　時間潰しに丁度良いお値段だったのでアマゾンで購入し使ってみました。（盗聴に御注意ください）

　今回の構成は以下になります。

０．Arduino IDE 2.3.2
１．INMP441 全方向性マイクモジュール I2SインターフェースMEMS高精度低電力デュポンケーブル付き
２．ESP32-WROVER-KEY,　Chip is ESP32-D0WD-V3 (revision v3.0),　Flash 8MB, MicroFan製

接続は標準的なものにしました。

マイクモジュール	ESP32
SCK	32
SD	33
WS	25
L/R	GND
VDD	3V3
GND	GND

まず次のサイト内の "INMP441 Microphone Module Code" を試してみました。

しかし、何度やり直してもダメ。配線も色々変えてみました。凄いノイズでしたが、音を立てると一瞬ノイズが消えます。なんじゃこれと思いました。でも動作はしてるということ？そんな中もう一つのサイトを見つけました。

ここにはモジュール表面の「金縁」部分にハンダを載せるなとありました。そこで不用意に載せたままだったハンダを取り除き再度挑戦、正常に音を拾っているようです。そこでさらに上記サイトのスケッチを試してみました。いくつかコンパイルエラーになる個所を修正した結果、無事にVLCメディアプレイヤーを使いネットワークストリームとして再生出来ました。感激です。次が修正したinoファイルです。

ESP_INMP441_WebSteream.ino

#include <driver/i2s.h>
#include <SPIFFS.h>
#include <WiFi.h>
#include <WebServer.h>  // Changed from <ESP32WebServer.h>
#include <ESPmDNS.h>
#include <FS.h>

#include "EspEasySerialCommand.h" // For using Serial.Printf()

WebServer webserver(80);
const char* ssid = "Your SSID";
const char* password = "Your PASSWORD";

IPAddress local_IP(192, 168, 0, 250);
IPAddress gateway(192, 168, 0, 1);
IPAddress subnet(255, 255, 255, 0);

const char common_name[40] = "inmp441test";
const char* mdnsName = common_name;
#define BUFFER_SIZE 16384
uint8_t buf[BUFFER_SIZE];

#define I2S_WS 25
#define I2S_SD 33
#define I2S_SCK 32
#define I2S_PORT I2S_NUM_0
#define I2S_SAMPLE_RATE (16000)
#define I2S_SAMPLE_BITS (16)
#define I2S_READ_LEN (16 * 1024)
#define RECORD_TIME (30)  // 秒
#define I2S_CHANNEL_NUM (1)
#define FLASH_RECORD_SIZE (I2S_CHANNEL_NUM * I2S_SAMPLE_RATE * I2S_SAMPLE_BITS / 8 * RECORD_TIME)

File spiffs_file;
const char fname[] = "/recording.wav";
const int headerSize = 44;

void setup() {
  Serial.begin(115200);
  SPIFFSInit();
  i2sInit();
  xTaskCreate(i2s_adc, "i2s_adc", 1024 * 3, NULL, 1, NULL);

  startWiFi();
  startMDNS();
  startServer();
}

void loop() {
  webserver.handleClient();
}

void startWiFi() {
  WiFi.disconnect();

  // if (!WiFi.config(local_IP, gateway, subnet, primaryDNS, secondaryDNS)) {
  if (!WiFi.config(local_IP, gateway, subnet)) {
    Serial.println("STA Failed to configure");
  }
  // WiFi.softAP(ssid, password);
  WiFi.mode(WIFI_STA);
  WiFi.begin(ssid, password);
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }
  Serial.println("");
  Serial.print("SSID \"");
  Serial.print(ssid);
  Serial.println("\" started\r\n");

  Serial.print("Connected to ");
  Serial.println(ssid);

  Serial.print("IP address: ");
  Serial.println(WiFi.localIP());

  Serial.println("");
}

void startMDNS() {
  MDNS.begin(mdnsName);
  Serial.print("mDNS responder started: http://");
  Serial.print(mdnsName);
  Serial.println(".local");
}

void startServer() {
  webserver.on("/", handleRoot);
  webserver.on(
    "/edit.html", HTTP_POST, []() {
      webserver.send(200, "text/plain", "");
    },
    handleFileUpload);

  webserver.onNotFound(handleNotFound);

  webserver.begin();
  Serial.println("HTTP webserver started.");
}

void handleNotFound() {
  if (!handleFileRead(webserver.uri())) {
    webserver.send(404, "text/plain", "404: File Not Found");
  }
}

bool handleFileRead(String path) {
  Serial.println("handleFileRead: " + path);
  if (path.endsWith("/")) path += "index.html";
  String contentType = getContentType(path);
  String pathWithGz = path + ".gz";
  if (SPIFFS.exists(pathWithGz) || SPIFFS.exists(path)) {
    if (SPIFFS.exists(pathWithGz))
      path += ".gz";
    File spiffs_file = SPIFFS.open(path, "r");
    size_t sent = webserver.streamFile(spiffs_file, contentType);
    spiffs_file.close();
    Serial.println(String("\tSent spiffs_file: ") + path);
    return true;
  }
  Serial.println(String("\tFile Not Found: ") + path);
  return false;
}

void handleRoot() {
  Serial.println("Access");
  char message[20];
  String(webserver.arg(0)).toCharArray(message, 20);
  webserver.send(200, "text/html", (char*)buf);
}

void handleFileUpload() {
  HTTPUpload upload = webserver.upload();
  String path;
  if (upload.status == UPLOAD_FILE_START) {
    path = upload.filename;
    if (!path.startsWith("/")) path = "/" + path;
    if (!path.endsWith(".gz")) {
      String pathWithGz = path + ".gz";
      if (SPIFFS.exists(pathWithGz))
        SPIFFS.remove(pathWithGz);
    }
    Serial.print("handleFileUpload Name: ");
    Serial.println(path);
    spiffs_file = SPIFFS.open(path, "w");
    path = String();
  } else if (upload.status == UPLOAD_FILE_WRITE) {
    if (spiffs_file)
      spiffs_file.write(upload.buf, upload.currentSize);
  } else if (upload.status == UPLOAD_FILE_END) {
    if (spiffs_file) {
      spiffs_file.close();
      Serial.print("handleFileUpload Size: ");
      Serial.println(upload.totalSize);
      webserver.sendHeader("Location", "/success.html");
      webserver.send(303);
    } else {
      webserver.send(500, "text/plain", "500: couldn't create spiffs_file");
    }
  }
}

String formatBytes(size_t bytes) {
  if (bytes < 1024) {
    return String(bytes) + "B";
  } else if (bytes < (1024 * 1024)) {
    return String(bytes / 1024.0) + "KB";
  } else if (bytes < (1024 * 1024 * 1024)) {
    return String(bytes / 1024.0 / 1024.0) + "MB";
  }
}

String getContentType(String fname) {
  if (fname.endsWith(".html")) return "text/html";
  else if (fname.endsWith(".css")) return "text/css";
  else if (fname.endsWith(".json")) return "text/css";
  else if (fname.endsWith(".js")) return "application/javascript";
  else if (fname.endsWith(".ico")) return "image/x-icon";
  else if (fname.endsWith(".png")) return "image/x-icon";
  else if (fname.endsWith(".gz")) return "application/x-gzip";
  return "text/plain";
}
void SPIFFSInit() {
  if (!SPIFFS.begin(true)) {
    Serial.println("SPIFFS initialisation failed!");
    while (1) yield();
  }
  SPIFFS.remove("/test.wav");
  SPIFFS.remove(fname);
  spiffs_file = SPIFFS.open(fname, FILE_WRITE);
  if (!spiffs_file) {
    Serial.println("File is not available!");
  }

  byte header[headerSize];
  wavHeader(header, FLASH_RECORD_SIZE);

  spiffs_file.write(header, headerSize);
  listSPIFFS();
}

void i2sInit() {
  esp_err_t err;
  i2s_config_t i2s_config = {
    .mode = (i2s_mode_t)(I2S_MODE_MASTER | I2S_MODE_RX),
    .sample_rate = I2S_SAMPLE_RATE,
    .bits_per_sample = i2s_bits_per_sample_t(I2S_SAMPLE_BITS),
    .channel_format = I2S_CHANNEL_FMT_ONLY_LEFT,
    .communication_format = i2s_comm_format_t(I2S_COMM_FORMAT_STAND_I2S | I2S_COMM_FORMAT_STAND_MSB),
    .intr_alloc_flags = 0,
    .dma_buf_count = 8,
    .dma_buf_len = 1024,
    .use_apll = 1
  };

  err = i2s_driver_install(I2S_PORT, &i2s_config, 0, NULL);
  if (err != ESP_OK) {
    Serial.println("Failed to install driver");
  } else {
    Serial.println("Installed driver");
  }

  const i2s_pin_config_t pin_config = {
    .bck_io_num = I2S_SCK,
    .ws_io_num = I2S_WS,
    .data_out_num = -1,
    .data_in_num = I2S_SD
  };

  err = i2s_set_pin(I2S_PORT, &pin_config);
  if (err != ESP_OK) {
    Serial.println("Failed to install pin");
  } else {
    Serial.println("Installed pin");
  }
}

void i2s_adc_data_scale(uint8_t* d_buff, uint8_t* s_buff, uint32_t len) {
  uint32_t j = 0;
  uint32_t dac_value = 0;
  for (int i = 0; i < len; i += 2) {
    dac_value = ((((uint16_t)(s_buff[i + 1] & 0xf) << 8) | ((s_buff[i + 0]))));
    d_buff[j++] = 0;
    d_buff[j++] = dac_value * 256 / 2048;
  }
}

void i2s_adc(void* arg) {
  // i2s_start(I2S_PORT);
  int i2s_read_len = I2S_READ_LEN;
  int flash_wr_size = 0;
  size_t bytes_read;

  char* i2s_read_buff = (char*)calloc(i2s_read_len, sizeof(char));
  uint8_t* flash_write_buff = (uint8_t*)calloc(i2s_read_len, sizeof(char));

  i2s_read(I2S_PORT, (void*)i2s_read_buff, i2s_read_len, &bytes_read, portMAX_DELAY);
  i2s_read(I2S_PORT, (void*)i2s_read_buff, i2s_read_len, &bytes_read, portMAX_DELAY);

  Serial.println(" *** Recording Start *** ");
  while (flash_wr_size < FLASH_RECORD_SIZE) {
    //read data from I2S bus, in this case, from ADC.
    i2s_read(I2S_PORT, (void*)i2s_read_buff, i2s_read_len, &bytes_read, portMAX_DELAY);
    //example_disp_buf((uint8_t*) i2s_read_buff, 64);
    //save original data from I2S(ADC) into flash.
    i2s_adc_data_scale(flash_write_buff, (uint8_t*)i2s_read_buff, i2s_read_len);
    spiffs_file.write((const byte*)flash_write_buff, i2s_read_len);
    flash_wr_size += i2s_read_len;

    //ets_printf("Sound recording %u%%\n", flash_wr_size * 100 / FLASH_RECORD_SIZE);
    //ets_printf("Never Used Stack Size: %u\n", uxTaskGetStackHighWaterMark(NULL));
    Serial.printf("Sound recording %u%%\n", flash_wr_size * 100 / FLASH_RECORD_SIZE);
    Serial.printf("Never Used Stack Size: %u\n", uxTaskGetStackHighWaterMark(NULL));
  }
  spiffs_file.close();

  free(i2s_read_buff);
  i2s_read_buff = NULL;
  free(flash_write_buff);
  flash_write_buff = NULL;
  listSPIFFS();
  // i2s_stop(I2S_PORT);
  vTaskDelete(NULL);
}

void example_disp_buf(uint8_t* buf, int length) {
  printf("======\n");
  for (int i = 0; i < length; i++) {
    printf("%02x ", buf[i]);
    if ((i + 1) % 8 == 0) {
      printf("\n");
    }
  }
  printf("======\n");
}

void wavHeader(byte* header, int wavSize) {
  header[0] = 'R';
  header[1] = 'I';
  header[2] = 'F';
  header[3] = 'F';
  unsigned int fileSize = wavSize + headerSize - 8;
  header[4] = (byte)(fileSize & 0xFF);
  header[5] = (byte)((fileSize >> 8) & 0xFF);
  header[6] = (byte)((fileSize >> 16) & 0xFF);
  header[7] = (byte)((fileSize >> 24) & 0xFF);
  header[8] = 'W';
  header[9] = 'A';
  header[10] = 'V';
  header[11] = 'E';
  header[12] = 'f';
  header[13] = 'm';
  header[14] = 't';
  header[15] = ' ';
  header[16] = 0x10;
  header[17] = 0x00;
  header[18] = 0x00;
  header[19] = 0x00;
  header[20] = 0x01;
  header[21] = 0x00;
  header[22] = 0x01;
  header[23] = 0x00;
  header[24] = 0x80;
  header[25] = 0x3E;
  header[26] = 0x00;
  header[27] = 0x00;
  header[28] = 0x00;
  header[29] = 0x7D;
  header[30] = 0x00;
  header[31] = 0x00;
  header[32] = 0x02;
  header[33] = 0x00;
  header[34] = 0x10;
  header[35] = 0x00;
  header[36] = 'd';
  header[37] = 'a';
  header[38] = 't';
  header[39] = 'a';
  header[40] = (byte)(wavSize & 0xFF);
  header[41] = (byte)((wavSize >> 8) & 0xFF);
  header[42] = (byte)((wavSize >> 16) & 0xFF);
  header[43] = (byte)((wavSize >> 24) & 0xFF);
}

void listSPIFFS(void) {
  Serial.println(F("\r\nListing SPIFFS files:"));
  static const char line[] PROGMEM = "=================================================";

  Serial.println(FPSTR(line));
  Serial.println(F(" File name               Size"));
  Serial.println(FPSTR(line));

  fs::File root = SPIFFS.open("/");
  if (!root) {
    Serial.println(F("Failed to open directory"));
    return;
  }
  if (!root.isDirectory()) {
    Serial.println(F("Not a directory"));
    return;
  }

  fs::File file = root.openNextFile();
  while (file) {
    if (file.isDirectory()) {
      Serial.print("DIR : ");
      String fileName = file.name();
      Serial.print(fileName);
    } else {
      String fileName = file.name();
      Serial.print(" " + fileName);
      // File path can be 31 characters maximum in SPIFFS
      int spaces = 33 - fileName.length();  // Tabulate nicely
      if (spaces < 1) spaces = 1;
      while (spaces--) Serial.print(" ");
      String fileSize = (String)file.size();
      spaces = 10 - fileSize.length();  // Tabulate nicely
      if (spaces < 1) spaces = 1;
      while (spaces--) Serial.print(" ");
      Serial.println(fileSize + " bytes");
    }

    file = root.openNextFile();
  }

  Serial.println(FPSTR(line));
  Serial.println();
  delay(1000);
}

　次はSDカードに保存ですかね。気が向きましたら。最後まで見ていただきありがとうございました。