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# BLE to Bluetooth Classic adapter

Older devices, like the TH-D74 radio only support Bluetooth Classic. iOS devices only support Bluetooth Low Energey (BLE). As such, you can't pair those devices together. This code provides a way to interface a device that exposes a serial profile over Bluetooth Classic, to an iOS device via BLE. Its main purpose is to use the TNC adapter built in the radio with a program that uses AX.25 packet like RadioMail or APRS.fi.

## Hardware

The code is based on the ESP32. Easiest is to use the excellent TinyPICO board [https://www.tinypico.com](https://www.tinypico.com)

**Do not get any other models like the TinyS3 as the ESP32-S3 does not support bluetooth classic.**

## Software

1. Install Aarduino IDE [https://www.arduino.cc](https://www.arduino.cc)
2. Install the ESP32 libraries. Follow this guide [https://docs.espressif.com/projects/arduino-esp32/en/latest/installing.html#installing-using-boards-manager](https://docs.espressif.com/projects/arduino-esp32/en/latest/installing.html#installing-using-boards-manager)
3. Install the TinyPICO library (not strictly needed but used to activate the LED). The TinyPICO Arduino helper library is available from the library manager inside the Arduino IDE.
4. Download this sketch
5. If your radio has a different name, change the code to reflect it
6. Flash sketch to TinyPICO
7. Download RadioMail on your phone [https://radiomail.app](https://radiomail.app)

## Pairing

1. On TH-D74 go to Bluetooth -> Pairing Mode
2. After a few seconds you should see a pin, press ok to accept.
3. Once paired you should see a green LED on the TinyPICO
4. Launch RadioMail. Go to Settings -> KISS TNC Modem -> Default TNC
5. "TNC Blues" should appear in discovery screen
6. Select TNC Blues, tap Done
7. Go to connection screen and select a packet station
8. When RadioMail connects to TNC Blues, blue LED should apprear on TinyPICO

## Limitations

- Code is just a proof of concept.
- The adapter has to pair to the radio, hence it needs the bluetooth name of the radio. Having the radio pair to the adapter should be feasible but never worked.
- Sometimes things get out of wack. Just restart the adapter.