🏗 OpenLane-Lite Usage Guide — SemiDevKit

This document explains how to run OpenLane-Lite, the minimal RTL-to-GDSII backend flow included in SemiDevKit.

The goal of OpenLane-Lite is to provide a lightweight, reproducible, and educational physical design flow that demonstrates the core concepts of modern digital implementation without requiring a full commercial or production PDK setup.

📦 1. Requirements

OpenLane-Lite requires the following environment:

• 🐳 Docker (Linux or WSL2 recommended)
• 🛠 make (optional, but useful)
• 🐍 Python 3.x (for helper and analysis scripts)
• 🪟 WSL2 Ubuntu (required if running on Windows)

✔ Verify Docker installation

docker --version
docker run hello-world

If you see the message “Hello from Docker!”, Docker is functioning correctly.

📁 2. Directory Structure (Simplified)

The OpenLane-Lite module is organized as follows:

openlane/openlane-lite/
 ├ docker/
 │   ├ run_in_docker.sh        # Docker execution wrapper
 │   └ Dockerfile              # Minimal OpenLane environment
 ├ scripts/
 │   ├ run_flow.sh             # Main flow script
 │   ├ prepare_design.sh       # Design preparation helper
 │   └ extract_results.py      # Result extraction utility
 ├ designs/
 │   └ example_top/
 │       ├ config.tcl          # Design configuration
 │       ├ src/                # RTL source files
 │       └ runs/               # Generated run results
 ├ pdks/                       # Minimal educational PDK subset
 └ README.md

▶️ 3. Running the Flow

Move into the OpenLane-Lite directory:

cd openlane/openlane-lite

3.1 Basic Execution

Run the default example flow:

./docker/run_in_docker.sh ./scripts/run_flow.sh

This command executes the following steps:

1. RTL synthesis (Yosys)
2. Floorplanning
3. Placement
4. Clock Tree Synthesis (CTS)
5. Routing
6. GDSII export

📂 Results are generated under:

designs/<design-name>/runs/<timestamp>/

🧩 4. Running a Specific Design

To run a specific design directory, pass the design path explicitly.

Example: bundled sample design

./docker/run_in_docker.sh ./scripts/run_flow.sh designs/example_top

Example: custom design

./docker/run_in_docker.sh ./scripts/run_flow.sh ./designs/my_design

Each design directory must include:

• config.tcl
• src/ (RTL files)

⚙️ 5. Editing the Configuration

Each design directory contains a config.tcl file that controls key physical design parameters, such as:

• Core utilization
• Power grid settings
• Clock period
• Routing layers
• Pin placement constraints

Example snippet

set ::env(DESIGN_NAME) "example_top"
set ::env(CLOCK_PERIOD) "10"
set ::env(FP_CORE_UTIL) "45"

After modifying the configuration, simply rerun the flow to apply changes.

📊 6. Extracting Results

A helper script is provided to summarize key metrics from a completed run.

python scripts/extract_results.py designs/example_top/runs/<timestamp>

This script extracts:

• ⏱ Timing summary
• 🔌 Power estimation
• 📐 Area utilization
• 🚫 DRC violation count
• 📄 GDS output location

🛠 7. Troubleshooting

❌ Docker cannot find device

→ Ensure Docker Desktop (Windows/macOS) or Docker Engine (Linux) is running.

❌ Permission denied when running scripts

chmod +x docker/run_in_docker.sh
chmod +x scripts/run_flow.sh

❌ No PDK found

Ensure the directory structure includes:

openlane-lite/pdks/

OpenLane-Lite ships with a minimal PDK subset intended for educational use only.

📝 8. Notes and Limitations

• Full OpenLane flows require complete PDKs (e.g. Sky130, GF180)
• OpenLane-Lite intentionally uses a reduced configuration
• The generated GDS files are compatible with standard viewers such as KLayout
• This flow is intended for learning, experimentation, and prototyping, not tape-out

🎯 You have now completed the OpenLane-Lite flow