I have this HC-05 Bluetooth module that works quite well and it supports changing its class type, I wondered if it was possible to change it so that it would register as an audio output so I could stream my phone sound to it and then use an H-bridge as a D class amplifier as output (I don’t care about quality).
I used this generator to get the right Bluetooth class type (0x20041C), this is also consistent with a similar Raspberry Pi project. I’m absolutely positive the new class has been set as “AT+CLASS?” command returns “20041c” as expected.
Unfortunately when I pair the Android phone with the HC-05 Bluetooth module my phone doesn’t show “use as audio output” service, as if it didn’t recognise it right, maybe I’m missing some other protocol here, should the Bluetooth module reply or broadcast something? Maybe it’s completely impossible, I don’t have a clue and Google hasn’t been much of use.
If anybody has some experience could you point me to the right documentation/similar projects on how to implement sound over Bluetooth at this low level?