Hi guys,
I am using the LBEE5QD1ZM module from Murata Electronics that embedded the 88W8987 chipset. At this moment I am finishing the Hands-Free implementation, but there is 1 problem/limitation that I would like to resolve.
Before describing the problem, consider the following points:
1 - I am not using the bluetooth stack provided by NXP. I using a third party stack due compatibilization between other products;
2 - My bluetooth stack is compatible with 4.2 specification, so I used the HCI_CMD_MARVELL_WRITE_COMPATIABILITY_MODE to put the module in 4.2 mode;
3 - We are using the A2DP profile with the audio through HCI interface and the HFP profile with the audio through PCM interface;
4 - My microcontroller is the host when the PCM is being using;
5 - I am using the microcontroller i.MX RT1176.
During the Hands-Free development, I noticed several times where the audio in far-end side was muted (microfone audio from my microcontroller to bluetooth controller). The audio in near-end side was always ok (audio from bluetooth controller to microcontroller playing in the product amplifier). To discart a problem in the microphone acquisition I used a logic analyzer to decode the PCM lines and I could see that my microphone acquisition was ok when the problem occurred.
After trying several different things (example, different PCM configurations) where the problem persisted, I tried to stop the PCM in microcontroller side when the problem ocurred and start again and in some times the audio started in the far-end side. Look that I did not send any different command to bluetooth controller, I just stopped and started the PCM lines. After this, I saw that there was a Wi-Fi/bluetooth firmwre update, so I updated my firmware from version "16.91.21.p64.1 to 16.91.21.p82" to "16.91.21.p124 to 16.91.21.p133". After this I did not faced the microphone problem anymore, but I started to have problem in near-end side (audio from bluetooth controller to microcontroller playing in the product amplifier). In this setup the audio came, sometimes, with noise. Again I used a logic analizer to decode de PCM lines.
The tests described above were done at 16 kHz, so, using the mSBC codec. Because my problem seemed to be related with the PCM part, I forced the use of CVSD codec through HFP features description. Running at 8 kHz with "16.91.21.p124 to 16.91.21.p133" new firmware version the problem almost stopped. I said almost because in 2 times there was just noise in both sides. Now I using the "16.91.21.p64.1 to 16.91.21.p82" old firmware version at 8 kHz and I did not faced a problem anymore.
So, my questions are:
1 - Have you ever heard about a problem like this?
2 - Is there bluetooth updates in new versions of the module firmware? The document RN00174 does not show any bluetooth update.
3 - Does the module have some limitation to use the mSBC codec?
Thanks for your attention.
Best Regards,
J. V. Melo.
