// SampleBuffferInitI2S
//
// Do the initial setup required if we're going to capture the audio with I2S
//i2s number
#define EXAMPLE_I2S_NUM (I2S_NUM_0)
//i2s sample rate
#define EXAMPLE_I2S_SAMPLE_BITS (I2S_COMM_FORMAT_I2S | I2S_COMM_FORMAT_I2S_MSB)
//enable display buffer for debug
#define EXAMPLE_I2S_BUF_DEBUG (0)
//I2S read buffer length
#define EXAMPLE_I2S_READ_LEN (MAX_SAMPLES)
//I2S built-in ADC unit
#define I2S_ADC_UNIT ADC_UNIT_1
//I2S built-in ADC channel
#define I2S_ADC_CHANNEL ADC1_CHANNEL_0
//flash record size, for recording 5 second
void SampleBufferInitI2S()
{
i2s_config_t i2s_config;
i2s_config.mode = (i2s_mode_t)(I2S_MODE_MASTER | I2S_MODE_RX | I2S_MODE_ADC_BUILT_IN);
i2s_config.sample_rate = SAMPLING_FREQUENCY;
i2s_config.dma_buf_len = MAX_SAMPLES;
i2s_config.bits_per_sample = I2S_BITS_PER_SAMPLE_16BIT;
i2s_config.channel_format = I2S_CHANNEL_FMT_ONLY_LEFT;
i2s_config.use_apll = false,
i2s_config.communication_format = I2S_COMM_FORMAT_I2S_MSB;
i2s_config.intr_alloc_flags = ESP_INTR_FLAG_LEVEL1;
i2s_config.dma_buf_count = 2;
//install and start i2s driver
ESP_ERROR_CHECK( adc_gpio_init(ADC_UNIT_1, ADC_CHANNEL_0) );
ESP_ERROR_CHECK( i2s_driver_install(EXAMPLE_I2S_NUM, &i2s_config, 0, NULL) );
ESP_ERROR_CHECK( i2s_set_adc_mode(I2S_ADC_UNIT, I2S_ADC_CHANNEL) );
}
void FillBufferI2S()
{
uint16_t byteBuffer[MAX_SAMPLES];
if (IsBufferFull())
{
Serial.printf("BUG: FillBUfferI2S found buffer already full.");
return;
}
size_t bytesRead = 0;
ESP_ERROR_CHECK( i2s_adc_enable(EXAMPLE_I2S_NUM) );
ESP_ERROR_CHECK( i2s_read(EXAMPLE_I2S_NUM, (void*) byteBuffer, sizeof(byteBuffer), &bytesRead, portMAX_DELAY) );
ESP_ERROR_CHECK( i2s_adc_disable(EXAMPLE_I2S_NUM) );
_cSamples = _MaxSamples;
if (bytesRead != sizeof(byteBuffer))
{
Serial.printf("Could only read %u byttes of %u in FillBufferI2S()\n", bytesRead, sizeof(byteBuffer));
return;
}
for (int i = 0; i < ARRAYSIZE(byteBuffer); i++)
{
_vReal[i] = byteBuffer[i];
}
Serial.println("");
//for (int i = 0; i < 128; i++)
// Serial.printf("%d, %f\n", i, _vReal[i]);
_cSamples = MAX_SAMPLES;
}
Need to try this (from Reddit): ADC configured as an I2S peripheral that writes directly to system memory (DMA). https://www.reddit.com/r/esp32/comments/bid08m/finally_got_audio_sampling_via_dma_with_no_cpu/