ESP32-Based Real-Time Morse Code Communication System with Digital Logic Simulation
DotDash is a real-time Morse code communication system implemented entirely on an ESP32, combining touch input, OLED display, live web portal, and digital logic gate simulation for educational purposes.
Users input Morse code through a touch-sensitive pin, and the system provides instant feedback:
- Line 1 (OLED): Scrolling dots and dashes representing raw Morse input
- Line 2 (OLED): Decoded letters as they are interpreted
- Progress bar (OLED): Visual indicator of touch duration, showing dot vs dash
The local web interface mirrors the OLED display, updating live:
- Raw Morse in one section
- Decoded letters in another
DotDash automatically detects:
- Letter gaps (1s): Converts current Morse token to a letter
- End of input (4s): Finalizes the message display on OLED and in the web portal
Additionally, live Serial Monitor output mirrors the OLED and web portal, enabling debugging or monitoring via USB.
- Touch-Based Morse Input: Single pin differentiates dots (
.) and dashes (-) based on press duration. - OLED Feedback: Live scrolling display of Morse symbols and decoded letters.
- Progress Visualization: Horizontal bar indicates touch duration; fills progressively as touch is held.
- Digital Logic Simulation: Implements combinational logic (AND, OR, NOT gates) to encode letters A-Z to Morse code using 5-bit binary representation.
- Web Interface: Access via ESP32 Wi-Fi AP with terminal-styled interface; live updates of Morse and decoded letters.
- Automatic Decoding: Detects letter gaps and message completion automatically.
- Configurable Timings: Adjust
DOT_TIME,CHAR_GAP,END_GAP, and other parameters to suit user preference. - Serial Monitor Integration: Real-time output of Morse and decoded letters for development and monitoring.
DotDash includes a 5-bit to Morse encoder that simulates combinational logic circuits:
- 5 Input Bits (b4, b3, b2, b1, b0) represent letters A-Z (values 0-25)
- 5 NOT Gates invert each input bit
- 26 AND Gates detect unique 5-bit patterns for each letter
- 1 Output Multiplexer selects the corresponding Morse code
Each letter is encoded using Boolean algebra in Sum-of-Products (SOP) form:
| Letter | Binary | Boolean Expression | Morse |
|---|---|---|---|
| A | 00000 | ¬b4 · ¬b3 · ¬b2 · ¬b1 · ¬b0 | .- |
| B | 00001 | ¬b4 · ¬b3 · ¬b2 · ¬b1 · b0 | -... |
| C | 00010 | ¬b4 · ¬b3 · ¬b2 · b1 · ¬b0 | -.-. |
| ... | ... | ... | ... |
| Z | 11001 | b4 · b3 · ¬b2 · ¬b1 · b0 | --.. |
Note: · represents AND, ¬ represents NOT, + represents OR
- NOT Gates: 5 (one per input bit)
- 5-input AND Gates: 26 (one per letter)
- Total: 32 gates for complete A-Z decoder
This implementation demonstrates how combinational logic circuits can be used in embedded systems for character encoding, making DotDash both a functional communication tool and an educational platform for digital design concepts.
- ESP32 Responsibilities: Wi-Fi Access Point, DNS redirect, web server, OLED control, touch input reading, scrolling logic, progress bar animation, digital logic gate simulation, and live Serial output.
- Touch Input: Uses
touchRead()with dynamic threshold calibration to detect touch events and differentiate dots vs dashes. - OLED Display (128x64 SSD1306): Scrolling Morse line, decoded letter line, and touch progress bar with real-time fill animation.
- Web Portal: Terminal-styled interface with two separate divs for live Morse symbols and decoded letters; updates every 200ms.
- Logic Gate Simulation: AND, OR, NOT, and XOR functions simulate hardware-level combinational logic for character encoding.
- Timing Parameters:
| Parameter | Default | Description |
|---|---|---|
DOT_TIME |
200 ms | Max duration for a dot |
DASH_TIME |
600 ms | Max duration for a dash |
CHAR_GAP |
1000 ms | Gap to detect end of letter |
END_GAP |
4000 ms | Gap to detect end of message |
DEBOUNCE |
30 ms | Touch debounce delay |
- Morse Table: Supports A–Z; easily extendable to 0–9 and punctuation.
- ESP32 Development Board (any variant with touch pins)
- 128x64 OLED Display (SSD1306, I2C interface)
- Touch-sensitive surface or conductive material connected to GPIO 4
- Jumper wires for connections
| Component | Pin |
|---|---|
| Touch Input | GPIO 4 |
| OLED SDA | GPIO 21 |
| OLED SCL | GPIO 22 |
- Arduino IDE or PlatformIO
- ESP32 Board Support (via Board Manager)
- Libraries:
WiFi.h(built-in)DNSServer.h(built-in)WebServer.h(built-in)Wire.h(built-in)U8g2lib.h(install via Library Manager)
- Install Arduino IDE and add ESP32 board support
- Install U8g2 library via Library Manager
- Connect hardware according to pin configuration
- Upload the code to your ESP32
- Connect to WiFi AP:
- SSID:
DotDash - Password: (none - open network)
- SSID:
- Access web interface at
http://192.168.4.1
DSD Morse Encoder Started (A-Z Complete)
Access at: 192.168.4.1
Pressed!
Released! Duration: 150 ms | Symbol: .
Current token: .
Decoded char: E
Live Morse: . | Letters: E
Pressed!
Released! Duration: 650 ms | Symbol: -
Current token: -
Decoded char: T
Live Morse: - | Letters: ET
Message complete: HELLO
- Terminal aesthetic with green on black background
- Real-time updates every 200ms
- Responsive design for mobile and desktop
- Visual sections:
- Raw Morse code display
- Decoded letters display
- High contrast for enhanced visibility
Portal automatically opens when connecting to DotDash network via captive portal redirect.
- Power on the ESP32 with the DotDash firmware.
- Connect to the Wi-Fi network
DotDash(open, no password). - Open browser and navigate to
http://192.168.4.1/(or wait for captive portal). - Touch the pad to input Morse code:
- Short press (<200ms) = dot (
.) - Long press (>200ms) = dash (
-)
- Short press (<200ms) = dot (
- Watch feedback on OLED display and web portal simultaneously.
- Wait 1 second between letters for automatic decoding.
- Wait 4 seconds after last input for message finalization.
- Calibrate touch sensitivity by adjusting
THRESHOLD_FACTOR(default 0.7) - Use consistent pressure for reliable dot/dash detection
- Practice timing: quick taps for dots, held presses for dashes
- Monitor the progress bar for visual feedback on press duration
DotDash serves as an excellent learning tool for:
- Embedded Systems: ESP32 programming, peripheral interfacing
- Digital Logic Design: Boolean algebra, combinational circuits, gate-level implementation
- Web Technologies: Server-client communication, real-time updates
- Communication Systems: Morse code protocol, encoding/decoding
- Human-Computer Interaction: Touch sensing, visual feedback, progress indicators
The digital logic simulation demonstrates how software can model hardware circuits, bridging the gap between theoretical computer science and practical embedded applications.
- Add support for numbers (0-9) and punctuation
- Implement message history and playback
- Add audio feedback (buzzer/speaker)
- Multi-user communication mode
- FPGA implementation of logic gates
- Mobile app integration via Bluetooth
- Machine learning for adaptive timing calibration
This project is open-source. Feel free to modify and distribute with attribution.
|
Upayan Mazumder
|
Atharva Sharma
|
Siddharth Verma
|
Divyansh Saxena
|
Aditya Rawat
|
This project was developed as part of the coursework at VIT Vellore under the guidance of Dr. Naveen Mishra.