Stereo ICS-43434 MEMS mic configuration

[alw1746]

I have 2 Adafruit 24-bit ICS-43434 MEMS mics and wired them in stereo as per the TDK ICS-43434 datasheet. But I wasn't sure how to configure them in AudioInfo so here's a simple sketch to experiment with the channel and bit settings. The configs that worked are:

1. AudioInfo info(44100, 1, 16); //left mic only.
   This is a mono config and L-mic output to L-speaker only. Do not connect R-mic, you will get noise and reduced volume on speakers.

2. AudioInfo info(44100, 2, 16); //left or right mic.
   This is a mono config and L or R mic will output to L or R speaker. Do not connect both mics, you will get noise and reduced volume speakers.

3. AudioInfo info(44100, 2, 32); //left+right(stereo) mics.
   This is a stereo config and L-R mics will output to L-R speakers respectively.

I can also confirm the Adafruit PCM5102 DAC does not need extra solder bridging(like XSMT for HiLetgo). It worked with just the 3V,GND and 3 I2S pins.

Sketch

#include "AudioTools.h"

//AudioInfo info(44100, 1, 16);       //left mic only.
//AudioInfo info(44100, 2, 16);       //left or right mic.
AudioInfo info(44100, 2, 32);       //left+right(stereo) mics.
I2SStream in;          //2 x ICS-43434 24-bit I2S MEMS mic
I2SStream out;         //PCM5102 DAC
StreamCopy copier(out, in);

void setup(void) {  
  Serial.begin(115200);
  // change to Warning to improve the quality
  AudioToolsLogger.begin(Serial, AudioToolsLogLevel::Warning); 
 
  // start I2S in
  auto config_in = in.defaultConfig(RX_MODE);
  config_in.copyFrom(info); 
  config_in.i2s_format = I2S_STD_FORMAT;
  config_in.is_master = true;
  config_in.port_no = 0;
  config_in.pin_bck = 2;
  config_in.pin_ws = 4;
  config_in.pin_data = 3;
  in.begin(config_in);

  // start I2S out
  auto config_out = out.defaultConfig(TX_MODE);
  config_out.copyFrom(info); 
  config_out.i2s_format = I2S_STD_FORMAT;
  config_out.is_master = true;
  config_out.port_no = 1;
  config_out.pin_bck = 8;
  config_out.pin_ws = 10;
  config_out.pin_data = 9;
  out.begin(config_out);
}

void loop() {
  copier.copy();    //runs on core 1
}

[pschatzmann]

Just one more piece of information: for mono you can select the ouput channel with config_out.channel_format. e.g. config_out.channel_format = I2SChannelSelect::RIGHT;

To use 2 microphones might be tricky, but the following should work:

• Use both I2S in stereo mode.
• Use one of them in duplex mode to read from a mic and also output the signal (RXTX_MODE)
• Use InputMerge to merge both mics into a stream with 4 channels (from both I2SStreams) chained by a ChannelSelectOutput to generate a stereo signal (e.g. by selecting channel 0 and 2).

For the last step, you could also implement your custom logic: e.g. using a CallbackStream.