SC16C2550BIA44,512 NXP Semiconductors, SC16C2550BIA44,512 Datasheet - Page 23

• Manufacturer Part Number: SC16C2550BIA44,512
• Description: IC UART DUAL W/FIFO 44-PLCC
• Manufacturer: NXP Semiconductors

Specifications of SC16C2550BIA44,512

• Features: False-start Bit Detection
• Number Of Channels: 2, DUART
• Fifo's: 16 Byte
• Voltage - Supply: 3.5 V ~ 4.5 V
• With Auto Flow Control: Yes
• With False Start Bit Detection: Yes
• With Modem Control: Yes
• With Cmos: Yes
• Mounting Type: Surface Mount
• Package / Case: 44-LCC (J-Lead)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 935274407512; SC16C2550BIA44; SC16C2550BIA44

NXP Semiconductors
SC16C2550B_5
Product data sheet
7.8 Modem Status Register (MSR)
Table 19.
This register provides the current state of the control interface signals from the modem or
other peripheral device to which the SC16C2550B 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.
Table 20.
[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
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
Description
Receive data ready.
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
5 V, 3.3 V and 2.5 V dual UART, 5 Mbit/s (max.), with 16-byte FIFOs
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
logic 0 = no CD change (normal default condition)
logic 1 = the CD input to the SC16C2550B 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 SC16C2550B 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 SC16C2550B 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 SC16C2550B has changed state since the
last time it was read. A modem Status Interrupt will be generated.
Rev. 05 — 12 January 2009
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SC16C2550B
© NXP B.V. 2009. All rights reserved.
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