sc16c850iet NXP Semiconductors, sc16c850iet Datasheet - Page 30

• Manufacturer Part Number: sc16c850iet
• Description: Sc16c850 2.5 V To 3.3 V Uart, 5 Mbit/s Max. With 128-byte Fifos, Infrared Irda , And 16 Mode Or 68 Mode Parallel Bus Interface
• Manufacturer: NXP Semiconductors

NXP Semiconductors
SC16C850_1
Product data sheet
7.8 Modem Status Register (MSR)
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 SC16C850 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
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
MSR[7]
MSR[6]
MSR[5]
MSR[4]
MSR[3]
MSR[2]
MSR[1]
MSR[0]
Modem Status Register bits description
2.5 V to 3.3 V UART with 128-byte FIFOs and IrDA encoder/decoder
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).
CD
RI
DSR
CTS
Rev. 01 — 10 January 2008
logic 0 = no CD change (normal default condition)
logic 1 = the CD input to the SC16C850 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 SC16C850 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 SC16C850 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 SC16C850 has changed state since the
last time it was read. A modem Status Interrupt will be generated.
[1]
[1]
[1]
[1]
SC16C850
© NXP B.V. 2008. All rights reserved.
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