Web Serial Terminal for microcontrollers

A modern web-based serial terminal for ESP32, Arduino, and other microcontrollers using the Web Serial API. This terminal provides a clean, terminal-style interface with customizable baud rates and line endings, compatible with any USB serial device.

Features

• Web Serial API Integration: Connect directly to ESP32, Arduino, and other microcontroller devices through your browser
• Multiple Baud Rate Support: 9600, 57600, 74880, 115200, 230400, 460800, 921600, and custom rates
• Line Ending Options: None, LF (\n), CRLF (\r\n), CR (\r)
• Terminal-style Interface: Green-on-black color scheme with monospace font
• Command Input: Dedicated input area for sending commands
• Auto-scroll: Automatically scrolls to show latest output
• Clear Command: Type "clear" to clear the terminal
• Real-time Communication: Bidirectional communication with connected devices

Browser Compatibility

This application requires a browser that supports the Web Serial API:

• Google Chrome (version 89+)
• Microsoft Edge (version 89+)
• Brave Browser
• Other Chromium-based browsers

Note: Firefox and Safari do not currently support the Web Serial API.

Usage

1. Open the Terminal

   • Open index.html in a supported browser
   • No web server required - works as a local file

2. Connect to Device

   • Click "Connect" button
   • Select your microcontroller device from the browser's device picker
   • Choose appropriate baud rate (default: 115200)
   • Select line ending format if needed

3. Send Commands

   • Type commands in the input field at the bottom
   • Press Enter to send
   • Commands will appear in the terminal with a ">" prefix

4. Monitor Output

   • All device output appears in the main terminal area
   • Terminal auto-scrolls to show latest messages
   • Use "clear" command to clear the terminal

5. Disconnect

   • Click "Disconnect" when finished
   • Connection status is shown in the top-right corner

Configuration Options

Baud Rates

• 9600 (common for basic Arduino projects)
• 57600
• 74880 (ESP8266/ESP32 boot messages)
• 115200 (default, most common)
• 230400
• 460800
• 921600
• Custom (enter any valid baud rate)

Line Endings

• None: No line ending characters
• LF (\n): Unix-style line ending
• CRLF (\r\n): Windows-style line ending
• CR (\r): Classic Mac-style line ending

Supported Devices

This terminal works with any device that communicates over USB serial, including:

ESP Family:

• ESP32 (all variants)
• ESP8266 (NodeMCU, Wemos D1, etc.)

Arduino Boards:

• Arduino Uno, Nano, Mini
• Arduino Mega, Leonardo, Micro
• Arduino Pro, Pro Mini

Other Compatible Devices:

• STM32 development boards
• Raspberry Pi Pico
• Teensy boards
• Any microcontroller with USB-to-serial conversion

File Structure

ESP32-Web-Serial-Terminal/
├── index.html          # Main application file
└── README.txt          # This documentation file

Technical Details

• Language: HTML5, CSS3, JavaScript (ES6+)
• API: Web Serial API
• Dependencies: None (vanilla JavaScript)
• File Size: ~8KB (single file)
• Framework: None (pure web technologies)

Common Commands

Here are some useful commands you can try once connected:

ESP32/ESP8266 Commands:

AT                      # Test AT command response (if AT firmware)
AT+GMR                  # Get firmware version (if AT firmware)
help                    # Show available commands (device-dependent)
ls                      # List files (if filesystem enabled)
reboot                  # Restart the device

Arduino Commands:

help                    # Show available commands (sketch-dependent)
status                  # Get device status (if implemented)
reset                   # Reset device (if implemented)

Universal Commands:

clear                   # Clear the terminal (web terminal command)

Note: Available commands depend on the firmware/sketch running on your device.

Troubleshooting

Connection Issues

• Ensure your device is properly connected via USB
• Check that no other serial monitor is using the same port
• Try different baud rates if communication appears garbled
• Make sure your browser supports Web Serial API

Display Issues

• If text appears wrapped, the terminal uses horizontal scrolling
• Use browser zoom controls if text is too small/large
• Terminal maintains monospace formatting for proper alignment

Permission Issues

• Some browsers may require HTTPS for Web Serial API
• Try using a local web server if file:// protocol causes issues

Development

This is a single-file application built with vanilla web technologies. To modify:

1. Edit the HTML, CSS, or JavaScript directly in index.html
2. No build process or dependencies required
3. Test by opening the file in a supported browser

License

This project is open source and available for modification and distribution.

Contributing

Feel free to submit issues, feature requests, or pull requests to improve this terminal.

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Note: This terminal is designed for development and debugging purposes. Always ensure your ESP32/Arduino code handles serial communication appropriately to avoid infinite loops or excessive output that might overwhelm the browser.