ESP32 Forum

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static void init_i2s()
{
    i2s_config_t i2s_config = {
        .mode = I2S_MODE_MASTER | I2S_MODE_RX,                                  // Receive
        .sample_rate = SAMPLE_RATE,
        .bits_per_sample = BITS_PER_SAMPLE,
        .channel_format = I2S_CHANNEL_FMT_RIGHT_LEFT,
        .communication_format = I2S_COMM_FORMAT_I2S | I2S_COMM_FORMAT_I2S_MSB,
        .dma_buf_count = 14,                                                    // number of buffers, 128 max.
        .dma_buf_len = 32*2,                                                    // size of each buffer
        .intr_alloc_flags = ESP_INTR_FLAG_LEVEL1                                //Interrupt level 1
    };
    i2s_pin_config_t pin_config = {
        .bck_io_num = 26,
        .ws_io_num = 25,
        .data_in_num = 22,
        .data_out_num = I2S_PIN_NO_CHANGE                                       //was -1
    };

    i2s_driver_install(I2S_NUM, &i2s_config, 0, NULL);
    i2s_set_pin(I2S_NUM, &pin_config);
}

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#define SAMPLE_RATE     (48000) 
#define I2S_NUM         (0)
#define BUFFER_SAMPLES  (2048)
#define BITS_PER_SAMPLE (32) 

Code: Select all

SPH0645

                   LEFT                                        RIGHT
 Decimal Value:Binary Value                     | Decimal Value:Binary Value
-------------- --------------------------------   ------------- --------------------------------
Raspberry - 32-bit quiet
             0:00000000000000000000000000000000 |    -112721920:11111001010010000000000000000000 
             0:00000000000000000000000000000000 |    -112689152:11111001010010001000000000000000 
             0:00000000000000000000000000000000 |    -112885760:11111001010001011000000000000000 

ESP32 - 32-bit quiet
             1:00000000000000000000000000000001 |    -223051776:11110010101101001000000000000000 
             1:00000000000000000000000000000001 |    -222855168:11110010101101111000000000000000 
             1:00000000000000000000000000000001 |    -222756864:11110010101110010000000000000000 
             

Code: Select all

#include <stdio.h>
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "esp_system.h"
#include "driver/i2s.h"

#define BITS_PER_SAMPLE     (32)        // 8, 16, 24, 32
#define SAMPLE_RATE         (48000)
#define I2S_NUM             (0)
#define FRAMES_REQUESTED    (32)

#if BITS_PER_SAMPLE==32
  typedef int BUFFER_TYPE;
#elif BITS_PER_SAMPLE==24
  typedef int BUFFER_TYPE;
#elif BITS_PER_SAMPLE==16
  typedef short BUFFER_TYPE;
#elif BITS_PER_SAMPLE==8
  typedef byte BUFFER_TYPE;
#endif


static void init_i2s()
{
    i2s_config_t i2s_config = {
        .mode = I2S_MODE_MASTER | I2S_MODE_RX,                                  // Receive
        .sample_rate = SAMPLE_RATE,
        .bits_per_sample = BITS_PER_SAMPLE,
        .channel_format = I2S_CHANNEL_FMT_RIGHT_LEFT,
        .communication_format = I2S_COMM_FORMAT_I2S | I2S_COMM_FORMAT_I2S_MSB,  
        .dma_buf_count = 32,
        .dma_buf_len = 32*2,
        .intr_alloc_flags = ESP_INTR_FLAG_LEVEL1
    };
   
    i2s_pin_config_t pin_config = {
        .ws_io_num = 23,
        .bck_io_num = 22,
        .data_in_num = 21,
      .data_out_num = I2S_PIN_NO_CHANGE
  };

    i2s_driver_install(I2S_NUM, &i2s_config, 0, NULL);
    i2s_set_pin(I2S_NUM, &pin_config);
}


void printBits(size_t const size, void const * const ptr)
{
    unsigned char *b = (unsigned char*) ptr;
    unsigned char byte;
    int i, j;

    for (i=size-1;i>=0;i--)
    {
        for (j=7;j>=0;j--)
        {
            byte = (b[i] >> j) & 1;
            printf("%u", byte);
        }
    }
    printf(" ");
}

void print_buffer_as_binary(BUFFER_TYPE *p, int len)
{
    int i;
    BUFFER_TYPE frame = 0;

    for (i = 0; i < len; i++) {
        if (i%2 == 0) printf("\n");
        frame = p[i];
        printf("%14d:", frame);
        printBits(sizeof(frame), &frame);
        if (i%2 == 0) printf("|");
    }
    printf("\n");
}

void print_bytes(void *p, size_t len)
{
    size_t i;
    printf("(");
    for (i = 0; i < len; ++i) {
        printf("%d", ((char*)p)[i]);
        if (i + 1 < len)
          printf(" ");
    }
    printf(")");
}

void app_main()
{
    unsigned int i;
    int frames_read = 0, buffer_size_in_bytes = 0;

    TickType_t ticks_to_wait = 1000;

    buffer_size_in_bytes = FRAMES_REQUESTED*sizeof(BUFFER_TYPE);
    char *buffer = (char*)malloc(buffer_size_in_bytes);

    // nvs_flash_init();
    init_i2s();
  
    // Skip initial frames
    for(i = 0; i < 6; i++) {
        frames_read = i2s_read_bytes(I2S_NUM, buffer, FRAMES_REQUESTED, 0) / sizeof(BUFFER_TYPE);
    }

    // Main loop
    for(i = 0; i < 100; i++) {
        frames_read = i2s_read_bytes(I2S_NUM, buffer, FRAMES_REQUESTED, ticks_to_wait) / sizeof(BUFFER_TYPE);

        print_buffer_as_binary(buffer, frames_read);   
    }
    printf("\n\n");
    printf("Done! \n");
}

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Raspberry - 16-bit quiet
             0:0000000000000000 |            -3:1111111111111101 
             0:0000000000000000 |            -2:1111111111111110 
             0:0000000000000000 |             4:0000000000000100 

ESP32 - 16-bit quiet
            16:0000000000010000 |             0:0000000000000000 
            15:0000000000001111 |             0:0000000000000000 
            15:0000000000001111 |            -2:1111111111111110 
            

Code: Select all

Raspberry - 32-bit Loud
             0:00000000000000000000000000000000 |    -966652416:11000110011000100000111000000000 
             0:00000000000000000000000000000000 |    -223758464:11110010101010011011011110000000 
             0:00000000000000000000000000000000 |     454887424:00011011000111010000100000000000 

ESP32 - 32-bit Loud
             0:00000000000000000000000000000000 |     190961663:00001011011000011101011111111111 
            -1:11111111111111111111111111111111 |    -920545793:11001001001000011001010111111111 
            -1:11111111111111111111111111111111 |     381301248:00010110101110100011001000000000 
            

Code: Select all

    -182616001:11110101000111011000000000111111 |            -1:11111111111111111111111111111111
    -182026177:11110101001001101000000000111111 |            -1:11111111111111111111111111111111
    -181436353:11110101001011111000000000111111 |            -1:11111111111111111111111111111111
    -180944833:11110101001101110000000000111111 |            -1:11111111111111111111111111111111

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        239231:00000000000000111010011001111111 |            -1:11111111111111111111111111111111
        671871:00000000000010100100000001111111 |            -1:11111111111111111111111111111111
       1137279:00000000000100010101101001111111 |            -1:11111111111111111111111111111111
       1008255:00000000000011110110001001111111 |            -1:11111111111111111111111111111111