22.214.171.124. Frame Alignment
The frame alignment is monitored through the alignment character /F/. The transmitter inserts this character at the end of frame. The /A/ character indicates the end of multiframe. The character replacement algorithm depends on whether scrambling is enabled or disabled, regardless of the csr_lane_sync_en register setting.
The alignment detection process:
- If two successive valid alignment characters are detected in the same position other than the assumed end of frame—without receiving a valid or invalid alignment character at the expected position between two alignment characters—the receiver realigns its frame to the new position of the received alignment characters.
- If lane realignment can result in frame alignment error, the receiver issues an error.
In the JESD204B RX IP core, the same flexible buffer is used for frame and lane alignment. Lane realignment gives a correct frame alignment because lane alignment character doubles as a frame alignment character. A frame realignment can cause an incorrect lane alignment or link latency. The course of action is for the RX to request for reinitialization through SYNC_N. 22
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