Does anybody know what happened to the docs at https://antmicro-skywater-pdk-docs.readthedocs.io/ ? I get a 404 now.

I noticed the same thing on the weekend also when looking up the GPIO datasheets.

@Matt Liberty @Andrew Wright Does https://skywater-pdk.readthedocs.io/en/main/ have what you want? I think the

antmicro

version was “unofficial”.

Where would I find the description of a std cell, eg sky130_fd_sc_hd__dfsbp_1 ?

It’s probably not in a very usable format, but what about here?

The ant micro version was much nicer without having to dig through the details

I am attempting to produce an improved online version, but I am having to learn quite a bit of VLSI theory at the same time. So if anyone has some math to compute 'Dynamic Power', 'Intrinsic Delay' and 'Delay Kload' ideally directly from liberty (.lib) file data, if not possible then with SPICE model snippets, I can probably close out stage 1 on this. DRAFT outline of the concept, please DM.

Nice work @dlmiles! Currently the spice file associated with each cell is an extracted netlist generated from the layout. The corresponding cdl file appears to be generated from a schematic editor, but the original data is unavailable as far as I know. It might be helpful to have a xschem schematic with test inputs for each cell. In the variations section under artifacts, what does NETLIST represent?

NETLIST is an artifact/file present in the original Google PDK https://github.com/google/skywater-pdk-libs-sky130_fd_sc_hd/blob/ac7fb61f06e6470b9[…]df7c25268f62fbd7b1/cells/inv/sky130_fd_sc_hd__inv_1.netlist.tsv

There’s test bench for a relatively simple circuit in

caravel/xschem/simple_por_tb.sch

. This is what a xschem schematic file would look like for an inverter (sizes and models may differ)

v {xschem version=3.0.0 file_version=1.2 }
G {}
K {}
V {}
S {}
E {}
N -40 -30 -40 30 {
lab=A}
N -120 -0 -40 0 {
lab=A}
N 0 0 100 -0 {
lab=Y}
C {sky130_fd_pr/nfet3_01v8.sym} 620 260 0 0 {name=M1
L=0.15
W=1
body=GND
nf=1
mult=1
ad="'int((nf+1)/2) * W/nf * 0.29'" 
pd="'2*int((nf+1)/2) * (W/nf + 0.29)'"
as="'int((nf+2)/2) * W/nf * 0.29'" 
ps="'2*int((nf+2)/2) * (W/nf + 0.29)'"
nrd="'0.29 / W'" nrs="'0.29 / W'"
sa=0 sb=0 sd=0
model=nfet_01v8
spiceprefix=X
}
C {sky130_fd_pr/pfet_01v8.sym} -20 -30 0 0 {name=M2
L=0.15
W=1
nf=1
mult=1
ad="'int((nf+1)/2) * W/nf * 0.29'" 
pd="'2*int((nf+1)/2) * (W/nf + 0.29)'"
as="'int((nf+2)/2) * W/nf * 0.29'" 
ps="'2*int((nf+2)/2) * (W/nf + 0.29)'"
nrd="'0.29 / W'" nrs="'0.29 / W'"
sa=0 sb=0 sd=0
model=pfet_01v8
spiceprefix=X
}
C {sky130_fd_pr/nfet_01v8.sym} -20 30 0 0 {name=M3
L=0.15
W=1
nf=1 
mult=1
ad="'int((nf+1)/2) * W/nf * 0.29'" 
pd="'2*int((nf+1)/2) * (W/nf + 0.29)'"
as="'int((nf+2)/2) * W/nf * 0.29'" 
ps="'2*int((nf+2)/2) * (W/nf + 0.29)'"
nrd="'0.29 / W'" nrs="'0.29 / W'"
sa=0 sb=0 sd=0
model=nfet_01v8
spiceprefix=X
}
C {devices/gnd.sym} 0 60 0 0 {name=l1 lab=GND}
C {devices/vdd.sym} 1280 460 0 0 {name=l2 lab=VDD}
C {devices/opin.sym} 620 260 0 0 {name=p1 lab=xxx}
C {devices/ipin.sym} -120 0 0 0 {name=p2 lab=A}
C {devices/opin.sym} 100 0 0 0 {name=p3 lab=Y}
C {devices/vdd.sym} 0 -60 0 0 {name=l3 lab=VDD}

@Matt Liberty I guess it was taken down because it's 2.5 years out of date but still comes up as the top result on google. The main branch of antmicro's fork is just an old version of the official one, but they had a nice side branch called "test-submodules-in-rtd" that contained the cell info, schematics & layout.

I've asked antmicro if they have scripts or other things that we could reuse

The sources are at https://github.com/antmicro/skywater-pdk

The PRs related to this have been merged and the docs are much nicer, eg https://skywater-pdk.readthedocs.io/en/main/contents/libraries/sky130_fd_sc_ls/cells/a2111o/README.html

Good to see PRs getting merged to prevent project apathy. Is the main catalog of cells up there ? https://skywater-pdk.readthedocs.io/en/main/contents/libraries/sky130_fd_sc_hd/README.html I think this would be the expected location for HD. Ah I see you have posted cell-index.html (good for seeing type matrix) but it doesn't have the nice one sentence cell function summary for quick reference, as most of my usage has been within a single type (HD) and then looking up the relative function by summary description.

Looks like antmicro's version included some changes that were not in PR#266. Compare https://skywater-pdk.readthedocs.io/en/main/contents/libraries/sky130_fd_sc_hd/README.html to https://htfab.github.io/skywater-pdk/contents/libraries/sky130_fd_sc_hd/README.html . Is there another relevant PR or should we manually copy cell_list.py to the official repo and include it in docs/conf.py?