AXON Servo Cross-Platform Programmer

The Axon servo is an amazing servo used by many FTC teams. One of the downsides of the servo is that to program it, you need a Windows laptop. For those who do not have access to one or prefer using macOS or Linux, this can be a significant limitation. This project was created to solve that exact problem. By reverse-engineering the communication between the official Windows-based Axon programmer and the USB HID device, we developed a lightweight, cross-platform Python tool with a modern GUI. This program is in its VERY early stages. If you have experience reverse engineering protocols for USB devices, contributions are welcome! This project is a Python-based tool that communicates with a custom USB HID servo adapter (based on the SA33/USBBootloader) to program and test Axon servos. It replicates the behavior of a proprietary .exe tool by sending low-level HID reports to the device and interpreting its responses.

🔧 Features

• ✅ Detects when a servo is plugged into the USB adapter
• 🔄 Continuously polls the adapter for status
• ⚙️ Uses hidapi (via the hid Python package)
• 🖥️ Works on Windows, Linux, and macOS
• ✨ Modern GUI built with PyQt6 and PyQt6-Fluent-Widgets.

🖼️ GUI

A modern GUI has been developed using PyQt6 and PyQt6-Fluent-Widgets, with features such as:

• Real-time status display (servo connected, current position, etc.)
• Interactive controls for configuration and testing
• Visual feedback and logging
• Cross-platform builds for Windows, macOS, and Linux

🚧 Future Plans

The current version of this project only scratches the surface of what the official Axon Programming Software can do. The long-term goal is to fully recreate and extend all of its functionality — in a free, open-source, and cross-platform package.

Planned features include:

• 🔌 Automatic adapter and servo detection on all supported OSes
• 🔄 Read/write servo configuration parameters (PID values, direction, etc.)
• ⬆️ Upload new firmware directly to the servo (Continous or Positional)
• 💾 Save and load profiles for repeatable tuning
• 🧪 Test mode to control servo position or speed from the GUI
• 🔍 Log and decode all USB traffic for debugging and advanced development

To support these features, we will continue reverse-engineering the USB HID protocol used by the original Windows .exe and documenting the command structure. This tool is being built by FTC teams, for FTC teams, with the goal of making Axon servo configuration accessible to everyone, not just those with Windows laptops. If you'd like to contribute to the protocol decoding, GUI development, or feature implementation, feel free to open an issue or pull request.

📦 Requirements

• Python 3.6+
• hidapi
• ttkthemes
• PyQt6
• PyQt6-Fluent-Widgets

Install dependencies:

pip install hidapi ttkthemes PyQt6 PyQt6-Fluent-Widgets

On Linux/macOS, you may also need:

sudo apt install libhidapi-libusb0  # Debian/Ubuntu
brew install hidapi                 # macOS

🛠️ Setup (Linux/macOS Users)

To avoid running as root, add a udev rule:

1. Create file /etc/udev/rules.d/99-servo.rules:

SUBSYSTEM=="usb", ATTRS{idVendor}=="0471", ATTRS{idProduct}=="13aa", MODE="0666"

2. Reload rules:

sudo udevadm control --reload
sudo udevadm trigger

🚀 Usage

Install the package using pip:

pip install axon-programmer

Then run the GUI:

axon-programmer

You will see a GUI window to interact with the servo.

🧪 How It Works

• The adapter uses a known HID interface (VID=0x0471, PID=0x13aa)

• A specific OUT report must be sent to trigger a status response:

  04 8A 00 00 04 00 00 00 ... (total 64 bytes)
  

• The adapter replies with a 64-byte IN report:

  • If servo is plugged in: 04 01 00 01 01 03 ...
  • If servo is not plugged: 04 01 FA 00 01 00 ...