Each DQS is adjusted to be aligned with CK. The memory is placed
in read levelling calibration mode, so the DQ values returned are the CK being sampled
by the DQS at the memory. DQS is then adjusted to align with the CK at the
memory.
This is accomplished as follows:
- Search for a stable 1 on the DQ by incrementing coarse taps.
- Decrement coarse taps to find a stable 0.
- Use fine taps to center on the noise region.
| Register Name | Quantity | Description |
|---|---|---|
| Fx_WRLVL_CRSE_STG1 | Rank and byte | Is this the Coarse Tap setting after finding the stable 1 |
| Fx_WRLVL_OFFSET | Rank and byte | 90 degree offset in fine taps |
| Fx_WRLVL_CRSE_FINAL | Rank and byte | Stable 0 in coarse taps |
| Fx_WRLVL_NOISE_FCRSE | Rank and byte | Output delay value for valid-to-noise |
| Fx_WRLVL_FINE_LEFT | Rank and byte | The Fine Tap setting for the left side of the noise window |
| Fx_WRLVL_FINE_RIGHT | Rank and byte | The Fine Tap setting for the right side of the noise window |
| Fx_WRLVL_FINE_FINAL | Rank and byte | The final Fine Tap setting |