WLED/usermods/audioreactive/audio_source.h

#pragma once

#include <Wire.h>
#include "wled.h"
#include <driver/i2s.h>
#include <driver/adc.h>
#include <soc/i2s_reg.h>  // needed for SPH0465 timing workaround (classic ESP32)
#if ESP_IDF_VERSION >= ESP_IDF_VERSION_VAL(4, 4, 0)
#if !defined(CONFIG_IDF_TARGET_ESP32S2) && !defined(CONFIG_IDF_TARGET_ESP32S3) && !defined(CONFIG_IDF_TARGET_ESP32C3)
#include <driver/adc_deprecated.h>
#include <driver/adc_types_deprecated.h>
#endif
// type of i2s_config_t.SampleRate was changed from "int" to "unsigned" in IDF 4.4.x
#define SRate_t uint32_t
#else
#define SRate_t int
#endif

//#include <driver/i2s_std.h>
//#include <driver/i2s_pdm.h>
//#include <driver/i2s_tdm.h>
//#include <driver/gpio.h>

// see https://docs.espressif.com/projects/esp-idf/en/latest/esp32s3/hw-reference/chip-series-comparison.html#related-documents
// and https://docs.espressif.com/projects/esp-idf/en/latest/esp32s3/api-reference/peripherals/i2s.html#overview-of-all-modes
#if defined(CONFIG_IDF_TARGET_ESP32C2) || defined(CONFIG_IDF_TARGET_ESP32C3) || defined(CONFIG_IDF_TARGET_ESP32S2) || defined(CONFIG_IDF_TARGET_ESP32C5) || defined(CONFIG_IDF_TARGET_ESP32C6) || defined(CONFIG_IDF_TARGET_ESP32H2)
  // there are two things in these MCUs that could lead to problems with audio processing:
  // * no floating point hardware (FPU) support - FFT uses float calculations. If done in software, a strong slow-down can be expected (between 8x and 20x)
  // * single core, so FFT task might slow down other things like LED updates
  #warning This audio reactive usermod does not support ESP32-C2, ESP32-C3 or ESP32-S2.
#endif

/* ToDo: remove. ES7243 is controlled via compiler defines
   Until this configuration is moved to the webinterface
*/

// if you have problems to get your microphone work on the left channel, uncomment the following line
//#define I2S_USE_RIGHT_CHANNEL    // (experimental) define this to use right channel (digital mics only)

// Uncomment the line below to utilize ADC1 _exclusively_ for I2S sound input.
// benefit: analog mic inputs will be sampled contiously -> better response times and less "glitches"
// WARNING: this option WILL lock-up your device in case that any other analogRead() operation is performed; 
//          for example if you want to read "analog buttons"
//#define I2S_GRAB_ADC1_COMPLETELY // (experimental) continously sample analog ADC microphone. WARNING will cause analogRead() lock-up

// data type requested from the I2S driver - currently we always use 32bit
//#define I2S_USE_16BIT_SAMPLES   // (experimental) define this to request 16bit - more efficient but possibly less compatible

#ifdef I2S_USE_16BIT_SAMPLES
#define I2S_SAMPLE_RESOLUTION I2S_BITS_PER_SAMPLE_16BIT
#define I2S_datatype int16_t
#define I2S_unsigned_datatype uint16_t
#define I2S_data_size I2S_BITS_PER_CHAN_16BIT
#undef  I2S_SAMPLE_DOWNSCALE_TO_16BIT
#else
#define I2S_SAMPLE_RESOLUTION I2S_BITS_PER_SAMPLE_32BIT
//#define I2S_SAMPLE_RESOLUTION I2S_BITS_PER_SAMPLE_24BIT 
#define I2S_datatype int32_t
#define I2S_unsigned_datatype uint32_t
#define I2S_data_size I2S_BITS_PER_CHAN_32BIT
#define I2S_SAMPLE_DOWNSCALE_TO_16BIT
#endif

/* There are several (confusing) options  in IDF 4.4.x:
 * I2S_CHANNEL_FMT_RIGHT_LEFT, I2S_CHANNEL_FMT_ALL_RIGHT and I2S_CHANNEL_FMT_ALL_LEFT stands for stereo mode, which means two channels will transport different data.
 * I2S_CHANNEL_FMT_ONLY_RIGHT and I2S_CHANNEL_FMT_ONLY_LEFT they are mono mode, both channels will only transport same data.
 * I2S_CHANNEL_FMT_MULTIPLE means TDM channels, up to 16 channel will available, and they are stereo as default.
 * if you want to receive two channels, one is the actual data from microphone and another channel is suppose to receive 0, it's different data in two channels, you need to choose I2S_CHANNEL_FMT_RIGHT_LEFT in this case.
*/

#if (ESP_IDF_VERSION >= ESP_IDF_VERSION_VAL(4, 4, 0)) && (ESP_IDF_VERSION <= ESP_IDF_VERSION_VAL(4, 4, 3))
// espressif bug: only_left has no sound, left and right are swapped 
// https://github.com/espressif/esp-idf/issues/9635  I2S mic not working since 4.4 (IDFGH-8138)
// https://github.com/espressif/esp-idf/issues/8538  I2S channel selection issue? (IDFGH-6918)
// https://github.com/espressif/esp-idf/issues/6625  I2S: left/right channels are swapped for read (IDFGH-4826)
#ifdef I2S_USE_RIGHT_CHANNEL
#define I2S_MIC_CHANNEL I2S_CHANNEL_FMT_ONLY_LEFT
#define I2S_MIC_CHANNEL_TEXT "right channel only (work-around swapped channel bug in IDF 4.4)."
#else
//#define I2S_MIC_CHANNEL I2S_CHANNEL_FMT_ALL_LEFT
//#define I2S_MIC_CHANNEL I2S_CHANNEL_FMT_RIGHT_LEFT
#define I2S_MIC_CHANNEL I2S_CHANNEL_FMT_ONLY_RIGHT
#define I2S_MIC_CHANNEL_TEXT "left channel only (work-around swapped channel bug in IDF 4.4)."
#endif

#else
// not swapped
#ifdef I2S_USE_RIGHT_CHANNEL
#define I2S_MIC_CHANNEL I2S_CHANNEL_FMT_ONLY_RIGHT
#define I2S_MIC_CHANNEL_TEXT "right channel only."
#else
#define I2S_MIC_CHANNEL I2S_CHANNEL_FMT_ONLY_LEFT
#define I2S_MIC_CHANNEL_TEXT "left channel only."
#endif
#endif


/* Interface class
   AudioSource serves as base class for all microphone types
   This enables accessing all microphones with one single interface
   which simplifies the caller code
*/
class AudioSource {
  public:
    /* All public methods are virtual, so they can be overridden
       Everything but the destructor is also removed, to make sure each mic
       Implementation provides its version of this function
    */
    virtual ~AudioSource() {};

    /* Initialize
       This function needs to take care of anything that needs to be done
       before samples can be obtained from the microphone.
    */
    virtual void initialize(int8_t = I2S_PIN_NO_CHANGE, int8_t = I2S_PIN_NO_CHANGE, int8_t = I2S_PIN_NO_CHANGE, int8_t = I2S_PIN_NO_CHANGE, int8_t = I2S_PIN_NO_CHANGE, int8_t = I2S_PIN_NO_CHANGE) = 0;

    /* Deinitialize
       Release all resources and deactivate any functionality that is used
       by this microphone
    */
    virtual void deinitialize() = 0;

    /* getSamples
       Read num_samples from the microphone, and store them in the provided
       buffer
    */
    virtual void getSamples(float *buffer, uint16_t num_samples) = 0;

    /* check if the audio source driver was initialized successfully */
    virtual bool isInitialized(void) {return(_initialized);}

    /* identify Audiosource type - I2S-ADC or I2S-digital */
    typedef enum{Type_unknown=0, Type_I2SAdc=1, Type_I2SDigital=2} AudioSourceType;
    virtual AudioSourceType getType(void) {return(Type_I2SDigital);}               // default is "I2S digital source" - ADC type overrides this method
 
  protected:
    /* Post-process audio sample - currently on needed for I2SAdcSource*/
    virtual I2S_datatype postProcessSample(I2S_datatype sample_in) {return(sample_in);}   // default method can be overriden by instances (ADC) that need sample postprocessing

    // Private constructor, to make sure it is not callable except from derived classes
    AudioSource(SRate_t sampleRate, int blockSize) :
      _sampleRate(sampleRate),
      _blockSize(blockSize),
      _initialized(false)
    {};

    SRate_t _sampleRate;            // Microphone sampling rate
    int _blockSize;                 // I2S block size
    bool _initialized;              // Gets set to true if initialization is successful
};

/* Basic I2S microphone source
   All functions are marked virtual, so derived classes can replace them
*/
class I2SSource : public AudioSource {
  public:
    I2SSource(SRate_t sampleRate, int blockSize) :
      AudioSource(sampleRate, blockSize) {
      _config = {
        .mode = i2s_mode_t(I2S_MODE_MASTER | I2S_MODE_RX),
        .sample_rate = _sampleRate,
        .bits_per_sample = I2S_SAMPLE_RESOLUTION,
        .channel_format = I2S_MIC_CHANNEL,
#if ESP_IDF_VERSION >= ESP_IDF_VERSION_VAL(4, 2, 0)
        .communication_format = i2s_comm_format_t(I2S_COMM_FORMAT_STAND_I2S),
        //.intr_alloc_flags = ESP_INTR_FLAG_LEVEL1,
        .intr_alloc_flags = ESP_INTR_FLAG_LEVEL2,
        .dma_buf_count = 8,
        .dma_buf_len = _blockSize,
        .use_apll = 0,
        .bits_per_chan = I2S_data_size,
#else
        .communication_format = i2s_comm_format_t(I2S_COMM_FORMAT_I2S | I2S_COMM_FORMAT_I2S_MSB),
        .intr_alloc_flags = ESP_INTR_FLAG_LEVEL1,
        .dma_buf_count = 8,
        .dma_buf_len = _blockSize,
        .use_apll = false
#endif
      };
    }

    virtual void initialize(int8_t i2swsPin = I2S_PIN_NO_CHANGE, int8_t i2ssdPin = I2S_PIN_NO_CHANGE, int8_t i2sckPin = I2S_PIN_NO_CHANGE, int8_t mclkPin = I2S_PIN_NO_CHANGE, int8_t = I2S_PIN_NO_CHANGE, int8_t = I2S_PIN_NO_CHANGE) {
      if (i2swsPin != I2S_PIN_NO_CHANGE && i2ssdPin != I2S_PIN_NO_CHANGE) {
        if (!pinManager.allocatePin(i2swsPin, true, PinOwner::UM_Audioreactive) ||
            !pinManager.allocatePin(i2ssdPin, false, PinOwner::UM_Audioreactive)) { // #206
          DEBUGSR_PRINTF("\nAR: Failed to allocate I2S pins: ws=%d, sd=%d\n",  i2swsPin, i2ssdPin); 
          return;
        }
      }

      // i2ssckPin needs special treatment, since it might be unused on PDM mics
      if (i2sckPin != I2S_PIN_NO_CHANGE) {
        if (!pinManager.allocatePin(i2sckPin, true, PinOwner::UM_Audioreactive)) {
          DEBUGSR_PRINTF("\nAR: Failed to allocate I2S pins: sck=%d\n",  i2sckPin); 
          return;
        }
      } else {
        #if !defined(CONFIG_IDF_TARGET_ESP32S2) && !defined(CONFIG_IDF_TARGET_ESP32C3)
        // This is an I2S PDM microphone, these microphones only use a clock and
        // data line, to make it simpler to debug, use the WS pin as CLK and SD
        // pin as DATA
        _config.mode = i2s_mode_t(I2S_MODE_MASTER | I2S_MODE_RX | I2S_MODE_PDM); // Change mode to pdm if clock pin not provided. PDM is not supported on ESP32-S2. PDM RX not supported on ESP32-C3
        #endif
      }

      // Reserve the master clock pin if provided
      _mclkPin = mclkPin;
      if (mclkPin != I2S_PIN_NO_CHANGE) {
        if(!pinManager.allocatePin(mclkPin, true, PinOwner::UM_Audioreactive)) return;
        _routeMclk(mclkPin);
      }

      _pinConfig = {
#if ESP_IDF_VERSION >= ESP_IDF_VERSION_VAL(4, 4, 0)
        .mck_io_num = mclkPin,            // "classic" ESP32 supports setting MCK on GPIO0/GPIO1/GPIO3 only. i2s_set_pin() will fail if wrong mck_io_num is provided.
#endif
        .bck_io_num = i2sckPin,
        .ws_io_num = i2swsPin,
        .data_out_num = I2S_PIN_NO_CHANGE,
        .data_in_num = i2ssdPin
      };

      esp_err_t err = i2s_driver_install(I2S_NUM_0, &_config, 0, nullptr);
      if (err != ESP_OK) {
        DEBUGSR_PRINTF("Failed to install i2s driver: %d\n", err);
        return;
      }

      err = i2s_set_pin(I2S_NUM_0, &_pinConfig);
      if (err != ESP_OK) {
        DEBUGSR_PRINTF("Failed to set i2s pin config: %d\n", err);
        i2s_driver_uninstall(I2S_NUM_0);  // uninstall already-installed driver
        return;
      }

#if ESP_IDF_VERSION >= ESP_IDF_VERSION_VAL(4, 2, 0)
      err = i2s_set_clk(I2S_NUM_0, _sampleRate, I2S_SAMPLE_RESOLUTION, I2S_CHANNEL_MONO);  // set bit clocks. Also takes care of MCLK routing if needed.
      if (err != ESP_OK) {
        DEBUGSR_PRINTF("Failed to configure i2s clocks: %d\n", err);
        i2s_driver_uninstall(I2S_NUM_0);  // uninstall already-installed driver
        return;
      }
#endif
      _initialized = true;
    }

    virtual void deinitialize() {
      _initialized = false;
      esp_err_t err = i2s_driver_uninstall(I2S_NUM_0);
      if (err != ESP_OK) {
        DEBUGSR_PRINTF("Failed to uninstall i2s driver: %d\n", err);
        return;
      }
      if (_pinConfig.ws_io_num   != I2S_PIN_NO_CHANGE) pinManager.deallocatePin(_pinConfig.ws_io_num,   PinOwner::UM_Audioreactive);
      if (_pinConfig.data_in_num != I2S_PIN_NO_CHANGE) pinManager.deallocatePin(_pinConfig.data_in_num, PinOwner::UM_Audioreactive);
      if (_pinConfig.bck_io_num  != I2S_PIN_NO_CHANGE) pinManager.deallocatePin(_pinConfig.bck_io_num,  PinOwner::UM_Audioreactive);
      // Release the master clock pin
      if (_mclkPin != I2S_PIN_NO_CHANGE) pinManager.deallocatePin(_mclkPin, PinOwner::UM_Audioreactive);
    }

    virtual void getSamples(float *buffer, uint16_t num_samples) {
      if (_initialized) {
        esp_err_t err;
        size_t bytes_read = 0;        /* Counter variable to check if we actually got enough data */
        I2S_datatype newSamples[num_samples]; /* Intermediary sample storage */

        err = i2s_read(I2S_NUM_0, (void *)newSamples, sizeof(newSamples), &bytes_read, portMAX_DELAY);
        if (err != ESP_OK) {
          DEBUGSR_PRINTF("Failed to get samples: %d\n", err);
          return;
        }

        // For correct operation, we need to read exactly sizeof(samples) bytes from i2s
        if (bytes_read != sizeof(newSamples)) {
          DEBUGSR_PRINTF("Failed to get enough samples: wanted: %d read: %d\n", sizeof(newSamples), bytes_read);
          return;
        }

        // Store samples in sample buffer and update DC offset
        for (int i = 0; i < num_samples; i++) {

          newSamples[i] = postProcessSample(newSamples[i]);  // perform postprocessing (needed for ADC samples)
          
          float currSample = 0.0f;
#ifdef I2S_SAMPLE_DOWNSCALE_TO_16BIT
              currSample = (float) newSamples[i] / 65536.0f;      // 32bit input -> 16bit; keeping lower 16bits as decimal places
#else
              currSample = (float) newSamples[i];                 // 16bit input -> use as-is
#endif
          buffer[i] = currSample;
        }
      }
    }

  protected:
    void _routeMclk(int8_t mclkPin) {
#if !defined(CONFIG_IDF_TARGET_ESP32S2) && !defined(CONFIG_IDF_TARGET_ESP32C3) && !defined(CONFIG_IDF_TARGET_ESP32S3)
  // MCLK routing by writing registers is not needed any more with IDF > 4.4.0
  #if ESP_IDF_VERSION < ESP_IDF_VERSION_VAL(4, 4, 0)
    // this way of MCLK routing only works on "classic" ESP32
      /* Enable the mclk routing depending on the selected mclk pin (ESP32: only 0,1,3)
          Only I2S_NUM_0 is supported
      */
      if (mclkPin == GPIO_NUM_0) {
        PIN_FUNC_SELECT(PERIPHS_IO_MUX_GPIO0_U, FUNC_GPIO0_CLK_OUT1);
        WRITE_PERI_REG(PIN_CTRL,0xFFF0);
      } else if (mclkPin == GPIO_NUM_1) {
        PIN_FUNC_SELECT(PERIPHS_IO_MUX_U0TXD_U, FUNC_U0TXD_CLK_OUT3);
        WRITE_PERI_REG(PIN_CTRL, 0xF0F0);
      } else {
        PIN_FUNC_SELECT(PERIPHS_IO_MUX_U0RXD_U, FUNC_U0RXD_CLK_OUT2);
        WRITE_PERI_REG(PIN_CTRL, 0xFF00);
      }
  #endif
#endif
    }

    i2s_config_t _config;
    i2s_pin_config_t _pinConfig;
    int8_t _mclkPin;
};

/* ES7243 Microphone
   This is an I2S microphone that requires ininitialization over
   I2C before I2S data can be received
*/
class ES7243 : public I2SSource {
  private:
    // I2C initialization functions for ES7243
    void _es7243I2cBegin() {
      Wire.begin(pin_ES7243_SDA, pin_ES7243_SCL, 100000U);
    }

    void _es7243I2cWrite(uint8_t reg, uint8_t val) {
#ifndef ES7243_ADDR
      Wire.beginTransmission(0x13);
#else
      Wire.beginTransmission(ES7243_ADDR);
#endif
      Wire.write((uint8_t)reg);
      Wire.write((uint8_t)val);
      Wire.endTransmission();
    }

    void _es7243InitAdc() {
      _es7243I2cBegin();
      _es7243I2cWrite(0x00, 0x01);
      _es7243I2cWrite(0x06, 0x00);
      _es7243I2cWrite(0x05, 0x1B);
      _es7243I2cWrite(0x01, 0x00); // 0x00 for 24 bit to match INMP441 - not sure if this needs adjustment to get 16bit samples from I2S
      _es7243I2cWrite(0x08, 0x43);
      _es7243I2cWrite(0x05, 0x13);
    }

public:
    ES7243(SRate_t sampleRate, int blockSize) :
      I2SSource(sampleRate, blockSize) {
      _config.channel_format = I2S_CHANNEL_FMT_ONLY_RIGHT;
    };

    void initialize(int8_t sdaPin, int8_t sclPin, int8_t i2swsPin, int8_t i2ssdPin, int8_t i2sckPin, int8_t mclkPin) {
      // Reserve SDA and SCL pins of the I2C interface
      if (!pinManager.allocatePin(sdaPin, true, PinOwner::HW_I2C) ||
          !pinManager.allocatePin(sclPin, true, PinOwner::HW_I2C)) {
        return;
      }

      pin_ES7243_SDA = sdaPin;
      pin_ES7243_SCL = sclPin;

      // First route mclk, then configure ADC over I2C, then configure I2S
      _es7243InitAdc();
      I2SSource::initialize(i2swsPin, i2ssdPin, i2sckPin, mclkPin);
    }

    void deinitialize() {
      // Release SDA and SCL pins of the I2C interface
      pinManager.deallocatePin(pin_ES7243_SDA, PinOwner::HW_I2C);
      pinManager.deallocatePin(pin_ES7243_SCL, PinOwner::HW_I2C);
      I2SSource::deinitialize();
    }

  private:
    int8_t pin_ES7243_SDA;
    int8_t pin_ES7243_SCL;
};

#if !defined(CONFIG_IDF_TARGET_ESP32S2) && !defined(CONFIG_IDF_TARGET_ESP32C3) && !defined(CONFIG_IDF_TARGET_ESP32S3)
// ADC over I2S is only availeable in "classic" ESP32

/* ADC over I2S Microphone
   This microphone is an ADC pin sampled via the I2S interval
   This allows to use the I2S API to obtain ADC samples with high sample rates
   without the need of manual timing of the samples
*/
class I2SAdcSource : public I2SSource {
  public:
    I2SAdcSource(SRate_t sampleRate, int blockSize) :
      I2SSource(sampleRate, blockSize) {
      _config = {
        .mode = i2s_mode_t(I2S_MODE_MASTER | I2S_MODE_RX | I2S_MODE_ADC_BUILT_IN),
        .sample_rate = _sampleRate,
        .bits_per_sample = I2S_SAMPLE_RESOLUTION,
        .channel_format = I2S_CHANNEL_FMT_ONLY_LEFT,
#if ESP_IDF_VERSION >= ESP_IDF_VERSION_VAL(4, 2, 0)
        .communication_format = i2s_comm_format_t(I2S_COMM_FORMAT_STAND_I2S),
#else
        .communication_format = i2s_comm_format_t(I2S_COMM_FORMAT_I2S | I2S_COMM_FORMAT_I2S_MSB),
#endif
        .intr_alloc_flags = ESP_INTR_FLAG_LEVEL1,
        .dma_buf_count = 8,
        .dma_buf_len = _blockSize,
        .use_apll = false,
        .tx_desc_auto_clear = false,
        .fixed_mclk = 0        
      };
    }

    /* identify Audiosource type - I2S-ADC*/
    AudioSourceType getType(void) {return(Type_I2SAdc);}

    void initialize(int8_t audioPin, int8_t = I2S_PIN_NO_CHANGE, int8_t = I2S_PIN_NO_CHANGE, int8_t = I2S_PIN_NO_CHANGE, int8_t = I2S_PIN_NO_CHANGE, int8_t = I2S_PIN_NO_CHANGE) {
      _myADCchannel = 0x0F;
      if(!pinManager.allocatePin(audioPin, false, PinOwner::UM_Audioreactive)) {
         DEBUGSR_PRINTF("failed to allocate GPIO for audio analog input: %d\n", audioPin);
        return;
      }
      _audioPin = audioPin;

      // Determine Analog channel. Only Channels on ADC1 are supported
      int8_t channel = digitalPinToAnalogChannel(_audioPin);
      if (channel > 9) {
        DEBUGSR_PRINTF("Incompatible GPIO used for audio in: %d\n", _audioPin);
        return;
      } else {
        adc_gpio_init(ADC_UNIT_1, adc_channel_t(channel));
        _myADCchannel = channel;
      }

      // Install Driver
      esp_err_t err = i2s_driver_install(I2S_NUM_0, &_config, 0, nullptr);
      if (err != ESP_OK) {
        DEBUGSR_PRINTF("Failed to install i2s driver: %d\n", err);
        return;
      }

      adc1_config_width(ADC_WIDTH_BIT_12);   // ensure that ADC runs with 12bit resolution

      // Enable I2S mode of ADC
      err = i2s_set_adc_mode(ADC_UNIT_1, adc1_channel_t(channel));
      if (err != ESP_OK) {
        DEBUGSR_PRINTF("Failed to set i2s adc mode: %d\n", err);
        return;
      }

      // see example in https://github.com/espressif/arduino-esp32/blob/master/libraries/ESP32/examples/I2S/HiFreq_ADC/HiFreq_ADC.ino
      adc1_config_channel_atten(adc1_channel_t(channel), ADC_ATTEN_DB_11);   // configure ADC input amplification

      #if defined(I2S_GRAB_ADC1_COMPLETELY)
      // according to docs from espressif, the ADC needs to be started explicitly
      // fingers crossed
        err = i2s_adc_enable(I2S_NUM_0);
        if (err != ESP_OK) {
            DEBUGSR_PRINTF("Failed to enable i2s adc: %d\n", err);
            //return;
        }
      #else
        err = i2s_adc_disable(I2S_NUM_0);
		    //err = i2s_stop(I2S_NUM_0);
        if (err != ESP_OK) {
            DEBUGSR_PRINTF("Failed to initially disable i2s adc: %d\n", err);
        }
      #endif

      _initialized = true;
    }


    I2S_datatype postProcessSample(I2S_datatype sample_in) {
      static I2S_datatype lastADCsample = 0;          // last good sample
      static unsigned int broken_samples_counter = 0; // number of consecutive broken (and fixed) ADC samples
      I2S_datatype sample_out = 0;

      // bring sample down down to 16bit unsigned
      I2S_unsigned_datatype rawData = * reinterpret_cast<I2S_unsigned_datatype *> (&sample_in); // C++ acrobatics to get sample as "unsigned"
      #ifndef I2S_USE_16BIT_SAMPLES
        rawData = (rawData >> 16) & 0xFFFF;                       // scale input down from 32bit -> 16bit
        I2S_datatype lastGoodSample = lastADCsample / 16384 ;     // prepare "last good sample" accordingly (26bit-> 12bit with correct sign handling)
      #else
        rawData = rawData & 0xFFFF;                               // input is already in 16bit, just mask off possible junk
        I2S_datatype lastGoodSample = lastADCsample * 4;          // prepare "last good sample" accordingly (10bit-> 12bit)
      #endif

      // decode ADC sample data fields
      uint16_t the_channel = (rawData >> 12) & 0x000F;           // upper 4 bit = ADC channel
      uint16_t the_sample  =  rawData & 0x0FFF;                  // lower 12bit -> ADC sample (unsigned)
      I2S_datatype finalSample = (int(the_sample) - 2048);       // convert unsigned sample to signed (centered at 0);

      if ((the_channel != _myADCchannel) && (_myADCchannel != 0x0F)) { // 0x0F means "don't know what my channel is" 
        // fix bad sample
        finalSample = lastGoodSample;                             // replace with last good ADC sample
        broken_samples_counter ++;
        if (broken_samples_counter > 256) _myADCchannel = 0x0F;   // too  many bad samples in a row -> disable sample corrections
        //Serial.print("\n!ADC rogue sample 0x"); Serial.print(rawData, HEX); Serial.print("\tchannel:");Serial.println(the_channel);
      } else broken_samples_counter = 0;                          // good sample - reset counter

      // back to original resolution
      #ifndef I2S_USE_16BIT_SAMPLES
        finalSample = finalSample << 16;                          // scale up from 16bit -> 32bit;
      #endif

      finalSample = finalSample / 4;                              // mimic old analog driver behaviour (12bit -> 10bit)
      sample_out = (3 * finalSample + lastADCsample) / 4;         // apply low-pass filter (2-tap FIR)
      //sample_out = (finalSample + lastADCsample) / 2;             // apply stronger low-pass filter (2-tap FIR)

      lastADCsample = sample_out;                                 // update ADC last sample
      return(sample_out);
    }


    void getSamples(float *buffer, uint16_t num_samples) {
      /* Enable ADC. This has to be enabled and disabled directly before and
       * after sampling, otherwise Wifi dies
       */
      if (_initialized) {
        #if !defined(I2S_GRAB_ADC1_COMPLETELY)
          // old code - works for me without enable/disable, at least on ESP32.
          //esp_err_t err = i2s_start(I2S_NUM_0);
          esp_err_t err = i2s_adc_enable(I2S_NUM_0);
          if (err != ESP_OK) {
            DEBUGSR_PRINTF("Failed to enable i2s adc: %d\n", err);
            return;
          }
        #endif

        I2SSource::getSamples(buffer, num_samples);

        #if !defined(I2S_GRAB_ADC1_COMPLETELY)
          // old code - works for me without enable/disable, at least on ESP32.
          err = i2s_adc_disable(I2S_NUM_0);  //i2s_adc_disable() may cause crash with IDF 4.4 (https://github.com/espressif/arduino-esp32/issues/6832)
          //err = i2s_stop(I2S_NUM_0);
          if (err != ESP_OK) {
            DEBUGSR_PRINTF("Failed to disable i2s adc: %d\n", err);
            return;
          }
        #endif
      }
    }

    void deinitialize() {
      pinManager.deallocatePin(_audioPin, PinOwner::UM_Audioreactive);
      _initialized = false;
      _myADCchannel = 0x0F;
      
      esp_err_t err;
      #if defined(I2S_GRAB_ADC1_COMPLETELY)
        // according to docs from espressif, the ADC needs to be stopped explicitly
        // fingers crossed
        err = i2s_adc_disable(I2S_NUM_0);
        if (err != ESP_OK) {
          DEBUGSR_PRINTF("Failed to disable i2s adc: %d\n", err);
        }
      #endif

      i2s_stop(I2S_NUM_0);
      err = i2s_driver_uninstall(I2S_NUM_0);
      if (err != ESP_OK) {
        DEBUGSR_PRINTF("Failed to uninstall i2s driver: %d\n", err);
        return;
      }
    }

  private:
    int8_t _audioPin;
    int8_t _myADCchannel = 0x0F;       // current ADC channel for analog input. 0x0F means "undefined"
};
#endif

/* SPH0645 Microphone
   This is an I2S microphone with some timing quirks that need
   special consideration.
*/

// https://github.com/espressif/esp-idf/issues/7192  SPH0645 i2s microphone issue when migrate from legacy esp-idf version (IDFGH-5453)
// a user recommended this: Try to set .communication_format to I2S_COMM_FORMAT_STAND_I2S and call i2s_set_clk() after i2s_set_pin().
class SPH0654 : public I2SSource {
  public:
    SPH0654(SRate_t sampleRate, int blockSize) :
      I2SSource(sampleRate, blockSize)
    {}

    void initialize(uint8_t i2swsPin, uint8_t i2ssdPin, uint8_t i2sckPin, int8_t = I2S_PIN_NO_CHANGE, int8_t = I2S_PIN_NO_CHANGE, int8_t = I2S_PIN_NO_CHANGE) {
      I2SSource::initialize(i2swsPin, i2ssdPin, i2sckPin);
#if !defined(CONFIG_IDF_TARGET_ESP32S2) && !defined(CONFIG_IDF_TARGET_ESP32C3) && !defined(CONFIG_IDF_TARGET_ESP32S3)
// these registers are only existing in "classic" ESP32
      REG_SET_BIT(I2S_TIMING_REG(I2S_NUM_0), BIT(9));
      REG_SET_BIT(I2S_CONF_REG(I2S_NUM_0), I2S_RX_MSB_SHIFT);
#else
      #warning FIX ME! Please.
#endif
    }
};