XRT7234
E3 UNI FOR ATM
x r
PRELIMINARY
REV. P1.0.0
72
received by the LAPD Receiver. The following table relates the contents of these bit-fields to the LAPD Message
type/size.
Bit 3—Rx CR Type
This “Read-Only” bit-field indicates the state of the C/R bit-field, within octet # 2 of the most recently received LAPD
Message frame.
Bit 2—Rx FCS Error
This “Read-Only” bit-field indicates whether or not the LAPD Receiver has detected an FCS (Frame Check Sequence)
error, in the most recently received LAPD Message frame. This bit-field is set to “0” if the LAPD Receiver does not
detect an FCS error in this LAPD Message frame. Conversely, this bit-field is set to “1” if the LAPD Receiver does
detect an FCS error in this LAPD Message frame.
For a more detailed discussion on the LAPD Receiver’s handling of the FCS bytes, please see Section 7.1.2.5.
Bit 1—EndOfMessage
The LAPD Receiver will assert this “read-only” bit-field, when it has received a complete LAPD Message frame.
This bit-field, along with the “Receipt of New LAPD Message frame” interrupt, serves to inform the local
μ
P
that the
“Receive LAPD Message” buffer contains a new PMDL message that needs to be read and processed.
This bit-field is cleared (to “0”) upon reading this register.
Bit 0—Flag Present
The LAPD Receiver will assert this “read-only” bit-field when it is currently detecting the Flag Sequence octet (7Eh)
in the incoming LAPD channel (e.g., either the GC or the NR byte-field, within each E3 frame). The LAPD Receiver
will negate this bit-field when it is no longer receiving the Flag Sequence octet in the incoming LAPD channel.
3.3.2.42 Tx E3 Configuration Register
Bit 7—Auto Retransmit
This “Read/Write” bit-field allows the user to configure the LAPD Transmitter to either transmit the LAPD Message
frame only once; or repeatedly at one-second intervals.
Writing a “0” to this bit-field configures the LAPD Transmitter to transmit the LAPD Message frame once. Afterwards,
RxLAPDType[1:0]
LAPD Message Frame Type
PMDL Message Size (Information Section)
00
Test Signal Identification Type
76 Bytes
01
Idle Signal Identification Type
76 Bytes
10
CL Path Identification Type
76 Bytes
11
ITU-T Path Identification Type
82 Bytes
Address = 28h, Tx E3 Configuration Register
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Auto Re-transmit
TxLAPD Type[1:0]
DLinNR
NoData Link
TxAIS Enable
TxLOS Enable
MARx
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
1
0
0
0
1
0
0
1