Real-time Audio Monitoring with AtomS3U

[Etherist]

Hi,

I would like to use the AtomS3U to behave as a wireless real-time audio broadcaster. I have seen that the ESP-32S3 is capable of doing this with an IMP441 using a node server (see here), but haven't had success using the AtomS3U's onboard PDM.

I've attached my code, which is mostly a modified version of the program written by ThatProject in the linked YouTube video. I've also incorporated some code from the PDM unit Arduino example by M5Stack (see here).

So far, I am able to run the server and establish connection to the AtomS3U, however, when I try and stream the audio, I either get static noise, or nothing at all.

#include <driver/i2s.h>
#include <WiFi.h>
#include <ArduinoWebsockets.h>

#define I2S_SD 38
#define I2S_SCK 39
#define I2S_PORT I2S_NUM_0

#define bufferCnt 2
#define bufferLen 128
int16_t sBuffer[bufferLen];

const char* ssid = "spider_gateway";
const char* password = "TMTspider1";

const char* websocket_server_host = "192.168.24.246";
const uint16_t websocket_server_port = 8888;  // <WEBSOCKET_SERVER_PORT>

using namespace websockets;
WebsocketsClient client;
bool isWebSocketConnected;

void onEventsCallback(WebsocketsEvent event, String data) {
  if (event == WebsocketsEvent::ConnectionOpened) {
    Serial.println("Connnection Opened");
    isWebSocketConnected = true;
  } else if (event == WebsocketsEvent::ConnectionClosed) {
    Serial.println("Connnection Closed");
    isWebSocketConnected = false;
  } else if (event == WebsocketsEvent::GotPing) {
    Serial.println("Got a Ping!");
  } else if (event == WebsocketsEvent::GotPong) {
    Serial.println("Got a Pong!");
  }
}

void i2s_install() {
  // Set up I2S Processor configuration
  const i2s_config_t i2s_config = {
    .mode = (i2s_mode_t)(I2S_MODE_MASTER | I2S_MODE_RX | I2S_MODE_PDM),
    .sample_rate = 44100,
    .bits_per_sample = I2S_BITS_PER_SAMPLE_16BIT, // is fixed at 12bit, stereo, MSB
    .channel_format = I2S_CHANNEL_FMT_ONLY_RIGHT,
    .communication_format = I2S_COMM_FORMAT_I2S,
    .intr_alloc_flags = ESP_INTR_FLAG_LEVEL1,
    .dma_buf_count = bufferCnt,
    .dma_buf_len = bufferLen,
  };

  i2s_driver_install(I2S_PORT, &i2s_config, 0, NULL);
}

void i2s_setpin() {
  // Set I2S pin configuration
  const i2s_pin_config_t pin_config = {
    .bck_io_num = I2S_PIN_NO_CHANGE,
    .ws_io_num  = I2S_SCK,
    .data_out_num = I2S_PIN_NO_CHANGE,
    .data_in_num = I2S_SD,
  };

  i2s_set_pin(I2S_PORT, &pin_config);
  //Serial.println("Init i2s_set_clk");
  i2s_set_clk(I2S_PORT, 44100, I2S_BITS_PER_SAMPLE_16BIT, I2S_CHANNEL_MONO);
}

void setup() {
  Serial.begin(115200);

  connectWiFi();
  connectWSServer();
  xTaskCreatePinnedToCore(micTask, "micTask", 10000, NULL, 1, NULL, 1);
}

void loop() {
}

void connectWiFi() {
  WiFi.begin(ssid, password);

  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
  }
  Serial.println("");
  Serial.println("WiFi connected");
}

void connectWSServer() {
  client.onEvent(onEventsCallback);
  while (!client.connect(websocket_server_host, websocket_server_port, "/")) {
    delay(500);
    Serial.print(".");
  }
  Serial.println("Websocket Connected!");
}


void micTask(void* parameter) {

  i2s_install();
  i2s_setpin();
  i2s_start(I2S_PORT);

  size_t bytesIn = 0;
  while (1) {
    esp_err_t result = i2s_read(I2S_PORT, &sBuffer, bufferLen, &bytesIn, portMAX_DELAY);
    if (result == ESP_OK && isWebSocketConnected) {
      client.sendBinary((const char*)sBuffer, bytesIn);
    }
  }
}

Thanks in advance for any tips.