DS92UT16 Datasheet, PDF (28/111 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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FRAME DELINEATION
Once the system has achieved TC delineation, the Frame delineation process can begin. The Frame delineation
process is achieved by checking for correct HEC’s with the added coset x⁶ + x⁴ + x² + 1. This added coset
differentiates ‘Start of Frame’ TC HEC’s from normal TC HEC’s. Only the HEC of TC0 has this added coset.
This is the standard coset which may be added to all HEC’s (CDIS bit in the LKSC register in LINK STATUS
AND CONTROL—0x08 LKSC). If the coset is already added to all HEC’s, then it is added again to the HEC of
TC0. This ensures that the HEC of TC0 can always be differentiated from that of other TC’s.
The Frame delineation state diagram is shown in Figure 13.
Figure 13. State Diagram for Frame Delineation
F_HUNT—On reset, the Frame delineation state machine starts in the F_HUNT state and Frame delineation has
not been achieved. Each received HEC is monitored to determine if it has the added coset and is therefore the
Start Of Frame (SOF) HEC. When a single correct SOF HEC is detected, the state machine enters the
F_PRESYNC state.
F_PRESYNC—In the F_PRESYNC state if a correct SOF HEC is found SIGMA consecutive times the state
machine moves to the F_SYNC state and the system is said to have achieved Frame delineation. If an errored
SOF HEC is detected during the F_PRESYNC state the state machine moves back to the F_HUNT state.
F_SYNC—In the F_SYNC state, Frame delineation will be assumed to be lost if an erred SOF HEC is obtained
on MU consecutive occasions. The state machine will move back to the F_HUNT state.
The values of SIGMA and MU are programmable independently for Port A and Port B. They are contained in the
RAFDT and RBFDT registers (see RECEIVE PORT A FRAME DELINEATION THRESHOLDS—0x41 RAFDT
and RECEIVE PORT B FRAME DELINEATION THRESHOLDS—0x81 RBFDT).
On reset, SIGMA = 8 and MU = 7.
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