Re: Boosting STFM: 16MHz bus, 64MHz Shifter
Posted: Wed Mar 07, 2018 12:50 pm
can you add some delay to the cpu clock and try ?
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... but why not assume that a drive suddenly went bad and then another drive also had gone bad?
Ah, no, there is a difference. With the F161, all _derived_ clocks are synced on the falling edge, on the rising edge of the F161 itself. That one I clocked with the same clock as the MMU got. I.e, with the F161 all downstream clocks were skewed compared to the MMU.
Currently I have GLUE offset from CPU similar to what I did with the F161 to get 200% RAM boost. Will test with all in sync as well.
I've had issues that once I "split" the 8mhz clock and ran it via a GAL instead, the GLUE screws up... The 8mhz line (at least on the boards I work with) depend on the "load" of the GLUE etc. So I actually resorted to adding 50pF onto the 8Mhz line to "load" it like the GLUE did to clamp down on some ringing.troed wrote: ↑Wed Mar 07, 2018 5:58 pm However, I think at the moment it's much more stable with the LA connected to all clocks than without. I'm only using 33 Ohm resistors in series, I'm thinking to up that to 100. Or add some capacitance. Not sure why the GAL output has ringing clocks ... I think it's finally time to test out my scope
IIRC when I tried it, it didn't work. I tried to buffer the 8MHz clock via a GAL, got about 10ns delay first IO chain, then I linked IO pins in series to gain a bank of 10ns per "gate" and it didn't work. Delays were always 10ns total even though I was going in and out of 8 IO pints. I think there might have been 1ns extra delay, but I didn't spend much time investigating it. I could have messed something up..