Ham PTT

Bluetooth PTT switch for ham radio transmitters like Baofeng UV-5R.
Board helps to control transmitter from PC.

Motivation

Testing of UART interface showed unstable connection. During transmit via UART an usb-ttl chip periodically crashes and stops working. Cause is some radio strong interference on USB cable. So Bluetooth serial protocol stack (SSP) chosen instead.

Schematic

Host -> (Bluetooth) -> Esp-32 Arduino -> Relay -> Transmitter PTT button

• Hardware

  • Host PC with Bluetooth (tested Ubuntu 20.04)
  • Esp32 DevKit v1 (or similar esp32)
  • Relay shield
  • Baofeng UV-5R

Examples

• Find BT devices hcitool scan
• Python

from hamptt import open_ptt

with open_ptt(bt_addr="A0:B1:C2:D3:E4:F5") as ptt:
    ptt.begin()
    # I.e. play message to transmitter or something else
    ptt.end()

Install

• Host PC machine

  • Python 3.8

  • Bluetooth's libs (required for pybluez)

    sudo apt-get install bluez libbluetooth-dev
    

  • Pip

    python3 -m pip install "hamptt[bt]"
    

• Esp32

  • Upload sketch to your esp-32 via PlatformIO
    NOTE! Check your board config in platformio.ini (see: https://platformio.org/)

    pio run -t upload
    

  • Connect pins Esp-32 to relay

    • VVC -> Relay +
    • GND -> Relay -
    • GPIO D25 -> Relay IN

  • Connect relay and audio, for Baofeng UV-5R it looks like:

    
    NOTE: You can rebuild your hands-free cable or buy another one

Development

• Build and install

  pip3 uninstall hamptt
  rm -rf dist && poetry build && pip3 install ./dist/*.whl
  

• Publish

  • Prepare

    poetry config repositories.testpypi https://test.pypi.org/legacy/
    poetry config pypi-token.testpypi <TOKEN>
    
    poetry config repositories.pypi https://upload.pypi.org/legacy/
    poetry config pypi-token.pypi <TOKEN>
    

  • Publish

    poetry publish --build -r testpypi
    
    poetry publish --build -r pypi