For my project, I need to build circuitry with a mic array of 6 MEMS mics. My mic circuit for two mics is given below. Please help me in building this circuitry thanks in advance.
Hi @Reventh
The APQ8016 processor chip on the Dragonboard 410c only has one DMIC input. Ecah DMIC input
can support a pair of digital microphones and your diagram for connecting two microphones is correct. If you look at the 96Boards Audio Mezzanine schematic you will see the actual connections for the first DMIC.
The APQ8016/PM8916 chipset also supports direct connection of up to 3 analog microphones. This brings you up to 5 total microphones, but still one shy of your desired 6 microphones.
The only way to get 6 channel audio into the processor is through the MI2S interface. This will of course require additional circuitry to convert the DMIC outputs to I2S format.
Sorry, I don’t see an easy way to attach 6 mics to the DragonBoard 410c.
-Lawrence-
@ljking Thanks you! Any additional microprocessor will be required be convert DMIC outputs to I2S format?
Something like a pcm1865 can do the job. Each one can handle a total of 4 channels, you can hook 2 pcm1865’s to the same mi2s in TDM mode to achieve up to 8 channels.
But to be honest, you would probably have an easier time with a usb peripheral.
Direct-to-I2S mems devices such as SPH0645LM4H might be worth a look too.
@ljking Could you please provide me the connections to connect 3 analog mics directly to 410c board.
You’ve got two of them already on your audio mezz (one surface mount analog microphone, and one on the jack). The third one is attached to an unpopulated footprint on the back of the db410c labeled “GM1” – look at page 20 of the db410c schematic. Look at page 30 of the schematic to see where the two other microphone signals are connected to the audio header, which is what you are using with the audio mezz.
