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

Flag	Description
`-i`, `--input-directory`	Path to the user project directory
`-p`, `--pdk-path`	Path to the PDK installation (variant-specific, e.g. `$PDK_ROOT/sky130A`)
`-c`, `--caravel-root`	Path to the golden Caravel root (or set `$GOLDEN_CARAVEL`)

Optional arguments

Flag	Description
`-o`, `--output-directory`	Output directory (default: `<project>/precheck_results/<timestamp>`)
`--magic-drc`	Include the Magic DRC check (off by default)
`--skip-checks check [...]`	Skip specific checks
`-v`, `--verbose`	Show verbose/debug output
`--version`	Print version and exit

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

Field	Value
Type	`double_wide`
User module	`double_wide_openframe_project_wrapper`
Top module	`double_wide_chip_io`
Golden wrapper	`double_wide_openframe_project_wrapper_empty`
User area	6754.63 × 4766.63 µm (59 GPIOs)

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

Check	Description
`topcell_check`	Validates the top cell name in the GDS
`gpio_defines`	Validates GPIO directives in `verilog/rtl/user_defines.v`
`pdn`	Power distribution network check
`metal_check`	Metal density check
`xor`	XOR comparison against the golden wrapper to detect out-of-bounds edits
`magic_drc`	Full DRC using Magic (optional, off by default)
`klayout_feol`	Klayout Front End Of Line DRC
`klayout_beol`	Klayout Back End Of Line DRC
`klayout_offgrid`	Klayout off-grid violations check
`klayout_metal_minimum_clear_area_density`	Klayout metal density check
`klayout_pin_label_purposes_overlapping_drawing`	Klayout pin/label overlap check
`klayout_zero_area`	Klayout zero-area cell check
`spike_check`	Detects invalid paths in the design
`illegal_cellname_check`	Detects cells with illegal names
`oeb`	Output-enable-bar signal connectivity check
`lvs`	Layout vs. Schematic check

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

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1.3.6

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1.0.1

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1.0.0

Mar 17, 2026

cf-precheck 1.3.5

cf-precheck

Installation

External tool dependencies

Usage

Required arguments

Optional arguments

Positional arguments

Example

Double-wide openframe

Checks

Results

License

Key dates

1 maintainer

License expression

Requires

Download files

Source Distribution

Built Distribution

File details

File metadata

File hashes

Provenance

File details

File metadata

File hashes

Provenance

Release history Release notifications | RSS feed