I'd like to know how to control the Neopixel LED.

RE: I'd like to know how to control the Neopixel LED.

Stian Røed Hafskjold — Mon, 11 Jan 2021 13:46:24 GMT

Hi, you will have to check the output of the I2S pins with a logic analyzer, and see if there are any differences between the outputs.

RE: I'd like to know how to control the Neopixel LED.

schosdas — Mon, 11 Jan 2021 02:21:54 GMT

Hello

I succeeded in output one LED using I2S. However, when more LEDs are used, LEDs except the first one have a strange output. I suspect there might be a problem transferring the buffer.

Can you tell me what the problem is with this code and how to solve it?

// https://rs29.tistory.com/14

#include <stdio.h>
#include "nrf.h"
#include "nrf_drv_i2s.h"
#include "nrf_delay.h"
#include "app_util_platform.h"
#include "app_error.h"
#include "boards.h"

#include "nrf_log.h"
#include "nrf_log_ctrl.h"
#include "nrf_log_default_backends.h"


#define sk6812_led_num 3 //number of LEDs
#define sk6812_rst_buffer 8 //reset, 32bit*8= 256bit = 0.3125us*256 = 80us
#define sk6812_buf_len sk6812_led_num * 4 + 8 //buffer size, 32bit

//[0][0]=Green, [0][1]=Red, [0][2]=Blue, [0][3]=White
static uint32_t sk6812_buffer[2][sk6812_buf_len] = {0}; //sk6812_buffer[2][sk6812_buf_len]

volatile bool i2s_running = false;

//LED color data, apply in buffer
typedef struct sk6812_rgbw{
  uint8_t red;
  uint8_t green;
  uint8_t blue;
  uint8_t white;
}sk6812_rgbw_struct;



// This is the I2S data handler - all data exchange related to the I2S transfers is done here.
//The data handler set with I2S initialization is called immediately after transmission and after transmission completion.
static void i2s_data_handler(nrf_drv_i2s_buffers_t const * p_released, uint32_t status)
{
    static uint8_t transfer_chk = 0;

    if(p_released->p_tx_buffer != 0) //If p_tx_buffer was previously delivered to the buffer
    {
      transfer_chk++;	//when send data count++
    }

    if(transfer_chk != 0) //after data send, stop i2s
    {
      nrf_drv_i2s_stop();
      i2s_running = false;
      transfer_chk = 0;	
    }
}

//data send to buffer though DMA
void sk6812_send_buffer()
{
  uint32_t err_code = NRF_SUCCESS;
  
  nrf_drv_i2s_buffers_t const i2s_buffers = {.p_tx_buffer = sk6812_buffer[0],}; 

  if(i2s_running == false) //if no runnning i2s
  {
    err_code = nrf_drv_i2s_start(&i2s_buffers, sk6812_buf_len, 0); //buffer, size, flag
    
    APP_ERROR_CHECK(err_code);

    i2s_running == true;
  }
}


void sk6812_set_color(sk6812_rgbw_struct* set_color, uint8_t index)
{
  uint32_t temp_g, temp_r, temp_b, temp_w = 0;

  for(uint8_t i=0;i<8;i++)	//Green
  {
    if((set_color->green>>(7-i))&0x1==1)
    {
      temp_g|=0xC<<(7-i)*4;
    }
    else
    {
      temp_g|=0x8<<(7-i)*4;
    }

    if((set_color->red>>(7-i))&0x1==1)	//Red
    {
      temp_r|=0xC<<(7-i)*4;
    }
    else
    {
      temp_r|=0x8<<(7-i)*4;
    }

    if((set_color->blue>>(7-i))&0x1==1)	//Blue
    {
      temp_b|=0xC<<(7-i)*4;
    }
    else
    {
      temp_b|=0x8<<(7-i)*4;
    }

    if((set_color->white>>(7-i))&0x1==1)	//White
    {
      temp_w|=0xC<<(7-i)*4;
    }
    else
    {
      temp_w|=0x8<<(7-i)*4;
    }
  }
  
  sk6812_buffer[0][index*4]=((temp_g&0x0000FFFF)<<16)|((temp_g&0xFFFF0000)>>16);
  sk6812_buffer[0][index*4+1]=((temp_r&0x0000FFFF)<<16)|((temp_r&0xFFFF0000)>>16);
  sk6812_buffer[0][index*4+2]=((temp_b&0x0000FFFF)<<16)|((temp_b&0xFFFF0000)>>16);
  sk6812_buffer[0][index*4+3]=((temp_w&0x0000FFFF)<<16)|((temp_w&0xFFFF0000)>>16);

  sk6812_send_buffer();	
  nrf_delay_ms(1);
}



int main(void)
{
    uint32_t err_code = NRF_SUCCESS;

    err_code = NRF_LOG_INIT(NULL);
    APP_ERROR_CHECK(err_code);

    //NRF_LOG_DEFAULT_BACKENDS_INIT();

    //NRF_LOG_INFO("I2S loopback example started.");

    //I2S setting
    nrf_drv_i2s_config_t config = NRF_DRV_I2S_DEFAULT_CONFIG;	
    config.sdout_pin = I2S_SDOUT_PIN;	//SDOUT PIN 27
    config.mck_setup = NRF_I2S_MCK_32MDIV10;
    config.ratio     = NRF_I2S_RATIO_32X;
    config.sample_width=NRF_I2S_SWIDTH_16BIT;	
    config.channels  = NRF_I2S_CHANNELS_STEREO;
    
    err_code = nrf_drv_i2s_init(&config, i2s_data_handler);	
    APP_ERROR_CHECK(err_code);

    sk6812_rgbw_struct temp_rgbw;

    //color setting
    temp_rgbw.red = 0;
    temp_rgbw.green = 0;
    temp_rgbw.blue = 0;
    temp_rgbw.white = 0;

    for(uint8_t i=0;i<sk6812_led_num;i++) //first time led off
    {
      sk6812_set_color(&temp_rgbw,i);
    }


    for (;;)
    {
        //firt led
        temp_rgbw.red = 128;
        temp_rgbw.green = 0;
        temp_rgbw.blue = 0;
        temp_rgbw.white = 0; 

        sk6812_set_color(&temp_rgbw,0);

        //second led
        temp_rgbw.red = 0;
        temp_rgbw.green = 128;
        temp_rgbw.blue = 0;
        temp_rgbw.white = 0; 

        sk6812_set_color(&temp_rgbw,1); 
        
        //third led
        temp_rgbw.red = 0;
        temp_rgbw.green = 0;
        temp_rgbw.blue = 128;
        temp_rgbw.white = 0; 

        sk6812_set_color(&temp_rgbw,2);         
    }
}

/** @} */

Thank you.

RE: I'd like to know how to control the Neopixel LED.

Stian Røed Hafskjold — Wed, 30 Dec 2020 10:57:13 GMT

Description of the error code:

NRFX_ERROR_INVALID_ADDR

If the provided buffers are not placed in the Data RAM region.

https://infocenter.nordicsemi.com/topic/com.nordic.infocenter.sdk5.v15.2.0/group__nrfx__i2s.html?cp=7_5_2_6_9_0_7_1_9#ga2c12cf4e0542b5f62303526c0ab410e5

How are you declaring the buffers? Try to declare the buffers as static

RE: I'd like to know how to control the Neopixel LED.

schosdas — Thu, 24 Dec 2020 06:48:26 GMT

Hello, Stian.

I started with the I2S example of SDK v17.0.
'nrf_drv_i2s_start()' was missing from the code I uploaded, so I added it to main() and ran it again.

However, an error is output from nrf_drv_i2s_start. This example seems to have been made from the old version of SDK. Is there a problem with transplanting the old version of the SDK?

int main(void)
{
    uint32_t err_code = NRF_SUCCESS;

    err_code = NRF_LOG_INIT(NULL);
    APP_ERROR_CHECK(err_code);

    NRF_LOG_DEFAULT_BACKENDS_INIT();

    NRF_LOG_INFO("I2S loopback example started.");

    set_led_data(); //first time
    //I2S setting
    nrf_drv_i2s_config_t config = NRF_DRV_I2S_DEFAULT_CONFIG;
    // In Master mode the MCK frequency and the MCK/LRCK ratio should be
    // set properly in order to achieve desired audio sample rate (which
    // is equivalent to the LRCK frequency).
    // For the following settings we'll get the LRCK frequency equal to
    // 15873 Hz (the closest one to 16 kHz that is possible to achieve).
    config.sdin_pin  = I2S_SDIN_PIN; //26
    config.sdout_pin = I2S_SDOUT_PIN; //27
    config.mck_setup = NRF_I2S_MCK_32MDIV10; //< 32 MHz / 10 = 3.2 MHz.
    config.ratio     = NRF_I2S_RATIO_32X; //96X, //< LRCK = MCK / 32.
    config.channels  = NRF_I2S_CHANNELS_STEREO;

    err_code = nrf_drv_i2s_init(&config, data_handler);
    APP_ERROR_CHECK(err_code);

    // start I2S
    g_i2s_running = true;
    g_i2s_start = true;

    g_demo_mode = 2; //0~2

    err_code = nrf_drv_i2s_start(m_buffer_tx, I2S_BUFFER_SIZE, 0);
    APP_ERROR_CHECK(err_code);

    for (;;)
    {
        // stop I2S
        //nrf_drv_i2s_stop();

        nrf_delay_ms(250);

        // update 
        if (g_i2s_running) 
        {
            nled = (nled + 1) % NLEDS;                
            set_led_data();
        }
    }
}

<error> app: ERROR 16 [NRF_ERROR_INVALID_ADDR] at Y:\YSC\Project\CODE\Nordic\SDK17.0\nRF5_SDK_17.0.0_9d13099\examples\peripheral\i2s\main.c:162

PC at: 0x00002441

<error> app: End of error report

Thank you for your help.

RE: I'd like to know how to control the Neopixel LED.

Stian Røed Hafskjold — Wed, 23 Dec 2020 12:04:33 GMT

Hi, do you know if the code is running or not? Can you try to check with a simple application that just blinks an LED? You said that you want to "remove the bluetooth function"; does that mean that you are starting out with an example that uses the Softdevice? If so, did you remember to flash the Softdevice as well?

It is usually very helpful to use a logic analyzer to debug the digital interface between the nRF52 and the LED sensors. At least you can check to see if there is actually any data being transferred.