ESP32 BlueDuo Bridge

A dedicated wireless bridge for controlling the ELAD FDM-DUO transceiver via the "BlueDuo" Android App.

This firmware transforms an ESP32 (specifically the ESP32-2432S028R "Cheap Yellow Display") into a Bluetooth adapter. It enables a seamless wireless connection between the radio and an Android device, providing a GUI for connection status, and real-time data traffic monitoring.

Note: This project is an advanced alternative to the simpler solution based on the HC-05 Bluetooth module. This ESP32 version provides a visual interface, connection diagnostics, and larger data buffers for smoother operation.

Features

• Visual Feedback: The built-in TFT screen displays:
  • BlueDuo: Connection status with the Android App.
  • Client: MAC address of the connected tablet/phone.
  • Radio: Physical connection status (detected via data stream activity).
  • Time: Session duration timer.
  • Data Counters: Real-time TX (to radio) and RX (from radio) traffic.
• High Performance: Optimized buffers (16KB Serial / 8KB Bluetooth) to handle high-speed waterfall data without stuttering.

Hardware & Software Required

• Board: ESP32-2432S028R (often sold as "ESP32 Cheap Yellow Display").
• TRX: ELAD FDM-DUO.
• Cabling: A DB9 connector to connect to the radio's "EXT I/O" port.
• App: The BlueDuo Android application: http://my.eladit.com/download/sdr/BLUEDUO/

Wiring

Connect the ESP32 pins to the ELAD FDM-DUO EXT I/O port (DB9 connector):

ESP32 Pin	FDM-DUO (DB9) Pin	Signal Direction	Description
GPIO 22	Pin 6	Radio TX -> ESP32 RX	Receive data from Radio
GPIO 27	Pin 7	Radio RX <- ESP32 TX	Send commands to Radio
GND	Pin 5	GND	Common Ground

Power Supply (Important!)

• Power the ESP32 via its USB port.
• WARNING: Do NOT attempt to power the ESP32 from the FDM-DUO's EXT I/O port. The current capacity of the radio's accessory port is not documented for this load, and drawing too much current could damage the transceiver. This configuration has not been tested and is not recommended.

Installation / Compilation

1. Install the Arduino IDE

• Select ESP32 Dev Module as your board.

2. Install the ESP32 Board Manager (by Espressif Systems).
3. Install the TFT_eSPI library by Bodmer.
4. Crucial Step: Configure TFT_eSPI for the ESP32-2432S028R board.
   • Go to your Arduino libraries folder -> TFT_eSPI.
   • Edit User_Setup.h by replacing its content with the correct configuration for the CYD board.
5. Open esp32-blueduo-bridge.ino.
6. Select Board: ESP32 Dev Module (or similar generic ESP32).
7. Upload!

Usage

1. Turn on your ELAD FDM-DUO.
2. Power on the ESP32 via USB. The screen will show "Waiting...".
3. On your Android device, go to Bluetooth settings.
4. Pair with the device named BLUEDUO.
5. Open the BlueDuo app.
6. Tap Connect.
7. The screen on ESP32 should turn "Connected" and the RX data counter should start.

License

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

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Author: Leszek HF7A