sc16c652b NXP Semiconductors, sc16c652b Datasheet - Page 24

• Manufacturer Part Number: sc16c652b
• Description: 5v, 3.3 V And 2.5v Dual Uart, 5 Mbit/s Max. ,with 32-byte Fifos And Infrared Irda Encoder/decoder
• Manufacturer: NXP Semiconductors

Philips Semiconductors
SC16C652B_4
Product data sheet
7.8 Modem Status Register (MSR)
7.9 Scratchpad Register (SPR)
This register provides the current state of the control interface signals from the modem, or
other peripheral device to which the SC16C652B 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 22:
[1]
The SC16C652B provides a temporary data register to store 8 bits of user information.
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
Description
CD. During normal operation, this bit is the complement of the CD input.
Reading this bit in the loop-back 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 loop-back mode produces the state of MCR[2] (OP1).
DSR. During normal operation, this bit is the complement of the DSR input.
During the loop-back mode, this bit is equivalent to MCR[0] (DTR).
CTS. During normal operation, this bit is the complement of the CTS input.
During the loop-back mode, this bit is equivalent to MCR[1] (RTS).
Rev. 04 — 1 September 2005
CD
RI
DSR
CTS
logic 0 = no CD change (normal default condition)
logic 1 = the CD input to the SC16C652B 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 SC16C652B 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 SC16C652B 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 SC16C652B has changed state since the
last time it was read. A modem Status Interrupt will be generated.
[1]
[1]
[1]
[1]
Dual UART with 32-byte FIFOs and IrDA encoder/decoder
© Koninklijke Philips Electronics N.V. 2005. All rights reserved.
SC16C652B
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