
this bit in the loopback mode produces the state of MCR[2] (OP1).
DSR. During normal operation, this bit is the complement of the DSR input.
During the loopback mode, this bit is equivalent to MCR[0] (DTR).
CTS. During normal operation, this bit is the complement of the CTS input.
During the loopback mode, this bit is equivalent to MCR[1] (RTS).
logic 0 = no data in Receive Holding Register or FIFO (normal default
condition)
logic 1 = data has been received and is saved in the Receive Holding Register
or FIFO
CD
RI
DSR
CTS
logic 0 = no CD change (normal default condition)
logic 1 = the CD input to the SC16C850V has changed state since the last
time it was read. A modem Status Interrupt will be generated.
logic 0 = no RI change (normal default condition)
logic 1 = the RI input to the SC16C850V has changed from a logic 0 to a
logic 1. A modem Status Interrupt will be generated.
logic 0 = no DSR change (normal default condition)
logic 1 = the DSR input to the SC16C850V has changed state since the last
time it was read. A modem Status Interrupt will be generated.
logic 0 = no CTS change (normal default condition)
logic 1 = the CTS input to the SC16C850V has changed state since the last
time it was read. A modem Status Interrupt will be generated.
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Rev. 04 — 14 January 2008
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…continued
SC16C850V
© NXP B.V. 2008. All rights reserved.
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