The final stage of DQS read centering that is
completed before normal operation repeats the steps performed during MPR DQS read
centering but with a difficult/complex data pattern. The purpose of using a complex
pattern is to stress the system for SI effects such as ISI and noise while calculating
the read DQS center position. This ensures that the read center position can reliably
capture data with margin in a true system.
This is accomplished as follows:
- Reset PQTR and NQTR delays to 0 and verify that data is being properly read.
- Delay the DQ/DBI until the noise region is found. Use short read bursts until noise region is found, then use long reads for accurate edge detection.
- Delay the clock strobe to return to the valid region, continue until the noise region on the other side is found. Use short read bursts until noise region is found, then use long reads for accurate edge detection.
- Center the strobe in the valid region.
Register Name | Quantity | Description |
---|---|---|
Fx_RDCMPLX_IDELAY_OFFSET | Nibble | Idelay at left edge. (in noise region) |
Fx_RDCMPLX_PQTR_LEFT_SHORT | Nibble | Tap value for left side of window with short complex pattern, rising edge (noise to valid) |
Fx_RDCMPLX_NQTR_LEFT_SHORT | Nibble | Tap value for left side of window with short complex pattern, falling edge (noise to valid) |
Fx_RDCMPLX_PQTR_LEFT | Nibble | Tap value for left side of window with long complex pattern, rising edge (noise to valid) |
Fx_RDCMPLX_NQTR_LEFT | Nibble | Tap value for left side of window with long complex pattern, falling edge (noise to valid) |
Fx_RDCMPLX_PQTR_RIGHT_SHORT_FCRSE | Nibble | Short pattern with 10-increment steps for right edge, rising edge (valid to noise) |
Fx_RDCMPLX_NQTR_RIGHT_SHORT_FCRSE | Nibble | Short pattern with 10-increment steps for right edge, falling edge (valid to noise) |
Fx_RDCMPLX_PQTR_RIGHT_SHORT | Nibble | Tap value for right side of window with short complex pattern, rising edge (valid to noise) |
Fx_RDCMPLX_NQTR_RIGHT_SHORT | Nibble | Tap value for right side of window with short complex pattern, falling edge (valid to noise) |
Fx_RDCMPLX_PQTR_RIGHT | Nibble | Tap value for right side of window with long complex pattern, rising edge (valid to noise) |
Fx_RDCMPLX_NQTR_RIGHT | Nibble | Tap value for right side of window with long complex pattern, falling edge (valid to noise) |
Fx_RDCMPLX_PQTR_FINAL | Nibble | Final centered tap value for PQTR |
Fx_RDCMPLX_NQTR_FINAL | Nibble | Final centered tap value for NQTR |