Zynq-7000 AP SoC and 7 Series FPGAs MIS v4.1
249
UG586 November 30, 2016
Chapter 1:
DDR3 and DDR2 SDRAM Memory Interface Solution
Debugging MPR Read Leveling Failures – DDR3 Only (dbg_rdlvl_err[1] = 1)
Calibration Overview
At this stage of calibration, the write
DQS
is not centered in the write
DQ
window, nor is the
read
DQS
centered in the read
DQ
window. The DDR3 Multi-Purpose Register (MPR) is used
to center the read
DQS
in the read
DQ
window. The MPR has a pre-defined “01010101” or
“10101010” pattern that is read back during this stage of calibration. The read
DQS
centering is required for the next stage of calibration, OCLKDELAYED calibration.
X-Ref Target - Figure 1-100
Figure 1-100:
Trigger = dbg_wrcal_start
X-Ref Target - Figure 1-101
Figure 1-101:
Trigger = init_calib_complete