User manual

Table Of Contents
Zynq-7000 AP SoC Technical Reference Manual www.xilinx.com 318
UG585 (v1.11) September 27, 2016
Chapter 10: DDR Memory Controller
Table 10-9 provides summary of register values involved in manual training. All values are in units of
1/256 of a clock cycles (256 units = 1 clock cycle, 8 units = 1/32 of a clock cycle).
10.6.11 DRAM Write Latency Restriction
Note that the minimum DRAM write latency supported is 3. This implies that the minimum CAS
latency is 4.
10.7 Register Overview
In general, the DDRC registers are static and can only be changed while the DDRC is in reset.
However, there is a set of registers labeled as dynamic in their description that can be modified at
anytime.
10.7.1 DDRI
Table 10-10 shows an overview of DDRI registers. There are no dynamic bit fields in the DDRI
registers.
Table 10-9: Manual Training Register Summary
Parameter Register Nominal Value
Minimum
Suggested
Search Range
1 Write DQS delay/write leveling reg_phy_wr_dqs_slave_ratio[9:0] DQS to DCLK delay 0 -256
2 Write data delay/write data eye
adjustment
reg_phy_wr_data_slave_ratio[9:0] DQS to DCLK delay + 64 64-320
3 Read DQS gate
delay/read DQS gate training
reg_phy_fifo_we_slave_ratio[10:0] 2 * board delay 0-512
4 Read data to DQS delay/read
data eye training
reg_phy_rd_dqs_slave_ratio[9:0] 53, placing the DQS edges in
the middle of the data eye
0 - 104
(1)
5 Control reg_phy_ctrl_slave_ratio[9:0] 128 (64 for LPDDR2) 64-192
(32-96 for
LPDDR2)
Notes:
1. Parameter 4 is an offset value relative to parameter 3.