text: #include <stdio.h>
  #include <string.h>
  #include "freertos/FreeRTOS.h"
  #include "freertos/task.h"
  #include "esp_spi_flash.h"
  #include "esp_err.h"
  #include "esp_log.h"
  #include "esp_partition.h"
  #include "driver/i2s.h"
  #include "driver/adc.h"
  #include "audio_example_file.h"
  #include "esp_adc_cal.h"
  
  static const char* TAG = "ad/da";
  #define V_REF   1100
  #define ADC1_TEST_CHANNEL (ADC1_CHANNEL_7)
  
  #define PARTITION_NAME   "storage"
  
  /*---------------------------------------------------------------
                              EXAMPLE CONFIG
  ---------------------------------------------------------------*/
  //enable record sound and save in flash
  #define RECORD_IN_FLASH_EN        (1)
  //enable replay recorded sound in flash
  #define REPLAY_FROM_FLASH_EN      (1)
  
  //i2s number
  #define EXAMPLE_I2S_NUM           (0)
  //i2s sample rate
  #define EXAMPLE_I2S_SAMPLE_RATE   (16000)
  //i2s data bits
  #define EXAMPLE_I2S_SAMPLE_BITS   (16)
  //enable display buffer for debug
  #define EXAMPLE_I2S_BUF_DEBUG     (0)
  //I2S read buffer length
  #define EXAMPLE_I2S_READ_LEN      (16 * 1024)
  //I2S data format
  #define EXAMPLE_I2S_FORMAT        (I2S_CHANNEL_FMT_RIGHT_LEFT)
  //I2S channel number
  #define EXAMPLE_I2S_CHANNEL_NUM   ((EXAMPLE_I2S_FORMAT < I2S_CHANNEL_FMT_ONLY_RIGHT) ? (2) : (1))
  //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 seconds' data
  #define FLASH_RECORD_SIZE         (EXAMPLE_I2S_CHANNEL_NUM * EXAMPLE_I2S_SAMPLE_RATE * EXAMPLE_I2S_SAMPLE_BITS / 8 * 5)
  #define FLASH_ERASE_SIZE          (FLASH_RECORD_SIZE % FLASH_SECTOR_SIZE == 0) ? FLASH_RECORD_SIZE : FLASH_RECORD_SIZE + (FLASH_SECTOR_SIZE - FLASH_RECORD_SIZE % FLASH_SECTOR_SIZE)
  //sector size of flash
  #define FLASH_SECTOR_SIZE         (0x1000)
  //flash read / write address
  #define FLASH_ADDR                (0x200000)
  
  
  /**
   * @brief I2S ADC/DAC mode init.
   */
  void example_i2s_init()
  {
  	 int i2s_num = EXAMPLE_I2S_NUM;
  	 i2s_config_t i2s_config = {
          .mode = I2S_MODE_MASTER | I2S_MODE_RX | I2S_MODE_TX | I2S_MODE_DAC_BUILT_IN | I2S_MODE_ADC_BUILT_IN,
          .sample_rate =  EXAMPLE_I2S_SAMPLE_RATE,
          .bits_per_sample = EXAMPLE_I2S_SAMPLE_BITS,
  	    .communication_format = I2S_COMM_FORMAT_I2S_MSB,
  	    .channel_format = EXAMPLE_I2S_FORMAT,
  	    .intr_alloc_flags = 0,
  	    .dma_buf_count = 2,
  	    .dma_buf_len = 1024
  	 };
  	 //install and start i2s driver
  	 i2s_driver_install(i2s_num, &i2s_config, 0, NULL);
  	 //init DAC pad
  	 i2s_set_dac_mode(I2S_DAC_CHANNEL_BOTH_EN);
  	 //init ADC pad
  	 i2s_set_adc_mode(I2S_ADC_UNIT, I2S_ADC_CHANNEL);
  }
  
  /*
   * @brief erase flash for recording
   */
  void example_erase_flash()
  {
  #if RECORD_IN_FLASH_EN
      printf("Erasing flash \n");
      const esp_partition_t *data_partition = NULL;
      data_partition = esp_partition_find_first(ESP_PARTITION_TYPE_DATA,
              ESP_PARTITION_SUBTYPE_DATA_FAT, PARTITION_NAME);
      if (data_partition != NULL) {
          printf("partiton addr: 0x%08x; size: %d; label: %s\n", data_partition->address, data_partition->size, data_partition->label);
      }
      printf("Erase size: %d Bytes\n", FLASH_ERASE_SIZE);
      ESP_ERROR_CHECK(esp_partition_erase_range(data_partition, 0, FLASH_ERASE_SIZE));
  #else
      printf("Skip flash erasing...\n");
  #endif
  }
  
  /**
   * @brief debug buffer data
   */
  void example_disp_buf(uint8_t* buf, int length)
  {
  #if EXAMPLE_I2S_BUF_DEBUG
      printf("======\n");
      for (int i = 0; i < length; i++) {
          printf("%02x ", buf[i]);
          if ((i + 1) % 8 == 0) {
              printf("\n");
          }
      }
      printf("======\n");
  #endif
  }
  
  /**
   * @brief Reset i2s clock and mode
   */
  void example_reset_play_mode()
  {
      i2s_set_clk(EXAMPLE_I2S_NUM, EXAMPLE_I2S_SAMPLE_RATE, EXAMPLE_I2S_SAMPLE_BITS, EXAMPLE_I2S_CHANNEL_NUM);
  }
  
  /**
   * @brief Set i2s clock for example audio file
   */
  void example_set_file_play_mode()
  {
      i2s_set_clk(EXAMPLE_I2S_NUM, 16000, EXAMPLE_I2S_SAMPLE_BITS, 1);
  }
  
  /**
   * @brief Scale data to 16bit/32bit for I2S DMA output.
   *        DAC can only output 8bit data value.
   *        I2S DMA will still send 16 bit or 32bit data, the highest 8bit contains DAC data.
   */
  int example_i2s_dac_data_scale(uint8_t* d_buff, uint8_t* s_buff, uint32_t len)
  {
      uint32_t j = 0;
  #if (EXAMPLE_I2S_SAMPLE_BITS == 16)
      for (int i = 0; i < len; i++) {
          d_buff[j++] = 0;
          d_buff[j++] = s_buff[i];
      }
      return (len * 2);
  #else
      for (int i = 0; i < len; i++) {
          d_buff[j++] = 0;
          d_buff[j++] = 0;
          d_buff[j++] = 0;
          d_buff[j++] = s_buff[i];
      }
      return (len * 4);
  #endif
  }
  
  /**
   * @brief Scale data to 8bit for data from ADC.
   *        Data from ADC are 12bit width by default.
   *        DAC can only output 8 bit data.
   *        Scale each 12bit ADC data to 8bit DAC data.
   */
  void example_i2s_adc_data_scale(uint8_t * d_buff, uint8_t* s_buff, uint32_t len)
  {
      uint32_t j = 0;
      uint32_t dac_value = 0;
  #if (EXAMPLE_I2S_SAMPLE_BITS == 16)
      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 / 4096;
      }
  #else
      for (int i = 0; i < len; i += 4) {
          dac_value = ((((uint16_t)(s_buff[i + 3] & 0xf) << 8) | ((s_buff[i + 2]))));
          d_buff[j++] = 0;
          d_buff[j++] = 0;
          d_buff[j++] = 0;
          d_buff[j++] = dac_value * 256 / 4096;
      }
  #endif
  }
  
  /**
   * @brief I2S ADC/DAC example
   *        1. Erase flash
   *        2. Record audio from ADC and save in flash
   *        3. Read flash and replay the sound via DAC
   *        4. Play an example audio file(file format: 8bit/8khz/single channel)
   *        5. Loop back to step 3
   */
  void example_i2s_adc_dac(void*arg)
  {
      const esp_partition_t *data_partition = NULL;
      data_partition = esp_partition_find_first(ESP_PARTITION_TYPE_DATA,
              ESP_PARTITION_SUBTYPE_DATA_FAT, PARTITION_NAME);
      if (data_partition != NULL) {
          printf("partiton addr: 0x%08x; size: %d; label: %s\n", data_partition->address, data_partition->size, data_partition->label);
      } else {
          ESP_LOGE(TAG, "Partition error: can't find partition name: %s\n", PARTITION_NAME);
          vTaskDelete(NULL);
      }
      //1. Erase flash
      example_erase_flash();
      int i2s_read_len = EXAMPLE_I2S_READ_LEN;
      int flash_wr_size = 0;
  
      //2. Record audio from ADC and save in flash
  #if RECORD_IN_FLASH_EN
      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_adc_enable(EXAMPLE_I2S_NUM);
      while (flash_wr_size < FLASH_RECORD_SIZE) {
          //read data from I2S bus, in this case, from ADC.
          i2s_read_bytes(EXAMPLE_I2S_NUM, (char*) i2s_read_buff, i2s_read_len, portMAX_DELAY);
          example_disp_buf((uint8_t*) i2s_read_buff, 64);
          //save original data from I2S(ADC) into flash.
          esp_partition_write(data_partition, flash_wr_size, i2s_read_buff, i2s_read_len);
          flash_wr_size += i2s_read_len;
          ets_printf("Sound recording %u%%\n", flash_wr_size * 100 / FLASH_RECORD_SIZE);
      }
      i2s_adc_disable(EXAMPLE_I2S_NUM);
      free(i2s_read_buff);
      i2s_read_buff = NULL;
      free(flash_write_buff);
      flash_write_buff = NULL;
  #endif
  
      uint8_t* flash_read_buff = (uint8_t*) calloc(i2s_read_len, sizeof(char));
      uint8_t* i2s_write_buff = (uint8_t*) calloc(i2s_read_len, sizeof(char));
      while (1) {
  
          //3. Read flash and replay the sound via DAC
  #if REPLAY_FROM_FLASH_EN
          for (int rd_offset = 0; rd_offset < flash_wr_size; rd_offset += FLASH_SECTOR_SIZE) {
              //read I2S(ADC) original data from flash
              esp_partition_read(data_partition, rd_offset, flash_read_buff, FLASH_SECTOR_SIZE);
              //process data and scale to 8bit for I2S DAC.
              example_i2s_adc_data_scale(i2s_write_buff, flash_read_buff, FLASH_SECTOR_SIZE);
              //send data
              i2s_write_bytes(EXAMPLE_I2S_NUM, (char*) i2s_write_buff, FLASH_SECTOR_SIZE, portMAX_DELAY);
              printf("playing: %d %%\n", rd_offset * 100 / flash_wr_size);
          }
  #endif
  
          //4. Play an example audio file(file format: 8bit/16khz/single channel)
          printf("Playing file example: \n");
          int offset = 0;
          int tot_size = sizeof(audio_table);
          example_set_file_play_mode();
          while (offset < tot_size) {
              int play_len = ((tot_size - offset) > (4 * 1024)) ? (4 * 1024) : (tot_size - offset);
              int i2s_wr_len = example_i2s_dac_data_scale(i2s_write_buff, (uint8_t*)(audio_table + offset), play_len);
              i2s_write_bytes(EXAMPLE_I2S_NUM, (const char*) i2s_write_buff, i2s_wr_len, portMAX_DELAY);
              offset += play_len;
              example_disp_buf((uint8_t*) i2s_write_buff, 32);
          }
          vTaskDelay(100 / portTICK_PERIOD_MS);
          example_reset_play_mode();
      }
      free(flash_read_buff);
      free(i2s_write_buff);
      vTaskDelete(NULL);
  }
  
  void adc_read_task(void* arg)
  {
      adc1_config_width(ADC_WIDTH_12Bit);
      adc1_config_channel_atten(ADC1_TEST_CHANNEL, ADC_ATTEN_11db);
      esp_adc_cal_characteristics_t characteristics;
      esp_adc_cal_characterize(ADC_UNIT_1, ADC_ATTEN_DB_11, ADC_WIDTH_BIT_12, V_REF, &characteristics);
      while(1) {
          uint32_t voltage;
          esp_adc_cal_get_voltage(ADC1_TEST_CHANNEL, &characteristics, &voltage);
          ESP_LOGI(TAG, "%d mV", voltage);
          vTaskDelay(200 / portTICK_RATE_MS);
      }
  }
  
  esp_err_t app_main()
  {
      example_i2s_init();
      esp_log_level_set("I2S", ESP_LOG_INFO);
      xTaskCreate(example_i2s_adc_dac, "example_i2s_adc_dac", 1024 * 2, NULL, 5, NULL);
      xTaskCreate(adc_read_task, "ADC read task", 2048, NULL, 5, NULL);
      return ESP_OK;
  }
  
  
  