
CD2481
—
Programmable Four-Channel Communications Controller
156
Datasheet
CSR -
–
X.21 Mode
Bit 7
Receiver enabled status
0 = Receiver disabled.
1 = Receiver enabled.
Bit 6
Reserved
–
returns
‘
0
’
when read.
Bit 5
Receive special
This bit, when set, indicates that the CD2481 is currently in a steady state condition.
Such conditions generate a receive special character interrupt.
Bit 4
Reserved
–
returns
‘
0
’
when read.
Bit 3
Transmitter enabled status
0 = Transmitter disabled.
1 = Transmitter enabled.
Bit 2
Reserved
–
returns
‘
0
’
when read.
Bit 1
Transmit special
This bit, when set, indicates that the CD2481 is currently transmitting an ETC com-
mand, as defined in COR2.
Bit 0
Reserved
–
returns
‘
0
’
when read.
CSR
–
Async-HDLC/PPP Mode
Bit 7
RxEn
–
Receiver enabled status
When set, the receiver is enabled.
When clear, the receiver is disabled.
Register Name: CSR
Register Description: Channel Status Register
Default Value: x
’
00
Access: Byte Read/Write
Intel Hex Address: x
’
19
Motorola Hex Address: x
’
1A
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
RxEn
0
RxSpc
0
TxEn
0
TxSpc
0
Register Name: CSR
Register Description: Channel Status Register
Default Value: x
’
00
Access: Byte Read/Write
Intel Hex Address: x
’
19
Motorola Hex Address: x
’
1A
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
RxEn
RxFloff
RxFrame
Ridle
TxEn
TxFloff
TxFrame
Tidle