The change in the relative delay through the FPGA for the DQS and DQ is monitored in the XPHY and adjustments are made to the delays to account for the change in resolution of the delay elements. The change in the delays are recorded in the XSDB as shown in following table.
| XSDB Reg | Usage | Signal Description |
|---|---|---|
| VTTRACK_RLDLYQTR_NIBBLE* | One per nibble | QTR position last read during BISC VT Tracking. |
| VTTRACK_RLDLYQTR_MAX_NIBBLE* | One per nibble | Maximum QTR value found during BISC VT Tracking. |
| VTTRACK_RLDLYQTR_MIN_NIBBLE* | One per nibble | Minimum QTR value found during BISC VT Tracking. |
| BISC_ALIGN_PQTR_NIBBLE* | One per nibble | Initial 0° offset value provided by BISC at power-up. |
| BISC_ALIGN_NQTR_NIBBLE* | One per nibble | Initial 0° offset value provided by BISC at power-up. |
| BISC_PQTR_NIBBLE* | One per nibble | Initial 90° offset value provided by BISC at power-up. Compute 90° value in taps by taking (BISC_PQTR – BISC_ALIGN_PQTR). To estimate tap resolution take (¼ of the memory clock period)/ (BISC_PQTR – BISC_ALIGN_PQTR). |
| BISC_NQTR_NIBBLE* | One per nibble | Initial 90° offset value provided by BISC at power-up. Compute 90° value in taps by taking (BISC_PQTR – BISC_ALIGN_PQTR). To estimate tap resolution take (¼ of the memory clock period)/ (BISC_PQTR – BISC_ALIGN_PQTR). |
This is a sample of the results for the VT Tracking XSDB debug signals:
VTTRACK_RLDLYQTR_NIBBLE0 int true 0
VTTRACK_RLDLYQTR_NIBBLE1 int true 0
VTTRACK_RLDLYQTR_NIBBLE2 int true 0
VTTRACK_RLDLYQTR_NIBBLE3 int true 0
VTTRACK_RLDLYQTR_NIBBLE4 int true 0
VTTRACK_RLDLYQTR_NIBBLE5 int true 0
VTTRACK_RLDLYQTR_NIBBLE6 int true 0
VTTRACK_RLDLYQTR_NIBBLE7 int true 0
VTTRACK_RLDLYQTR_NIBBLE8 int true 0
VTTRACK_RLDLYQTR_NIBBLE9 int true 0
VTTRACK_RLDLYQTR_NIBBLE10 int true 0
VTTRACK_RLDLYQTR_NIBBLE11 int true 0
VTTRACK_RLDLYQTR_NIBBLE12 int true 0
VTTRACK_RLDLYQTR_NIBBLE13 int true 0
VTTRACK_RLDLYQTR_NIBBLE14 int true 0
VTTRACK_RLDLYQTR_NIBBLE15 int true 0
VTTRACK_RLDLYQTR_NIBBLE16 int true 0
VTTRACK_RLDLYQTR_NIBBLE17 int true 0
VTTRACK_RLDLYQTR_MAX_NIBBLE0 int true 0
VTTRACK_RLDLYQTR_MAX_NIBBLE1 int true 0
VTTRACK_RLDLYQTR_MAX_NIBBLE2 int true 0
VTTRACK_RLDLYQTR_MAX_NIBBLE3 int true 0
VTTRACK_RLDLYQTR_MAX_NIBBLE4 int true 0
VTTRACK_RLDLYQTR_MAX_NIBBLE5 int true 0
VTTRACK_RLDLYQTR_MAX_NIBBLE6 int true 0
VTTRACK_RLDLYQTR_MAX_NIBBLE7 int true 0
VTTRACK_RLDLYQTR_MAX_NIBBLE8 int true 0
VTTRACK_RLDLYQTR_MAX_NIBBLE9 int true 0
VTTRACK_RLDLYQTR_MAX_NIBBLE10 int true 0
VTTRACK_RLDLYQTR_MAX_NIBBLE11 int true 0
VTTRACK_RLDLYQTR_MAX_NIBBLE12 int true 0
VTTRACK_RLDLYQTR_MAX_NIBBLE13 int true 0
VTTRACK_RLDLYQTR_MAX_NIBBLE14 int true 0
VTTRACK_RLDLYQTR_MAX_NIBBLE15 int true 0
VTTRACK_RLDLYQTR_MAX_NIBBLE16 int true 0
VTTRACK_RLDLYQTR_MAX_NIBBLE17 int true 0
VTTRACK_RLDLYQTR_MIN_NIBBLE0 int true 0
VTTRACK_RLDLYQTR_MIN_NIBBLE1 int true 0
VTTRACK_RLDLYQTR_MIN_NIBBLE2 int true 0
VTTRACK_RLDLYQTR_MIN_NIBBLE3 int true 0
VTTRACK_RLDLYQTR_MIN_NIBBLE4 int true 0
VTTRACK_RLDLYQTR_MIN_NIBBLE5 int true 0
VTTRACK_RLDLYQTR_MIN_NIBBLE6 int true 0
VTTRACK_RLDLYQTR_MIN_NIBBLE7 int true 0
VTTRACK_RLDLYQTR_MIN_NIBBLE8 int true 0
VTTRACK_RLDLYQTR_MIN_NIBBLE9 int true 0
VTTRACK_RLDLYQTR_MIN_NIBBLE10 int true 0
VTTRACK_RLDLYQTR_MIN_NIBBLE11 int true 0
VTTRACK_RLDLYQTR_MIN_NIBBLE12 int true 0
VTTRACK_RLDLYQTR_MIN_NIBBLE13 int true 0
VTTRACK_RLDLYQTR_MIN_NIBBLE14 int true 0
VTTRACK_RLDLYQTR_MIN_NIBBLE15 int true 0
VTTRACK_RLDLYQTR_MIN_NIBBLE16 int true 0
VTTRACK_RLDLYQTR_MIN_NIBBLE17 int true 0
BRAM_BISC_PQTR_ALIGN_NIBBLE0 int true 1
BRAM_BISC_PQTR_ALIGN_NIBBLE1 int true 0
BRAM_BISC_PQTR_ALIGN_NIBBLE2 int true 1
BRAM_BISC_PQTR_ALIGN_NIBBLE3 int true 0
BRAM_BISC_PQTR_ALIGN_NIBBLE4 int true 2
BRAM_BISC_PQTR_ALIGN_NIBBLE5 int true 1
BRAM_BISC_PQTR_ALIGN_NIBBLE6 int true 0
BRAM_BISC_PQTR_ALIGN_NIBBLE7 int true 0
BRAM_BISC_PQTR_ALIGN_NIBBLE8 int true 0
BRAM_BISC_PQTR_ALIGN_NIBBLE9 int true 1
BRAM_BISC_PQTR_ALIGN_NIBBLE10 int true 0
BRAM_BISC_PQTR_ALIGN_NIBBLE11 int true 0
BRAM_BISC_PQTR_ALIGN_NIBBLE12 int true 0
BRAM_BISC_PQTR_ALIGN_NIBBLE13 int true 0
BRAM_BISC_PQTR_ALIGN_NIBBLE14 int true 2
BRAM_BISC_PQTR_ALIGN_NIBBLE15 int true 0
BRAM_BISC_PQTR_ALIGN_NIBBLE16 int true 0
BRAM_BISC_PQTR_ALIGN_NIBBLE17 int true 0
BRAM_BISC_NQTR_ALIGN_NIBBLE0 int true 0
BRAM_BISC_NQTR_ALIGN_NIBBLE1 int true 2
BRAM_BISC_NQTR_ALIGN_NIBBLE2 int true 0
BRAM_BISC_NQTR_ALIGN_NIBBLE3 int true 0
BRAM_BISC_NQTR_ALIGN_NIBBLE4 int true 0
BRAM_BISC_NQTR_ALIGN_NIBBLE5 int true 0
BRAM_BISC_NQTR_ALIGN_NIBBLE6 int true 1
BRAM_BISC_NQTR_ALIGN_NIBBLE7 int true 2
BRAM_BISC_NQTR_ALIGN_NIBBLE8 int true 2
BRAM_BISC_NQTR_ALIGN_NIBBLE9 int true 0
BRAM_BISC_NQTR_ALIGN_NIBBLE10 int true 2
BRAM_BISC_NQTR_ALIGN_NIBBLE11 int true 1
BRAM_BISC_NQTR_ALIGN_NIBBLE12 int true 1
BRAM_BISC_NQTR_ALIGN_NIBBLE13 int true 2
BRAM_BISC_NQTR_ALIGN_NIBBLE14 int true 0
BRAM_BISC_NQTR_ALIGN_NIBBLE15 int true 2
BRAM_BISC_NQTR_ALIGN_NIBBLE16 int true 0
BRAM_BISC_NQTR_ALIGN_NIBBLE17 int true 1
BRAM_BISC_PQTR_NIBBLE0 int true 200
BRAM_BISC_PQTR_NIBBLE1 int true 200
BRAM_BISC_PQTR_NIBBLE2 int true 202
BRAM_BISC_PQTR_NIBBLE3 int true 200
BRAM_BISC_PQTR_NIBBLE4 int true 202
BRAM_BISC_PQTR_NIBBLE5 int true 201
BRAM_BISC_PQTR_NIBBLE6 int true 200
BRAM_BISC_PQTR_NIBBLE7 int true 198
BRAM_BISC_PQTR_NIBBLE8 int true 199
BRAM_BISC_PQTR_NIBBLE9 int true 200
BRAM_BISC_PQTR_NIBBLE10 int true 200
BRAM_BISC_PQTR_NIBBLE11 int true 201
BRAM_BISC_PQTR_NIBBLE12 int true 200
BRAM_BISC_PQTR_NIBBLE13 int true 200
BRAM_BISC_PQTR_NIBBLE14 int true 201
BRAM_BISC_PQTR_NIBBLE15 int true 197
BRAM_BISC_PQTR_NIBBLE16 int true 201
BRAM_BISC_NQTR_NIBBLE0 int true 200
BRAM_BISC_NQTR_NIBBLE1 int true 197
BRAM_BISC_NQTR_NIBBLE2 int true 201
BRAM_BISC_NQTR_NIBBLE3 int true 202
BRAM_BISC_NQTR_NIBBLE4 int true 202
BRAM_BISC_NQTR_NIBBLE5 int true 201
BRAM_BISC_NQTR_NIBBLE6 int true 200
BRAM_BISC_NQTR_NIBBLE7 int true 201
BRAM_BISC_NQTR_NIBBLE8 int true 202
BRAM_BISC_NQTR_NIBBLE9 int true 202
BRAM_BISC_NQTR_NIBBLE10 int true 204
BRAM_BISC_NQTR_NIBBLE11 int true 204
BRAM_BISC_NQTR_NIBBLE12 int true 201
BRAM_BISC_NQTR_NIBBLE13 int true 205
BRAM_BISC_NQTR_NIBBLE14 int true 202
BRAM_BISC_NQTR_NIBBLE15 int true 202
BRAM_BISC_NQTR_NIBBLE16 int true 201
BRAM_BISC_NQTR_NIBBLE17 int true 202