Apple System Management Control (SMC) Tool

A lightweight Command-Line Interface (CLI) for macOS to interact with the Apple System Management Controller.
This tool allows users to monitor sensor data, inspect fan configurations, and read/write SMC keys.

Features

• Key Discovery: List all available SMC keys with optional pattern matching.
• Fan Diagnostics: View decoded fan speeds and status information.
• Low-level Access: Read and write (hex) directly to specific SMC keys.
• Minimalist: Fast execution with no heavy dependencies.

Technical Implementation

Built with C++20, this tool features an advanced interpretation engine for SMC data:

• Automatic Type Detection: Automatically fetches and parses SMC attributes to determine the correct data type (e.g., sp78, fpe2, ui32).
• Endianness Handling: Intelligent MSB/LSB (Most/Least Significant Bit) conversion based on the key's internal attributes.

Installation

Build and install the tool to /usr/local/bin, use the terminal:

git clone https://github.com/great-andy/AppleSMC.git
cd AppleSMC
make install

Uninstallation

To remove the tool from /usr/local/bin, use the terminal:

cd AppleSMC
make uninstall

Usage

smc [options]

Available Options

Option	Description
-l, --list=['*|?']	List all keys and values. Supports optional pattern matching.
-f, --fans	List decoded fan information (RPM, status, etc.).
-k, --key <key>	Set the specific key to read from or write to.
-r, --read=[key]	Read the value of a key. Optional: provide key directly.
-w, --write <value>	Write a hex value to the specified key.
-h, --help	Print help message and exit.
-v, --version	Print version information.

Examples

List all temperature sensors:

smc --list='T*'

Check fan status:

smc -f

Read a specific key:

# Example: Read incoming power from AC adapter (in milliwatts)
smc -rACPW

Write a hex value to a key:

# Example: Manually switch the MagSafe led off
sudo smc -k ACLC -w 1

# Example: Reset the MagSafe led to system state
sudo smc -k ACLC -w 0

Important: Root Access

SMC writing operations require sudo.

Deep Metadata Inspection

The tool doesn't just read values; it queries the internal SMC key information to ensure data integrity:
KEY [TYPE|ATTRIBUTES] VALUE (RAW_HEX)

Example:

$ smc -rACPW
ACPW  [ui32|95]  19980  (0c 4e 00 00)

• Type: Displays the internal data type (e.g., ui32, fpe2).
• Attributes: Reveals the internal SMC attribute flags, providing insight into key permissions and behavior.
• Value: Converts the raw SMC bytes into a human-readable format based on the detected data type and attributes.
• Raw Hex: Always prints the raw hex dump alongside the parsed value for manual verification.

⚠️ Warning

Writing values to the SMC via --write can be dangerous. The SMC manages critical hardware functions like thermal regulation and power management. Incorrect values may lead to hardware instability or damage. Use this tool at your own risk.

License

Licensed under the GNU General Public License v3.0.

Disclaimer

This tool interacts with the system hardware via IOKit. Use at your own risk. The authors are not responsible for any hardware issues.