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IDT82V2108
T1 / E1 / J1 OCTAL FRAMER
Functional Description
24
March 5, 2009
3.6
BIT-ORIENTED MESSAGE RECEIVER (RBOM) -
T1/J1 ONLY
The Bit Oriented Message (BOM) can only be received in the ESF
format in T1/J1 mode. The standard of BOM is defined in ANSI T1.403
and in TR-TSY-000194. This block of each framer operates indepen-
dently.
The BOM pattern is ‘111111110XXXXXX0’ which occupies the DL of
the F-bit in the ESF format (refer to
Table 4). The six ‘X’s represent the
message. The BOM is declared only when the pattern is matched and
the received message is identical 4 out of 5 times or 8 out of 10 times.
The identification time is determined by the AVC (b1, T1/J1-02AH). After
the BOM is declared, the BOM is loaded into the BOC[5:0] (b5~0, T1/J1-
02BH). However, the BOM does not include all ones code in both T1 and
J1 mode.
When the BOM is converted into non-BOM, the received data will
be idle code. The pattern of the idle code is ‘FFFF’ in T1 mode and
‘FF7E’ in J1 mode. When the received data is 4 out of 5 times or 8 out of
10 times identical with the pattern, the idle code is declared. The identifi-
cation time is determined by the AVC (b1, T1/J1-02AH).
There are two interrupt sources in this block. When the BOM is
declared, the BOCI (b6, T1/J1-02BH) will be set. When the idle code is
declared, the IDLEI (b7, T1/J1-02BH) will be set. If the BOCE (b0, T1/
J1-02AH) and IDLE (b2, T1/J1-02AH) are set to ‘1’ respectively, the cor-
responding condition will cause an interrupt on the INT pin.
3.7
INBAND LOOPBACK CODE DETECTOR (IBCD) -
T1/J1 ONLY
The Inband Loopback Code Detector can track loopback activate/
deactivate codes only in framed or unframed T1/J1 data stream. The
Inband Loopback Code Detector of each framer operates independently.
The received data stream is compared with the target activate/
deactivate code whose length and the content are programmed in the
ASEL[1:0] (b1~0, T1/J1-03CH) / DSEL[1:0] (b3~2, T1/J1-03CH) and the
ACT[7:0] (b7~0, T1/J1-03EH) / DACT[7:0] (b7~0, T1/J1-03FH) respec-
tively. In framed mode, the F-bit can be chosen by the IBCD_IDLE (b5,
T1/J1-000H) to compare with the target activate/deactivate code or not.
In unframed mode, all 193 bits are compared with the target activate/
deactivate code. If the received data stream matches the target activate
or deactivate code and repeats for a 39.8 ms period, the LBACP (b7, T1/
J1-03DH) or LBDCP (b6, T1/J1-03DH) will indicate the appearance of
the corresponding code. 2, 20 or 200 bit-error tolerance within each 39.8
ms period is permitted by setting the IBCD_ERR[1:0] (b5~4, T1/J1-
03CH). However, even if the F-bit is compared, whether it is matched or
not, the result will not cause bit errors, that is, the comparison result of
the F-bit is passed over.
When the received data stream matches the target activate/deacti-
vate code and repeats for 5.1 sec, the LBA (b1, T1/J1-03DH) / LBD (b0,
T1/J1-03DH) will indicate the detection of the inband loopback code.
The code sequences detection and timing is compatible with the specifi-
cations in T1.403, TA-TSY-000312 and TR-TSY-000303.
The status changes of the activate or deactivate code are the inter-
rupt sources in the IBCD block. That is, when the value in the Status
Register (LBA [b1, T1/J1-03DH] or LBD [b0, T1/J1-03DH]) changes, its
corresponding Interrupt Indication Register (LBAI [b3, T1/J1-03DH] or
LBDI [b2, T1/J1-03DH]) will be logic 1. A logic 1 on the Interrupt Indica-
tion Register will cause an interrupt on the INT pin if the corresponding
Interrupt Enable Register (LBAE [b5, T1/J1-03DH] or LBDE [b4, T1/J1-
03DH]) is logic 1.