cVc with FSC-BT1026D

engiadina

Working on a HFP application I wonder if cVc is available for audio via I2S.

If yes, how to activate it.

Thanks for help,
engiadina

FAE_Gavin

engiadina Thank you for reaching out to us on the forum.

To help us better understand and solve your issue efficiently when we return, please provide the following information if applicable:

Device model(s)
Firmware version (can be found via Feasyblue App)
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Mobile device model & OS version (e.g., iPhone 15, iOS 18; Samsung S24, Android 15)
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FAE_Gavin

engiadina The FSC‑BT1026D supports cVc by default for HFP. No special activation is needed.

engiadina

Hi,

we are using our own app, which transfers voice via S2M interface to the FSC BT-1026D module. The app itself uses some sound module based on the chip SGTL5000-Stereo-Codec with an external microphone and speaker.

Now when we use this setup a handsfree for a phone call, there is some serious echo. We have the hope that cVc could help us but we could not see any kind of echo suppression.

FAE_Gavin

engiadina Thank you for your patience. After discussing the echo issue you're experiencing with the I2S audio path on the FSC‑BT1026D，here is the feedback from our R&D team:

Currently, the echo cancellation performance on the I2S input path of the FSC‑BT1026D is relatively poor, and we have no extra R&D resources available for optimization right now.
We strongly recommend using the module's analog microphone input interface together with the built‑in cVc echo cancellation. This path has been thoroughly tested and performs very well for hands‑free applications.
If your design must use I2S input, an alternative is to implement echo cancellation on the SGTL5000 codec side. Some external codecs offer built‑in echo cancellation features, or you could process the audio in your host system before sending it to the module.

engiadina

Our application actually uses two modes:

One mode is to use a handset which is producing voice data in digital form. Our application handles this data, converts it to I2S and sends it over to the BT module. This part works fine, no cVc needed.

The second mode would be handsfree mode, where we have a microphone and speaker. When I connect those directly to the FSC1026D cVc works om so far.

Problem is changing those modes without interrupting the BT connection. When we tested that, the connection to the external BT device (i.e. iPhone) gets interrupted which is not acceptable.

So we need a way to change the audio mode seamlessly or find a different solution.

FAE_Gavin

engiadina In the current firmware, the audio path configuration (I2S vs analog) is set via the AT+I2SCFG command. However, this command requires a module reboot to take effect. This reboot inevitably disconnects the Bluetooth connection.

Because of this design, dynamic (live) switching between I2S and analog without breaking the Bluetooth link is not supported in the standard firmware.

If your application absolutely needs seamless switching while maintaining the Bluetooth connection, this would require a custom firmware modification – specifically, altering the audio routing mechanism to allow real‑time switching without a reboot.

We recommend contacting our sales team to discuss the feasibility and lead time for a custom firmware that meets your requirement.