nrfx_i2s library never recognized

[ZackBoi]

I am trying to use the nrfx_i2s library to run neopixels on a nRF52 DK. I am using SES to compile and flash the code. I am having trouble correctly using the library though. For the init, start, stop, and uniniti i2s functions I get errors "undefined reference to `nrfx_i2s_init" for all of them. I have the include header at the top for #include "nrfx_i2s.h" and I make sure that the user include directories settings in SES includes the locations of the .h and .c files. I also "Added Existing Files" for the .c file to make sure I wasn't missing anything. Still get an error though.

I am using SDK 17 on Mac with S132 soft device on nRF52 DK with a nRF52832 chip and PCA10040.

[Egor]

Hey Zack

I'm also working on neopixel solution with i2s for nRF52840 chip and SDK 17 on Win.

Having the same issue: "...integration/nrfx/legacy/nrf_drv_i2s.h:103: undefined reference to `nrfx_i2s_init'".

Please leave the comment when you find the solution of this.

BTW: Have you set the I2S_ENABLED to 1 in sdk_config.h ?

PS: probably we could try an example from Didrik (last post from him): https://devzone.nordicsemi.com/f/nordic-q-a/63708/i2s-loopback-example-missing-in-installation-folder/260841

[ZackBoi]

Hi Egor,

I figured it out. It was the I2S_ENABLED property in the sdk_config file like you mentioned. After switching it to 1 it started working.

The reference code I am working with is here: https://github.com/rmptxf/NeoController, in the ble_app_neocontroller folder. In this code there is a custom ble service and characteristic that controls the colors of the neopixels. If you just want to quickly test if the neopixel-code is working, start messing around with the for(;;) loop in main() and utilize the set_neopixel_data() function.

[ZackBoi]

Here is the code without all of the ble stuff:

#include "nrf_delay.h"
#include "nrf_drv_i2s.h"

#define neopixels_number                8                                       /**< Neopixels number. */
#define neopixel_pin                    16                                      /**< Neopixel pin number. */

#define reset_bits                      6                                       /**< Reset bits. */
#define i2s_buffer_size                 ((3 * neopixels_number) + reset_bits)   /**< i2d buffer size for driving the neopixel. */
static uint32_t m_buffer_tx[i2s_buffer_size];
static uint32_t       * volatile mp_block_to_fill  = NULL;

static void set_neopixel_data(uint8_t led_index, uint8_t r, uint8_t g, uint8_t b);

/**@brief Function for handeling the i2s data.
 *
 */
static void i2s_data_handler(nrf_drv_i2s_buffers_t const * p_released,
                             uint32_t                      status)
{
    ret_code_t err_code;
    ASSERT(p_released);

    if (!(status & NRFX_I2S_STATUS_NEXT_BUFFERS_NEEDED))
    {
        return;
    }

    if (!p_released->p_rx_buffer)
    {
        nrf_drv_i2s_buffers_t const next_buffers = {
            .p_tx_buffer = m_buffer_tx,
        };
        err_code = nrf_drv_i2s_next_buffers_set(&next_buffers);
        APP_ERROR_CHECK(err_code);

        mp_block_to_fill = m_buffer_tx;
    }
    else
    {      
        err_code = nrf_drv_i2s_next_buffers_set(p_released);
        APP_ERROR_CHECK(err_code);
        mp_block_to_fill = (uint32_t *)p_released->p_tx_buffer;
    }
}

/**@brief Function for calculating the rgb channels data value.
 *
 */
static uint32_t rgb_channels_value(uint8_t channel_level)
{
    uint32_t value = 0;

    // 0 
    if(channel_level == 0) {
        value = 0x88888888;
    }
    // 255
    else if (channel_level == 255) {
        value = 0xeeeeeeee;
    }
    else 
    {
        // apply 4-bit 0xe HIGH pattern wherever level bits are 1.
        value = 0x88888888;
        for (uint8_t i = 0; i < 8; i++) 
        {
            if((1 << i) & channel_level) 
            {
                uint32_t mask = ~(0x0f << 4*i);
                uint32_t patt = (0x0e << 4*i);
                value = (value & mask) | patt;
            }
        }

        // swap 16 bits
        value = (value >> 16) | (value << 16);
    }

    return value;
}

/**@brief Function for setting the leds (rgb) data in the i2s buffer.
 *
 *@param led_n   neopixel number in the array starting with 0.
 *@param r       red led level.
 *@param g       green led level.
 *@param b       blue led level.
 */
static void set_neopixel_data(uint8_t led_index, uint8_t r, uint8_t g, uint8_t b)
{
    for(int i = 0; i < (3 * neopixels_number); i += 3) 
    {
        if (i == (3 * led_index)) 
        {          
           m_buffer_tx[i]   = rgb_channels_value(g);
           m_buffer_tx[i+1] = rgb_channels_value(r);
           m_buffer_tx[i+2] = rgb_channels_value(b);
          
        }
        else 
        {
            m_buffer_tx[i]   = 0x88888888;
            m_buffer_tx[i+1] = 0x88888888;
            m_buffer_tx[i+2] = 0x88888888;
        }
    }

    // reset 
    for(int i = (3 * neopixels_number); i < i2s_buffer_size; i++) 
    {
        m_buffer_tx[i] = 0;
    }

     nrf_drv_i2s_buffers_t const initial_buffers = {
            .p_tx_buffer = m_buffer_tx,
        };
}

/**@brief Function for initialising the i2s.
 *
 */
static void i2s_init()
{
    uint32_t err_code = NRF_SUCCESS;

    nrf_drv_i2s_config_t config = NRF_DRV_I2S_DEFAULT_CONFIG;
    config.sdin_pin  = NRFX_I2S_PIN_NOT_USED;
    config.sdout_pin = neopixel_pin;

    config.mck_setup = NRF_I2S_MCK_32MDIV10;
    config.ratio     = NRF_I2S_RATIO_32X;
    config.channels  = NRF_I2S_CHANNELS_STEREO;
    err_code = nrf_drv_i2s_init(&config, i2s_data_handler);
    APP_ERROR_CHECK(err_code);
}

/**@brief Function for application main entry.
 */
int main(void)
{
    ret_code_t err_code;
    bool erase_bonds;

    nrf_drv_i2s_buffers_t const initial_buffers = 
    {
        .p_tx_buffer = m_buffer_tx 
    };

    i2s_init();

    err_code = nrf_drv_i2s_start(&initial_buffers, i2s_buffer_size, 0);            
    APP_ERROR_CHECK(err_code);
    set_neopixel_data(0,100,100,100); // Turn Off the Pixel

    // Enter main loop.
    for (;;)
    {
        set_neopixel_data(0,20,0,0); // Turn Off the Pixel
        nrf_delay_ms(250);
        set_neopixel_data(1,0,20,0); // Turn Off the Pixel
        nrf_delay_ms(1000);
        set_neopixel_data(2,0,0,20); // Turn Off the Pixel
        nrf_delay_ms(1000);
        set_neopixel_data(0,0,0,20); // Turn Off the Pixel
        nrf_delay_ms(1000);
    }
}


/**
 * @}
 */
/**/

[Egor]

Hi Zack. Thanks for sharing your code.

I finally found the issue. It was in SDK location. The full path to SDK was: D:\Projects\BLE\Nordic\nRF5_SDK_17.0.2

When I moved SDK to the root folder like: D:\nRF5_SDK_17.0.2 the issue has gone.