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Zynq-7000 AP SoC Technical Reference Manual www.xilinx.com 846
UG585 (v1.11) September 27, 2016
Appendix B: Register Details
Register DRAM_param_reg1 Details
Register (ddrc) DRAM_param_reg2
Field Name Bits Type Reset Value Description
reg_ddrc_t_cke 31:28 rw 0x3 Minimum number of cycles of CKE HIGH/LOW
during power down and self refresh.
DDR2 and DDR3: Set this to tCKE value.
LPDDR2: Set this to the larger of tCKE or tCKESR.
Unit: clocks.
reg_ddrc_t_ras_min 26:22 rw 0x14 tRAS(min) - Minimum time between activate and
precharge to the same bank.
Unit: clocks
DRAM related.
Default value is set for DDR3.
reg_ddrc_t_ras_max 21:16 rw 0x1B tRAS(max) - Maximum time between activate and
precharge to same bank. Maximum time that a
page can be kept open (spec is 70 us). If this is zero
then the page is closed after each transaction.
Unit: Multiples of 1024 clocks
DRAM related.
reg_ddrc_t_faw 15:10 rw 0x12 tFAW - At most 4 banks must be activated in a
rolling window of tFAW cycles. Unit: clocks.
DRAM Related.
reg_ddrc_powerdown_
to_x32
9:5 rw 0x6 After this many clocks of NOP or DESELECT the
controller will put the DRAM into power down.
This must be enabled in the Master Control
Register. Unit: Multiples of 32 clocks.
reg_ddrc_wr2pre 4:0 rw 0x19 Minimum time between write and precharge to
same bank
DDR and DDR3: WL + BL/2 + tWR
LPDDR2: WL + BL/2 + tWR + 1
Unit: Clocks
Where,
WL: write latency.
BL: burst length. This must match the value
programmed in the BL bit of the mode register to
the DRAM. BST is not supported at present.
tWR: write recovery time. This comes directly
from the DRAM specs.
Name DRAM_param_reg2
Relative Address 0x0000001C
Absolute Address 0xF800601C