The following error occurs and is related to MMCM connectivity during MAP:
" ERROR:Place:1164 - The clock source component "DDR2SODIMMGen.DDR2/DDRBkg/u_mem_intfc/phy_top0/u_phy_read/mb_rdclk_gen_inst.u_phy_rdclk_gen/
u_mmcm_clk_base" and a load component
"DDR2SODIMMGen.DDR2/DDRBkg/u_mem_intfc/phy_top0/u_phy_read/mb_rdclk_gen_inst.u_phy_rdclk_gen/
gen_ck_cpt[2].u_oserdes_cpt" have been constrained or locked on two locations that are too far from each other, which cause the clock signal unroutable."
My design looks fine. Is this error correct?
There are some known cases where a check of the validity of MMCM placement has resulted in a false positive. For ISE version 11.2, an environment variable is being provided to bypass the error and continue processing as both a work-around for false positives for this error, and also to allow examination of the placed design in FPGA Editor in the case of a valid error. If the router is able to successfully route the design after the error is bypassed, then the error can be considered to have been false. Two cases of false errors are under investigation for a fix in ISE version 11.3.
To disable the Place:1164 error:
Linux
setenv XIL_PLACE_DISABLE_MMCM_CLOCK_CHECK 1
Windows
SET XIL_PLACE_DISABLE_MMCM_CLOCK_CHECK=1
For general information about setting ISE environment variables, see (Xilinx Answer 11630).