Modeling problems on sky130_fd_sc_hd liberty files

20Mhz commented 4 years ago

Documenting 4 issues noted on sky130_fd_sc_hd.

Wrong pin used as related_groun_pin. Synopsys Library Compiler, complain: Error: Line 57389, Cell 'sky130_fd_sc_hd__dlclkp_1', pin 'M0', An invalid attribute 'related_ground_pin' is found. (LBDB-27)

        pin ("M0") {
            direction : "internal";
            internal_node : "M0";
            related_ground_pin : "VGND";  /* VNB is wrong*/
            related_power_pin : "VPWR";
        }

Missing pg_pin on level shifter cell Synopsys Library Compiler, complain: Error: Line 82105, Cell 'sky130_fd_sc_hd__lpflow_lsbuf_lh_hl_isowell_tap_1', pg_pin 'VPWR', An invalid attribute 'VNB' is found. (LBDB-27)

pg_pin ("VPWR") {
            pg_type : "primary_power";
            related_bias_pin : "VNB"; /* VNB pin is missing*/
            voltage_name : "VPWR";
}

Missing Standard cell main rail attribute sky130_fd_sc_hd__lpflow_lsbuf_lh_hl_isowell_tap_1 is missing std_cell_main_rail : true on pg_pin group for 'VPWR'. This is needed so implementation tools can insert legally without understanding physical view.
CSS section showing up without table definition. Likely it shouldn't be on sky130_fd_sc_hd__ff_n40C_1v95.lib (may be on other opconds too) ccsn_dc table is missing:

 ccsn_first_stage () {
                    dc_current ("ccsn_dc") {

mithro commented 4 years ago

FYI - The code which generates the liberty files can be found at https://github.com/google/skywater-pdk/blob/master/scripts/python-skywater-pdk/skywater_pdk/liberty.py

mithro commented 4 years ago

Will need to do more investigation if this needs changes in the output generation or in the source json data.

20Mhz commented 4 years ago

For 1, I think you need the change the cell json. As seen here: sky130_fd_sc_hd__dlclkp_2__ff_100C_1v65.lib.json 840: "related_ground_pin": "VNB",
For 2, this is similar but VNB pg_pin is not listed here: sky130_fd_sc_hdlpflow_lsbuf_lh_hl_isowell_tap_1ff_100C_1v65.lib.json
I think 3 is similar to 2, and should be added to the pg pin attributes.
Finally 4 may be related to liberty.py, but will have to look further.

20Mhz commented 3 years ago

As noted in #288 , the fix for 2 ( LS power pin) should actually be using the NWELL pin which is VPB, not VNB. This naming convention is awfully confusing.

glzhou97 commented 1 year ago

I encountered the same problem with issue 1 mentioned here and in #391. May I ask what is the solution for this issue?

sifferman commented 11 months ago

I am also encountering this issue. Has anyone had success with using Synopsys tools with this PDK?

Example

I am trying to use sky130 with Design Compiler, but lc_shell can't load the "sky130_fd_sc_hd__tt_025C_1v80.lib" file.

lc_shell version T-2022.03-SP5

lc_shell

read_lib $SKYWATER_PDK/libraries/sky130_fd_sc_hd/latest/timing/sky130_fd_sc_hd__tt_025C_1v80.lib
write_lib sky130_fd_sc_hd__tt_025C_1v80 -format db -output library.db

Error: Line 57389, Cell 'sky130_fd_sc_hd__dlclkp_1', pin 'M0', An invalid attribute 'related_ground_pin' is found. (LBDB-27)
Error: Line 57628, Cell 'sky130_fd_sc_hd__dlclkp_2', pin 'M0', An invalid attribute 'related_ground_pin' is found. (LBDB-27)
Error: Line 57867, Cell 'sky130_fd_sc_hd__dlclkp_4', pin 'M0', An invalid attribute 'related_ground_pin' is found. (LBDB-27)
Error: Line 82105, Cell 'sky130_fd_sc_hd__lpflow_lsbuf_lh_hl_isowell_tap_1', pg_pin 'VPWR', An invalid attribute 'VNB' is found. (LBDB-27)
Error: Line 82239, Cell 'sky130_fd_sc_hd__lpflow_lsbuf_lh_hl_isowell_tap_2', pg_pin 'VPWR', An invalid attribute 'VNB' is found. (LBDB-27)
Error: Line 82373, Cell 'sky130_fd_sc_hd__lpflow_lsbuf_lh_hl_isowell_tap_4', pg_pin 'VPWR', An invalid attribute 'VNB' is found. (LBDB-27)
Error: Line 82650, Cell 'sky130_fd_sc_hd__lpflow_lsbuf_lh_isowell_tap_1', pg_pin 'VPWR', An invalid attribute 'VNB' is found. (LBDB-27)
Error: Line 82784, Cell 'sky130_fd_sc_hd__lpflow_lsbuf_lh_isowell_tap_2', pg_pin 'VPWR', An invalid attribute 'VNB' is found. (LBDB-27)
Error: Line 82918, Cell 'sky130_fd_sc_hd__lpflow_lsbuf_lh_isowell_tap_4', pg_pin 'VPWR', An invalid attribute 'VNB' is found. (LBDB-27)
Error: Line 164125, Cell 'sky130_fd_sc_hd__sdlclkp_1', pin 'M0', An invalid attribute 'related_ground_pin' is found. (LBDB-27)
Error: Line 164449, Cell 'sky130_fd_sc_hd__sdlclkp_2', pin 'M0', An invalid attribute 'related_ground_pin' is found. (LBDB-27)
Error: Line 164773, Cell 'sky130_fd_sc_hd__sdlclkp_4', pin 'M0', An invalid attribute 'related_ground_pin' is found. (LBDB-27)

20Mhz commented 11 months ago

Yes, check the scripts below, we patched the .libs before compiling: https://github.com/20Mhz/skywater-pdk/tree/synopsys_pull/vendor/synopsys

Reach out on #vendor-synopsys or to me directly on slack if you still have issues

RTimothyEdwards commented 11 months ago

You should be using the repository at https://github.com/efabless/skywater-pdk-libs-sky130_fd_sc_hd, which has been patched. However, while the incorrect pg_pin attributes have been fixed, it appears that the related_ground_pin errors are still in the .lib files; 84 instances throughout the .lib files (although fortunately they are restricted to the HD library). Since those are easy to detect and fix, I will do that now.

RTimothyEdwards commented 11 months ago

This issue has now been corrected in the Efabless fork.

google / skywater-pdk

Modeling problems on sky130_fd_sc_hd liberty files #183

Example