Question Setup Timing units of measure ?

[Soulkeeper]

Can someone confirm what unit of measure is used in the gigabyte bios for "CAD Bus Setup Timing" AddrCmdSetup, CsOdtSetup, and CkeSetup ?
I figure there are atleast 2 possibilities: fractions of a clock(1/64th of 1/4 or 1/2 cycle) or picoseconds 1 to 63ps.
I'm leaning towards fractions of 1/4 clk. The values can be entered in the range of AUTO or 1-63

My testing seems to indicate that there is a window of what works and don't work.
AUTO won't post, 1-6 stable, 7-13 post but unstable, 14-47 won't post, ~50-63 stable

Thanks.

 

[Soulkeeper]

Ok, they appear to be fractions of 1T ie: half a clock cycle.
If you need a setup time greater than 64 then you need 2T timing.
Setting a low setup time might work, it would essentially be a 1T phase shift. This would explain the "window" of values that don't work.
In this case the potential setup time might be something like 65-70 with a very low hold time (likely not 100% stable using such a hack, should be 2T instead). Or, worded another way, the hold time is a few fractions of a clock Tick into the next Tick and takes the entire Tick to setup.

This is of course all comparing the differential clock pair crossings (ie: rising/falling edges) to the address/cmd, cs/odt, and cke signals. address/cmd being the worst due to a shared bus connecting a fly-back bus on each chipselect/rank.
cs/odt and cke have a single bus directly to each fly-back bus on each chipselect/rank.