AR# 66921

Description

Solution

For JESD204 systems, to achieve SYNC all lanes must have achieved code group sync (CGS).

Once CGS has been achieved, the SYNC pin can go high.

• For Subclass 0, this will be immediately.
• For Subclass 1, this will be on the next LMFC boundary (SYSREF must have been supplied to start the LMFC counter)
• For Subclass 2, this will be on the next LMFC boundary (where end of reset started the LMFC counter)

To achieve CGS, a lane must see 0xBC (with charisk set) and there must be no errors (no not in table nor disparity errors).

Once CGS is achieved, the core stays in CGS unless 4 successive invalid octets are received (unexpected K-character, not in table error, or disparity error).

Achieving SYNC does not depend on any link parameters, other than line rate and active lanes.

Once in SYNC, there are 3 main reasons a system may fall out of sync (requesting a resync):

1. CGS is lost, as described above, on any lane
2. An incorrect transition from 0xBC to the start of ILA is detected
3. Misalignment in the received data is detected. This means alignment codes in the data are detected at unexpected positions.
   A resync will be triggered when 8 successive multiframe alignment characters are detected in unexpected places (not at the end of a multiframe).

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