I2S ADC Advice for RPI

[mbt28]

Hello,

I am in the last stage of integrating LIVI into BMW IBUS navigation systems. I am designing a hat which can connect to OEM microphone. Problem arises when existing I2S ADC boards requires master clock, RPI cannot provide it. So instead I set RPI as I2S slave and provide master clock externally to PCM1808.

What kind of audio ADC are you using in your projects? Would you suggest me a codec which doesnt require I2S master clock? Preferably with audio output and microphone bias voltage.

Another issue is, most of the radio units have MUTE, and TEL GPIO pins to mute the radio and enable telephone. Is it possible to assign some GPIO pins for LIVI or provide an API to read call status?

Thanks

[mbt28]

I set PCM1808 as master with 12.288mhz crystal, and added max4466 electrelet microphone amplifier. I am able get clear audio input from OEM BMW Microphone.

You can find the driver and details from here: https://github.com/mbt28/RPI-PCM1808-MIC

**Some prototyping examples:

Get a board like this with on board crystal + get an electrelet microphone amplifier board and test it with your microphone.

If you have board like this, set the PCM1808 as master, add your active crystal output as master clock. Then you need an electrelet microphone amplifier.