BC127 half-duplex issue in telephony

IoT Modules WiFi and Bluetooth Modules
1

Hi Sierra team,

I encountered an critical issue during a phone call (HFP) using the BC127 module.

Sometimes quickly after the start of the call, the communication goes from full-duplex to half-duplex i.e. when other people are talking they are not able to hear my voice anymore and I cannot interrupt them.

I tried several tests and it appears that this is cause by the bluetooth chipset itself : I am using CVC algorithm on this platform. I disabled almost all blocks in CVC processing but the problem remains. Still it is sometimes hard to reproduce. Have you ever had this kind of problem ? I would really appreciate your support.

Please find below my melody version and config.

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2

@ericbenhaim

Generically speaking half duplex is not an issue that has been reported to us and the 7.3 firmware has been our for 3 years or so, as a result it may be specific to your scenario/device.

Regards

Matt

3

Hi Matt

The BC127 board is connected to my android phone which I use to make the phone call.
During the call when I switch from BC127 to my phone I don’t have any issue.
Switching back to BC127 causes the half-duplex behavior, so I am confident the problem comes from the board configuration (or negotiation between board and phone?)
Any idea how to investigate this ?

Thanks,
Eric

4

@ericbenhaim

So to be clear what you are doing is as follows

  • Connect the BC127 with an Android phone over Bluetooth.
  • Place a call with the phone.
  • When the call is connected you have bi directional audio with the audio coming out of the BC127.
  • Switch the audio to come out of the handset, again bi directional audio.
  • Switch it back to the BC127 and it is half duplex?

Does it do this with an iPhone?

Regards

Matt

5

Hi Matt,

BC127 is used as the headset.
I already tried with several host devices and succeed to reproduce the half-duplex issue.

  • Laptop using Teams on windows 10
  • Laptop using Discord on windows 10
  • Android phone
  • iPhone

Here is the sequence :

  • Connect BC127 to host device
  • Init a call (phone call, teams meetings, …)
  • Call is connected with full-duplex in/out of the BC127
  • It happens that when the remote caller talks I can’t talk at the same time : half-duplex
  • Switch the audio to come out of the handset or laptop, again bi directional audio.
  • Switch to a bluetooth headset, still bi directional audio
  • Switch back to the BC127, it is half duplex.

Thanks,
Eric