lid-angle-rs

A Rust command-line tool to read and display your MacBook's hidden lid angle sensor in real-time.

Overview

This tool uses the IOKit HID framework to access the MacBook's built-in lid angle sensor and displays the current angle of your laptop's lid in real-time in the terminal.

Features

• 🔍 Automatic detection of the lid angle sensor
• 📊 Real-time angle display with visual progress bar
• 🎯 High precision (0.01 degree resolution)
• 🚀 Written in Rust for performance and safety

Requirements

• macOS 11.0+ (Big Sur or later)
• Compatible MacBook:
  • MacBook Pro 16-inch (2019) or newer
  • MacBook Pro (M1/M2/M3/M4)
  • MacBook Air (M1/M2/M3/M4)
  • Note: Not all models have this sensor; compatibility varies

Installation

From crates.io

cargo install lid-angle

From source

git clone https://github.com/wangfu91/lid-angle-rs.git
cd lid-angle-rs
cargo build --release

The compiled binary will be available at target/release/lid-angle (or run with cargo run --release during development).

Usage

Simply run the tool:

Install once, then run:

lid-angle

The tool will:

1. Search for the lid angle sensor
2. Display real-time angle updates as you open/close your MacBook lid
3. Show a visual progress bar representing the angle (0-180°)

Press Ctrl+C to exit.

Example Output

MacBook Lid Angle Sensor Reader
================================

Searching for lid angle sensor...
✓ Lid angle sensor found and opened

Reading lid angle in real-time (press Ctrl+C to exit)...

Lid Angle: 125.43° [█████████████████████████████████████            ]

How It Works

This tool interfaces with macOS's IOKit HID framework to access the lid angle sensor. The sensor is exposed as a HID device with the following properties:

• VendorID: 0x05AC (Apple)
• ProductID: 0x8104
• Usage Page: 0x0020 (Sensor)
• Usage: 0x008A (Orientation)

The implementation is based on reverse-engineering work from the LidAngleSensor Objective-C project.

Troubleshooting

"No lid angle sensor found"

If you see this error:

1. Check device compatibility: Run the diagnostic command:

   hidutil list --matching '{"VendorID":0x05AC,"ProductID":0x8104,"PrimaryUsagePage":32,"PrimaryUsage":138}'

   If this returns no devices, your MacBook may not have the sensor.

2. Try with elevated privileges:

   sudo lid-angle

3. Verify your MacBook model: The sensor is typically available on MacBook Pro models from 2019 onwards.

Permission issues

If you encounter permission errors, run the tool with sudo:

sudo lid-angle

Credits

This project was inspired by and based on the research from:

• LidAngleSensor by Sam Henri Gold (Objective-C implementation)
• mac-angle (C++ implementation)

Technical Details

The tool uses the following Rust crates:

• core-foundation and core-foundation-sys: For CoreFoundation types and bindings
• Direct FFI bindings to IOKit HID framework

The lid angle sensor reports values as 16-bit integers in units of 0.01 degrees, providing a range from 0° (closed) to ~180° (fully open).

License

MIT License - see LICENSE file for details.

Contributing

Contributions are welcome! Please feel free to submit issues or pull requests.