CD1865 Datasheet, PDF (125/150 Pages) Intel Corporation – Intelligent Eight-Channel Communications Controller

Intelligent Eight-Channel Communications Controller — CD1865
9.4.17
Modem Change Option Register 2
Register Name: MCOR2
Register Description: Modem Change Option Register 2
Default Value: 0
Access: Read/Write
Bit 7
Bit 6
Bit 5
Bit 4
DSRod
CDod
CTSod
0
Bit 3
0
Bit 2
0
8-Bit Hex Address: $11
Intel Hex Address: $22
Motorola Hex Address: $23
Bit 1
Bit 0
0
0
This register is used to define the current state change options to be monitored.
Bit
Bit 7
Bit 6
Bit 5
Bits 4:0
Description
DSRod is a ‘1’: Detect low-to-high transition on DSR* Input (one-to-zero transition DSR (MSVR) bit).
CDod is a ‘1’: Detect low-to-high transition on CD* Input (one-to-zero transition of CD (MSVR) bit).
CTSod is a ‘1’: Detect low-to-high transition on CTS* Input (one-to-zero transition of CTS (MSVR) bit).
Must be a ‘0’.
9.4.18
Modem Signal Value Register
Register Name: MSVR
Register Description: Modem Signal Value Register
Default Value: 0
Access: Read/Write
Bit 7
Bit 6
Bit 5
Bit 4
DSR
CD
CTS
N/U
Bit 3
N/U
Bit 2
N/U
8-Bit Hex Address: $28
Intel Hex Address: $50
Motorola Hex Address: $51
Bit 1
Bit 0
DTR
RTS
This register is read to determine the current input levels on the Modem Input pins. It is written to
supply an output value for the RTS* and DTR* pins. The register bits have the opposite polarities
from the actual states on the individual pins. Writing a ‘1’ causes the pin to go to nominal zero
volts.
Bit
Bit 7
Bit 6
Bit 5
Bits 4:2
Bit 1
Bit 0
Description
DSR: Current state of Data-Set-Ready Input.
CD: Current state of Carrier Detect Input.
CTS: Current state of Clear-to-Send Input.
Not used.
DTR: Current state of Data-Terminal-Ready Output.
RTS: Current state of Request-to-Send Output.
Datasheet
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