DS92UT16 Datasheet, PDF (26/111 Pages) Texas Instruments – DS92UT16TUF UTOPIA-LVDS Bridge for 1.6 Gbps Bi-directional Data Transfers

DS92UT16
OBSOLETE
SNOS992E – JANUARY 2002 – REVISED APRIL 2013
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NOTE
The devices at both ends of the LVDS link must be configured with the same values for
the PDUCFG, USPAL, and USPAM registers for correct operation.
NOTE
When configuration of both ends of the link is complete then CTI must not be disabled for
at least two PDU transport times (i.e. the length of time it takes to transport two PDUs
over the LVDS link). This “CTI disable hold-off period” allows all PDUs of the old
configuration to be received and discarded correctly. If this hold-off period is not respected
then an idle cell PDU of the old PDU configuration may arrive at a device programmed
with the new PDU configuration and incorrectly be interpreted as a valid cell.
NOTE
Any change in the PDU configuration which changes the byte location of the TC HEC byte
will cause the far end device to fall out of TC delineation. See Figure 6.
Cell/Frame Delineation and Descrambler Operation
Each of the two Transmission Convergence Sub-Layer (TCS) DisAssemblers receives 16-bit data from the
associated LVDS receive section. The TCS DisAssembler must first find the Transport Container (TC)
boundaries, then the data can be descrambled and the Frame boundaries found. Once this has been achieved
the received data can be disassembled.
After achieving TC delineation and the Descrambler locking, then the cell data within each TC is valid and can be
passed to the MTB. If TC delineation is lost, or the Descrambler is not locked, then cell data is invalid and is not
passed to the MTB.
Frame delineation must be achieved before the bytes of the F Channel are considered valid. The F Channel
consists of the ECC, Flow Control, BIP, Remote Alarm and Signaling and Link Label bytes (see F Channel Byte
Usage Within the Frame). If Frame delineation is lost then
• the received ECC bytes are considered invalid and are assumed to retain the last valid values received
• the Flow Control bytes are considered invalid and are assumed to be all ones, i.e. ‘halt’ all ports
• the Remote Alarm and Signaling byte is considered invalid and is assumed to retain the last valid value
received
• and the Link Label byte is considered invalid and is assumed to retain the last valid value received.
TC and Frame delineation is achieved using the HEC bytes of the TC’s. The HEC bytes are not scrambled.
The Descrambler is loaded with the Scrambler sequence on start-up to achieve lock. The operation of these
blocks is described below.
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