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Zynq-7000 AP SoC Technical Reference Manual www.xilinx.com 1639
UG585 (v1.11) September 27, 2016
Appendix B: Register Details
START_CAL_DLL 1 wo 0x0 This register creates a pulse that is first
synchronised into the ddr_clk domain and then
directly drives the co_gs_dll_calib input into the
DDR controller. This signal is a command that
indicates to the controller to issue a dll_calib to the
DRAM. This signal should pulse for 1
ddrc_core_clk clock cycle to request a dll_calib to
be issued. This is only required if the DDR
controller register reg_ddrc_dis_dll_calib is 1. If
reg_ddrc_dis_dll_calib is 0, the controller will
automatically issue DLL Calibs.
0: Do nothing.
1: Start DLL calibration command.
A read of this register returns zero.
START_CAL_SHORT 0 wo 0x0 This register creates a pulse that is first
synchronized into the ddr_clk domain and then
directly drives the co_gs_zq_calib_short input
into the DDR controller. This is required to pulse
for 1 clock to issue ZQ Calibration Short
Command to the DDR. There should be a
minimum of 512 clks gap between 2 ZQ Calib
Short commands from the core. If DDR controller
register reg_ddrc_dis_auto_zq=0, asserting
co_gs_zq_calib_short is not required, as this will
be done automatically. If
reg_ddrc_dis_auto_zq=1, then the core logic is
required to assert co_gs_zq_calib_short
periodically to update DDR3 ZQ calibration.
0: Do nothing.
1: Start ZQ calibration short command.
A read of this register returns zero.
Field Name Bits Type Reset Value Description