Open Collector on per-pin basis [not an issue, passing along a message]

[peterzieba]

Re:
cpu030/cpld-files/SYSCTL.pld
"* If someone can clue me in on how to use the Open_collector property

• on a per-pin basis, that would be s00000p3r!
  */"

Should just be:
PROPERTY ATMEL { open_collector=IACK,CI };

Confirm by looking at the .fit output from the fitter and make sure you see it acknowlged. Should see something like:
Open_collector = IACK,CI,

Then later in the .fit file you should see:

SO Pin Options Field = Summary of Allocations.
||
||_OpenCol [o,-]      ==  o = Open Collector enabled, - CMOS drive.
|
|__Slew [s,f]         ==  Output Slew/Drive rate, s = slow/low, f = fast/hi drive.

The last letter of the last column for a given macrocell should be have an 'o' instead of the usual '-'

Cool project.

Cheers

[thorpej]

Oh, thanks for the tip! I'm now using yosys + the Atmel fitter, so I think I can adapt this using some arguments to the fitter tool. But it would be nice to confirm that it will do what I expect, which is:

If set the signal to 0, it drives the pin to 0 -- set the signal to 1 and it floats the pin.

[peterzieba]

That is my understanding, yes, but probably makes sense to verify it.

Someday I hope to pick up again making some kind of sensible workflow to avoid using WinSim so that things like that can be verified more easily.

[thorpej]

Ok, I have some PLCC 1504s that I could verify this with easily enough. Thanks!