DS92UT16 Datasheet, PDF (27/111 Pages) Texas Instruments – DS92UT16TUF UTOPIA-LVDS Bridge for 1.6 Gbps Bi-directional Data Transfers

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DS92UT16
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SNOS992E – JANUARY 2002 – REVISED APRIL 2013
TRANSPORT CONTAINER DELINEATION
At the receive end of the LVDS link, the data will appear as a stream with no indication of Transport Container
(TC) or frame boundaries. TC delineation is achieved by finding correct HEC’s on the incoming data stream. The
TC delineation state diagram is shown in Figure 12.
Figure 12. State Diagram for TC Delineation
C_HUNT—On reset, the TC delineation state machine starts in the C_HUNT state and TC delineation has not
been achieved. In the C_HUNT state, a HEC is calculated word by word on a data stream equal in length to the
TC Header and compared against the next received byte. The length of the TC header is derived from the
PDUCFG register (see PDU CONFIGURATION—0x05 PDUCFG). This process is repeated until a correct HEC
is detected. When a single correct HEC has been detected the state machine moves into the C_PRESYNC state.
Note that depending on the length of the TC and the length of the TC Header it may be necessary to word slip
after a predefined number of HEC calculations in order to obtain a correct HEC.
C_PRESYNC—In C_PRESYNC, if a correct HEC is found DELTA consecutive times then the state machine
moves to the C_SYNC state and the system has achieved TC delineation. If an erred HEC is detected during the
C_PRESYNC state, the process moves back to the C_HUNT state.
C_SYNC—In the C_SYNC state, TC delineation is assumed to be lost if an erred HEC is obtained on ALPHA
consecutive occasions. The state machine will move back to the C_HUNT state.
The values of DELTA and ALPHA are programmable independently for Port A and Port B. They are contained in
the RACDT and RBCDT registers (see RECEIVE PORT A CELL DELINEATION THRESHOLDS—0x40 RACDT
and RECEIVE PORT B CELL DELINEATION THRESHOLDS—0x80 RBCDT). On reset, DELTA = 8 and ALPHA
= 7.
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