void setupI2S() {
  i2s_config_t cfg = {
    .mode                 = i2s_mode_t(I2S_MODE_MASTER | I2S_MODE_TX),
    .sample_rate          = SAMPLE_RATE,
    .bits_per_sample      = I2S_BITS_PER_SAMPLE_16BIT,
    .channel_format       = I2S_CHANNEL_FMT_RIGHT_LEFT,
    .communication_format = I2S_COMM_FORMAT_I2S,
    .intr_alloc_flags     = ESP_INTR_FLAG_LEVEL1,
    .dma_buf_count        = DMA_BUF_COUNT,
    .dma_buf_len          = DMA_BUF_LEN,
    .use_apll             = true,
    .tx_desc_auto_clear   = false
  };
  i2s_pin_config_t pins = {
    .bck_io_num   = I2S_BCLK_PIN,
    .ws_io_num    = I2S_LRC_PIN,
    .data_out_num = I2S_DOUT_PIN,
    .data_in_num  = I2S_PIN_NO_CHANGE
  };
  i2s_driver_install(I2S_PORT, &cfg, 0, nullptr);
  i2s_set_pin(I2S_PORT, &pins);
  i2s_set_clk(I2S_PORT, SAMPLE_RATE, I2S_BITS_PER_SAMPLE_16BIT, I2S_CHANNEL_STEREO);
  i2s_zero_dma_buffer(I2S_PORT);
  i2s_start(I2S_PORT);
  logMsg("[I2S] ready");
}