cf-precheck

ChipFoundry MPW tapeout precheck tool. Validates user projects before shuttle submission by running a sequence of design-rule and consistency checks.

Installation

pip install cf-precheck

External tool dependencies

Some checks invoke external EDA tools that must be available on $PATH:

• KLayout — used by all Klayout DRC checks and the XOR check
• Magic — used by the optional Magic DRC check and LVS
• Netgen — used by the LVS check

Usage

cf-precheck -i <project_dir> -p <pdk_path> -c <caravel_root> [options] [check ...]

Required arguments

Optional arguments

Positional arguments

Pass one or more check names to run only those checks. If omitted, all applicable checks are run.

Example

# Run all checks
cf-precheck -i ./my_project -p $PDK_ROOT/sky130A -c ./caravel

# Run only specific checks
cf-precheck -i ./my_project -p $PDK_ROOT/sky130A -c ./caravel topcell_check gpio_defines

# Include the optional Magic DRC check
cf-precheck -i ./my_project -p $PDK_ROOT/sky130A -c ./caravel --magic-drc

# Skip certain checks
cf-precheck -i ./my_project -p $PDK_ROOT/sky130A -c ./caravel --skip-checks lvs oeb

Double-wide openframe

Double-wide projects are detected when exactly one of these GDS files is present:

gds/double_wide_openframe_project_wrapper.gds

Pass the double-wide harness root (not stock Caravel) as -c. That root must provide:

• gds/double_wide_openframe_project_wrapper_empty.gds
• verilog/rtl/__double_wide_openframe_project_wrapper.v (port-list golden)

cf-precheck \
  -i ../dw_openframe_user_project \
  -p $PDK_ROOT/sky130A \
  -c ../dw_openframe

XOR uses erase_box_double_wide.tcl (scaled openframe perimeter erase). OEB uses the openframe CVC path with GPIO indices 0..58.

Checks

Results

Check results are saved to <project>/.cf/project.json under the precheck key:

{
  "precheck": {
    "version": "1.0.0",
    "timestamp": "2026-03-17T12:00:00+00:00",
    "pdk": "sky130A",
    "passed": false,
    "checks": {
      "topcell_check": { "status": "pass", "duration_s": 1.2 },
      "gpio_defines": { "status": "fail", "duration_s": 0.8, "details": "..." }
    }
  }
}

Detailed logs are written to <project>/precheck_results/<timestamp>/logs/precheck.log.

License

Apache-2.0