XRT72L52 Datasheet, PDF (94/480 Pages) Exar Corporation – TWO CHANNEL DS3/E3 FRAMER IC WITH HDLC CONTROLLER

XRT72L52 TWO CHANNEL DS3/E3 FRAMER IC WITH HDLC CONTROLLER
REV. P1.1.3
áç
PRELIMINARY
field indicates that the LAPD Message Reception
Complete interrupt has occurred since the last read of
this register.
NOTE: For more information on the LAPD Receiver, please
see Section 3.3.3.2.
2.4.2.15 Receive DS3 LAPD Status Register
RXDS3 LAPD STATUS REGISTER (ADDRESS = 0X19)
BIT 7
BIT 6
BIT 5
BIT 4
BIT 3
BIT 2
BIT 1
BIT 0
Not Used
RxAbort
RxLAPDType[1:0}
RxCR Type RxFCS Error End of Flag Present
Message
RO
RO
RO
RO
RO
RO
RO
RO
0
0
0
0
0
0
0
0
Bit 6 - RxAbort (Receive Abort Sequence)
This Read-Only bit-field indicates whether or not the
LAPD Receiver has detected the occurrence of an
Abort Sequence (e.g., a string of seven or more con-
secutive "1’s") from the remote LAPD Transmitter. A
"0" in this bit-field indicates that no Abort-Sequence
has been detected. A "1" in this bit-field indicates that
the Abort-Sequence has been detected.
NOTE: For more information on the LAPD Receiver, please
see Section 3.3.3.2.
Bits, 5 and 4 - RxLAPDType[1, 0]
These two Read Only bit-fields combine to indicate
the type of LAPD Message frame that has been re-
ceived by the LAPD Receiver. The relationship be-
tween these two bit-fields and the LAPD Message
Type follows:
BIT 5 BIT 4
MESSAGE TYPE
MESSAGE LENGTH
0 0 CL Path Identification
76 Bytes
0 1 Idle Signal Identification
76 Bytes
1 0 Test Signal Identification
76 Bytes
1 1 ITU-T Path Identification
82 Bytes
Bit 3 - RxCR (Command/Response) Type
This Read Only bit field indicates the value of the C/R
(Command/Response) bit-field of the latest received
LAPD Message.
Bit 2 - Rx FCS (Frame Check Sequence) Error
This Read-Only bit-field indicates whether or not the
LAPD Receiver has detected a Frame Check Se-
quence (FCS) error in the most recently received
LAPD Message Frame. A "0" in this bit-field indicates
that the FCS for the latest received LAPD Message
Frame is correct. A "1" in this bit-field indicates that
the FCS for the latest received LAPD Message Frame
is incorrect.
NOTE: For more information on the LAPD Receiver, please
see Section 3.3.3.2.
Bit 1 - End Of Message
This Read-Only bit-field indicates whether or not the
LAPD Receiver has completed its reception of the lat-
est incoming LAPD Message frame. The local µP
can poll the progress of the LAPD Receiver by peri-
odically reading this bit-field.
A "0" in this bit-field indicates that the LAPD Receiver
is still receiving the latest message from the remote
LAPD Transmitter. A "1" in this bit-field indicates that
the LAPD Receiver has finished receiving the com-
plete LAPD Message Frame.
Bit 0 - Flag Present
This Read-Only bit-field indicates whether or not the
LAPD Receiver has detected the occurrence of the
Flag Sequence byte (0x7E) within the inbound LAPD
channel (e.g., the DL bits in DS3 applications). A "0"
in this bit-field indicates that the LAPD Receiver does
not detect the occurrence of the Flag Sequence byte.
A "1" in this bit-field indicates that the LAPD Receiver
does detect the occurrence of the Flag Sequence
byte.
NOTE: For more information on the LAPD Receiver, please
see Section 3.3.3.2.
2.4.3 Receive E3 Framer Configuration Regis-
ters (ITU-T G.832)
2.4.3.1 Receive E3 Configuration & Status
Register 1 (E3, ITU-T G.832)
75