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____________________________________________________ DS34T101, DS34T102, DS34T104, DS34T108
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Table 10-57. Registers Related to T1 In-Band Loop Code Detection
Register Field
Description
Functions
Page
Rx In-Band Code Control Register
Rx up code and down code length
Rx Up Code Definition Register 1
Rx up code definition
Rx Up Code Definition Register 1
Rx up code definition
Rx Down Code Definition Register 1
Rx down code definition
Rx Down Code Definition Register 2
Rx down code definition
Rx In-Band Spare Control Register
Rx spare code length
Rx Spare Code Register 1
Rx spare code register
Rx Spare Code Register 1
Rx spare code register
Rx Real-Time Status Register 3
real-time loop/spare code detect bits
Rx Latched Status Register 3
latched loop/spare code detect bits
Rx Interrupt Mask Register 3
interrupt mask bits
10.11.15 G.706 Intermediate CRC-4 Recalculation (E1 Only)
The framer can implement the G.706 CRC-4 recalculation at intermediate path points. When this mode is enabled,
the data stream presented at TSER already has the FAS/NFAS, CRC-4 multiframe alignment word and CRC-4
checksum in timeslot 0. The CPU can modify the Sa bit positions and this change in data content can then be used
to modify the CRC-4 checksum. This modification, however, does not corrupt any error information the original
CRC-4 checksum may contain. In this mode of operation, TSYNC must be configured to multiframe mode
(
TIOCR.TSM=1). The data at TSER must be aligned to the TSYNC signal. If TSYNC is an input then the system
must assert TSYNC aligned at the beginning of the multiframe relative to TSER. If TSYNC is an output, the system
must multiframe-align the data presented to TSER. This mode is enabled when
TCR3.CRC4R=1. Note that the E1
transmitter must already be configured for CRC insertion with
TCR1-E1.TCRC4=1.
Figure 10-65. CRC-4 Recalculate Method
10.11.16 SLC–96 Operation (T1 Only)
In a SLC-96 transmission scheme, the standard Fs bit pattern is robbed to make room for a set of message fields.
The SLC-96 multiframe is made up of six D4 superframes and is therefore 72 frames long. In the 72-frame
SLC–96 multiframe, 36 of the framing bits are the normal Ft pattern and the other 36 bits are divided into alarm,
maintenance, spoiler, and concentrator bits as well as 12 bits of the normal Fs pattern. Additional SLC-96
information can be found in Bellcore document TR-TSY-000008. Registers related to SLC-96 functionality are
shown in the following table.
Table 10-58. Registers Related to SLC96
Register Name
Description
Functions
Page
Transmit FDL Register
Tx SLC-96 messages in Ft/Fs bits
Receive SLC 96 Data Link Registers 1 to 3
Tx SLC-96 overhead values
Transmit Control Register 2
Tx SLC-96 enable control bit
DATA
TSER
XOR
CRC-4
CALCULATOR
EXTRACT
OLD CRC-4
CODE
INSERT
NEW CRC-4
CODE
MODIFY
Sa BIT
POSITIONS
NEW Sa BIT
+
POS/NEG
TO LIU