Description

The following error occurs when I run a DRC check for my Base System Builder MIG design:

"ERROR:EDK - DDR3_SDRAM (axi_7series_ddrx) - The clock frequencies are not correct or are not correctly specified for the input clock ports.   The specification 'Frequency of port "clk"' (133333333) * 'Parameter "C_NCK_PER_CLK"'(4)  == 'Frequency of port "mem_refclk"' (533333333) has failed."

Looking at clock frequency:
    clk = 133333333
    mem_refclk = 533333333
It is sure "mem_refclk = clk * 4".

When I set as below, I see no errors:
    clk = 125000000
    mem_refclk = 500000000

How can I work around this error? The TCL constraint cannot round properly for this use-case.

C:\Xilinx\14.4\ISE_DS\EDK\hw\XilinxProcessorIPLib\pcores\axi_7series_ddrx_v1_07_a\data\axi_7series_ddrx_v2_1_0.tcl

Solution

Please change the output clock that sets the mem_refclk_freq's value, which is C_CLKOUT1_FREQ in this case.

BEGIN clock_generator
 PARAMETER INSTANCE = clock_generator_0
 PARAMETER HW_VER = 4.03.a
 PARAMETER C_CLKIN_FREQ = 200000000
 PARAMETER C_CLKOUT0_FREQ = 533333333
 PARAMETER C_CLKOUT0_PHASE = 337.5
 PARAMETER C_CLKOUT0_GROUP = PLLE0
 PARAMETER C_CLKOUT0_BUF = FALSE
 PARAMETER C_CLKOUT1_FREQ = 533333332    <------ change this

The reason this DRC cannot catch this is it is not able to catch repeating digits.