Altmemddr_sysclk

[Altera_Forum]

Dear all, 

 We all know we use altmemddr_sysclk a lot in SOPC builder for DDR SDRAM controller and to drive other SOPC module.  There are so many clock, anyone can summarize their relationships? We never see a pin for altmemddr_sysclk, it seems an internal clock.   what is the relationship between altmemddr_sysclk and mem_clk?  and for altmemddr_sysclk and altmemddr_phy_clk_out, are they the same clock?  Thank you very much!

[Altera_Forum]

Here you go: 

http://www.altera.com/literature/hb/external-memory/emi_ddr_ug.pdf  The sysclk is the clock intended to be used for your parallel domain interface to the DDR SDRAM controller. This clock may be either 1X or 2X the phy clock depending on whether you've selected a Full-rate or Half-rate interface. The mem_clk (and mem_clk_n) signals are the actual physical layer clock(s) that connect to the DDR component(s) (or module(s)).  Jake