ESP32 Forum

Posted: **Wed May 06, 2020 8:52 pm**

I am trying to get one esp32 to send its audio data to another esp32 via i2s. I am having a lot of trouble though.

The idea behind it is to create a task to read the data from the pins using i2s_num_1 and output the data onto a speaker using i2s_num_0 and an external i2s decoder. I know everything works except for what I provided in the code below.

The problem is that I am not quite sure how much data to receive when using i2s_read()

Here is my main:

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i2s_config_t i2s_config_in = {
        .mode = I2S_MODE_MASTER | I2S_MODE_RX,                                 
        .sample_rate = 44100,
        .bits_per_sample = 16,
        .channel_format = I2S_CHANNEL_FMT_RIGHT_LEFT,                           //2-channels
        .communication_format = I2S_COMM_FORMAT_PCM,
        .dma_buf_count = 6,
        .dma_buf_len = 60,
        .intr_alloc_flags = 0                                                 //Default interrupt priority
    };
    i2s_driver_install(1, &i2s_config_in, 0, NULL);

    i2s_pin_config_t pin_config_in = {
        .bck_io_num = 13,
        .ws_io_num = 15,
        .data_out_num = -1,
        .data_in_num = 21                                                      //Not used
    };

    i2s_set_pin(1, &pin_config_in);

    i2s_config_t i2s_config_out = {
        .mode = I2S_MODE_MASTER | I2S_MODE_TX,                                  // Only TX
        .sample_rate = 44100,
        .bits_per_sample = 16,
        .channel_format = I2S_CHANNEL_FMT_RIGHT_LEFT,                           //2-channels
        .communication_format = I2S_COMM_FORMAT_PCM,
        .dma_buf_count = 6,
        .dma_buf_len = 60,
        .intr_alloc_flags = 0,                                                  //Default interrupt priority
        .tx_desc_auto_clear = true                                              //Auto clear tx descriptor on underflow
    };
    i2s_driver_install(0, &i2s_config_out, 0, NULL);

    i2s_pin_config_t pin_config_out = {
        .bck_io_num = 26,
        .ws_io_num = 22,
        .data_out_num = 25,
        .data_in_num = -1                                                      //Not used
    };

    i2s_set_pin(0, &pin_config_out);


    ESP_LOGI(BT_APP_CORE_TAG, "It set the config");
    i2s_start_up();

And here is the i2s_start_up() code:

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static void bt_i2s_task_handler(void *arg)
{
    uint8_t *data = NULL;
    size_t item_size = 1;  //(I have no idea how to get the item size from the other esp32)
    size_t bytes_written = 0;
    size_t bytes_read = 0;

    for (;;) {
        i2s_read(1, data, item_size, &bytes_read, portMAX_DELAY);
        i2s_write(0, data, bytes_read, &bytes_written, portMAX_DELAY);
    }
}


void i2s_start_up(void) {
    xTaskCreate(bt_i2s_task_handler, "BtI2ST", 2048, NULL, configMAX_PRIORITIES - 3, &s_bt_i2s_task_handle);
    return;
}

When I run the code i get the following error:

Guru Meditation Error: Core 1 panic'ed (StoreProhibited). Exception was unhandled.
Core 1 register dump:
PC : 0x4000c333 PS : 0x00060030 A0 : 0x800d6924 A1 : 0x3ffc1470
A2 : 0x00000000 A3 : 0x3ffbd470 A4 : 0x00000001 A5 : 0x00000000
A6 : 0x00000000 A7 : 0x00000000 A8 : 0x00000000 A9 : 0x3ffc1420
A10 : 0x3ffc0054 A11 : 0x3ffbd258 A12 : 0x3ffbfe50 A13 : 0x00000001
A14 : 0x00000003 A15 : 0x00060023 SAR : 0x00000000 EXCCAUSE: 0x0000001d
EXCVADDR: 0x00000000 LBEG : 0x4000c2e0 LEND : 0x4000c2f6 LCOUNT : 0xffffffff

ELF file SHA256: a72a99211524cdeb932b273ad1e332af135051e67ec5493adb42e2294ca8a515

Backtrace: 0x4000c330:0x3ffc1470 0x400d6921:0x3ffc1480 0x400d4115:0x3ffc14b0 0x40087a3d:0x3ffc14e0
0x400d6921: i2s_read at /Users/gabe/esp/esp-idf/components/driver/i2s.c:1144

0x400d4115: bt_i2s_task_handler at /Users/gabe/development/basspack/a2dp_source/build/../main/bt_app_core.c:126 (discriminator 1)

0x40087a3d: vPortTaskWrapper at /Users/gabe/esp/esp-idf/components/freertos/port.c:143

Rebooting...

I am sure there are probably many problems with this code, but I am uncertain where to even begin. Any help would be great! Thanks!

Posted: **Thu May 07, 2020 10:28 am**

i2s_read does not allocate memory by itself, you need to make `data` a valid pointer to some memory. (Also, on your command wrt item_size: you can't know as I2S is a stream protocol.)

Posted: **Thu May 07, 2020 4:40 pm**

Okay, so I allocated some memory to the data and that seemed to fix many of the bugs! Thank you!

If I cannot know the size of the data, that probably means i2s_read() is not an option for this. Is there another efficient way to transfer the audio data from one esp32 to the other via pins?

Thanks!

Posted: **Fri May 08, 2020 9:24 am**

You could either use e.g. SPI or UART, or invent some kind of packetized format to send over I2S. However, do you actually *need* to know the size of what the other ESP sends? Can't you just keep streaming from I2S to the speaker?

Posted: **Sat May 09, 2020 11:59 pm**

I am just trying to see if I can understand I2s better by sending the data from one esp32 to another.

There is one thing I am confused about. The function

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i2s_read(i2s_port_t i2s_num, void *dest, size_t size, size_t *bytes_read, TickType_t ticks_to_wait)

is confusing. What does the term "size_t size" mean? The documentation says "Size of data in bytes", but what does that mean exactly? Is that the size of the data I am reading through I2s or is it the size of the space that I have allocated for the data?

Thanks!

ESP32 Forum

Can one esp32 send audio data to another esp32 via I2s? Help appreciated

Can one esp32 send audio data to another esp32 via I2s? Help appreciated

Re: Can one esp32 send audio data to another esp32 via I2s? Help appreciated

Re: Can one esp32 send audio data to another esp32 via I2s? Help appreciated

Re: Can one esp32 send audio data to another esp32 via I2s? Help appreciated

Re: Can one esp32 send audio data to another esp32 via I2s? Help appreciated