BC 127 Control smartphone <-> BC127 <-> motorbike intercom

I have discovered the BC127 a few days ago and start to learn melody basic commands, profiles, pairing, all with good results.

I explain my project:


  • Smartphone (ANDROID or IOS)
  • motorbike intercom BT4.2 (HFP/A2DP/AVRCP profiles)
  • BC127 module

I want control music and calls from smartphone through the BC127 module and hear and speak through the intercom.
The BC127 is connected with a MCU (teensy 4.0) via UART.

Now, from what I have read, i have understood (maybe) that i need two BC127 connected to each other via I2S pins and each module control smartphone and intercom or can I do it in another simpler way ?

Can anyone guide me on the right way ? because I’m a bit confused.
is it right what I have written above?

Hi @massimino.andrea,
Following your information, the topology will be like below
As you said, need to have 2 BC127 connect each other via I2S interface, one BC127 will connect to the smartphone and the other will connect to the headset.
You can refer to the document for more configuration detail
Please share any concerns you have. Help us tick Solution if your question is answered

1 Like

Thanks for your reply.

Today arrived 2 bc127 ready to test in the above configuration.

Can you confirm me the hardware I2S connections?

master ------------------------- slave

45 (SPI_PCM) ------ to GND ----- 45 (SPI_PCM)
46 (PCM1_SYNC) --------------- 46 (PCM1_SYNC)
47 (PCM1_CLK) ----------------- 47 (PCM1_CLK)
48 (PCM1_OUT) ----------------- 49 (PCM1_IN)
49 (PCM1_IN) ------------------- 48 (PCM1_OUT)

on software side (Digital Audio Configuration ):
SET AUDIO_DIGITAL=0 44100 64 100A00 // MASTER
SET AUDIO_DIGITAL=0 44100 64 100200 // SLAVE

Are the hardware / software configurations listed above correct?

Finally, Do I need to manual redirect the ROUTE (Audio Routing) or can I leave the automatic settings?


Hi @massimino.andrea,
Software configuration seems good with master and slave. I’m not sure about MCU (teensy 4.0) but you can try with that configuration


So you cannot create a bi direction audio connection between two BC127’s because the audio profile that supports this (HFP) requires a call control system to be implemented which it expects to come from a handset that is connected and it will then take that audio stream and either route it over to another BT device or it can be used on one of the BC127’s audio interfaces.




:confused: :thinking:

What can be the right solution?


Generically speaking unless you have some form of call control in a given BT unit, and this is built around the HFP working with a handset which has the ability to actually place phone calls, then there isn’t really an easy way to do this as its not what the normal use cases of BT are designed to do.



Hi Andrea,
you can contact Acal BFi Italy (Communication division ask for Elisabetta or Luca) for native language support with SiW local FAE.
have a great day!
Will be more than happy to support.