[Milkymist-devel] Memory test fail on ML-401

[Sébastien Bourdeauducq]

On Sunday 19 July 2009 15.04.34 Sébastien Bourdeauducq wrote:
> * Large clock skew due to routing delays (but you'd need a 2.5ns skew to
> explain this phenomenon, which is a lot)

After opening the design with FPGA Editor (and copying the NGD file somewhere 
else because it fails if you have too many subfolders[1]), routing delays are:

    2.952ns - comp.pin "sdram_dqs<0>.O", site.pin "D25.O"
    2.518ns - comp.pin "sdram_dqs<1>.O", site.pin "G18.O"
    2.781ns - comp.pin "sdram_dqs<2>.O", site.pin "G17.O"
    3.214ns - comp.pin "sdram_dqs<3>.O", site.pin "D26.O"
    0.169ns - comp.pin "ddram/clkgen_dqs.CLKFB", site.pin "DCM_ADV_X0Y4.CLKFB"
     driver - comp.pin "ddram/clkgen_dqs.CLK0", site.pin "DCM_ADV_X0Y4.CLK0"

So this is the explanation.

Sébastien

[1] http://lekernel.net/blog/?p=438