Designing BT Module for A2DP Source & Mono Audio Sink

Thread Starter


Joined Nov 19, 2012
I'm looking to design a circuit that would be a Bluetooth adapter for my motorcycle's Stereo output and Mono Mic input (for a CB). The motorcycle provides 5 pins for line level signals: Output Audio (L,R,C) and Input Mic (Gnd, Data). The bike also has a momentary PTT that can provide a trigger voltage, if needed for the design.

I'm just learning about the Bluetooth Profiles, etc. and would appreciate any guiding advice on how to approach designing (learning to design) this type of circuit. If a viable approach could be outlined, I would then be able to learn what's necessary to make the design.

The design would need to do the following:
  1. Connect to Bluetooth 4.2 Headset (Stereo Speakers and Mono Microphone) (simultaneously?)
  2. Transmit Stereo Audio from the bike AudioOut to the BT Headset Stereo Speakers
  3. Receive Mono Audio from the BT Headset Microphone to the bike MicInput for the CB
  4. These modes COULD be switched based on a PTT (momentary switch) voltage signal from the bike.

  1. Can the A2DP-Source and the Mono-Sink occur simultaneously while connected to the Headset?
    1. Would this state be similar to being on a 'phone call'? Draining the headset battery?
  2. Can the design use the PTT to quickly switch between transmitting the stereo audio and receiving the mono audio?
    1. If so, can this switching occur quickly based on the PTT?
  3. Which design approach would be easier: dedicated MCU/code or Raspberry Pi

My headset is a Sena 20s and does not support AptX, but connects seamlessly with phones, PCs, etc. to produce the desired functions: RX Stereo Audio & TX Mono Mic.

Thank you up front for reading and providing feedback. While I'm a little experienced with Arduino, ESP32, etc. I've not delved into the bluetooth foundations.... please be gentle.