A WebSocket and Serial bridge for ESP32 that connects smart servos (like Dynamixel) to web or serial clients. Control and monitor smart servos over a network connection or directly via USB/serial.

Note: This is an early version of the library. While it has been tested with several servo models, bugs may exist. Please report any issues you encounter.

• WebSocket server running on ESP32
• Serial port (USB/TTL) bridge for direct connection
• Direct binary communication with smart servos
• Support for text-based configuration commands (over WebSocket or Serial)
• Debug logging over Serial
• Tested with Dynamixel XL430-W250, FeeTech HLS3930M, WaveShare ST3215

• ESP32 development board (tested with Xiao ESP32-S3, QT Py ESP32-S3)
• Smart servo (tested with Dynamixel XL430-W250, FeeTech HLS3930M, WaveShare ST3215)
• Either:
  • Commercial: RobotStack Smart Servo Add-On Board - A ready-to-use interface board
  • DIY: Half-duplex UART circuit (see wiring diagram)

The ESP32 needs to be connected to the smart servo using a half-duplex UART configuration. You can either:

1. Purchase a RobotStack Smart Servo Add-On Board (recommended for reliable operation)
2. Build the Smart Servo Add-On Board, or similar according to the documentation

1. Clone this repository
2. Place into Arduino > Libraries folder
3. Install required libraries:
   • WebSocketsServer (external)
   • WiFi (included with ESP32 core)
4. Open Example
5. Configure your WiFi credentials in the code (for WebSocket mode)
6. Upload to your ESP32

Edit these parameters in the code:

const char* ssid = "yourSSID";
const char* password = "yourPassword";
#define TX_EN D3  // Change if using different pin

• WebSocket Mode:
  • Call bridge.begin(ssid, password); to start in WebSocket mode.
  • Connect to the ESP32's IP address on port 8080 using a WebSocket client.
  • Send binary to control the servo or text for custom messages.
  • To identify your IP, run the program with debugging enabled (eg. bridge.enableDebug(&IO);)
• Serial Mode:
  • Call bridge.begin(&Serial); to start in Serial mode.
  • Connect to the ESP32 via USB/TTL serial.
  • Send binary or text directly over the serial port.

• examples/WebSocketBridge/WebSocketBridge.ino – WebSocket mode
• examples/SerialBridge/SerialBridge.ino – Serial mode (raw relay)
• examples/SerialTextCommands/SerialTextCommands.ino – Serial mode (relay + text commands)
• websocket_test.html – WebSocket test client for debugging and testing connections

• Feetech Python SDK with WebSockets
• Dynamixel Python SDK with WebSockets

Enable debug logging output over Serial by uncommenting:

// bridge.enableDebug(&IO); // Enable debug output

Contributions are welcome! Please feel free to submit a Pull Request.

This project is licensed under the MIT License. See the LICENSE file for details.

Written by Nicholas Stedman ([email protected])