Adafruit I2S MEMS Microphone Breakout with the NRF9160 DK

[Nahom Abraha]

Hello,

I am working on a project where I can have Voice over IP on the NRF9160 DK. I am now working with a I2S microphone (https://www.adafruit.com/product/3421) at the moment I have trouble programming I2S. I read the I2S documentation on the zephyr website but I have still trouble understanding it and there is also no example where I can look at. I don't know how to setup the struct device (https://docs.zephyrproject.org/2.0.0/reference/peripherals/i2s.html?highlight=i2s#) that you use in the functions to setup i2s and read/write the buffer. I also don't know which pin i have to connect to the microphone, because the pin names are not the same or can i just connect  to any pin and write in the code to use that pin? If sombody has an I2S example I would really appreciate that. I also need to find a speaker that I can use any suggestions?

Thank you in advance

[Nahom Abraha]

Hi Martin,

I changed the files and the i2s_configure still doesn't work. I found out that the device_get_binding returns a null pointer so the i2s_device is probably the problem. Is it possible that I have the wrong driver name or that i2s is still disabled. I enabled i2s in the prj.conf CONFIG_I2S=y so that shouldn't be the problem.

Thank you in advance

[Martin Lesund]

Please check out this Devzone thread: https://devzone.nordicsemi.com/f/nordic-q-a/60256/i2s-on-nrf9160

[Nahom Abraha]

I am using now the nrfx_i2s driver. I asked a question about the i2s in this thread   https://devzone.nordicsemi.com/f/nordic-q-a/60256/i2s-on-nrf9160 can you please check it out.

thank you

[Nahom Abraha]

Hi Martin,

So I am using now the nrfx_i2s driver I changed the code and I don't receive any data. I think that the problem is with the datahandler. The microphone(https://www.adafruit.com/product/3421) works with a raspberry pi so the microphone works.I don't know how to fix this. I connected
LRCL with pin 8
DOUT with 9
BCLK with pin 10

#include <nrf.h>
#include <zephyr.h>
#include <device.h>
#include <sys/printk.h>
#include <stdbool.h>
#include <nrfx_i2s.h>
#include <string.h>

#include "microphone.h"
#include "button.h"
#include "udp.h"

#define  I2S_BUFFER_SIZE 1024
#define  SCK_PIN    10 
#define  SDIN_PIN   9
#define  LRCK_PIN   8
#define  MCK_PIN    7
#define  SDOUT_PIN  6 

int counter;
static uint32_t rx_buffer[I2S_BUFFER_SIZE]={0};
static uint32_t tx_buffer[I2S_BUFFER_SIZE]={0};
static nrfx_i2s_buffers_t buffer;   
 
ISR_DIRECT_DECLARE(i2s_isr_handler) 
{
  nrfx_i2s_irq_handler();
  ISR_DIRECT_PM();

  return 1; 
}

static void data_handler(nrfx_i2s_buffers_t const * p_released, uint32_t status)
{ 
  if (NRFX_I2S_STATUS_NEXT_BUFFERS_NEEDED == status)
  {
    printk("%u\n",status);
    nrfx_err_t err = nrfx_i2s_next_buffers_set(&buffer);
    if (err != NRFX_SUCCESS ) {
        printk("next buffer failed with error code:%d\n",err);
      } 
  }

  if(p_released != NULL){
    if (p_released->p_rx_buffer != NULL)
    {
        //uint8_t* data=p_released->p_rx_buffer;
        //data[0] == p_released->p_rx_buffer[0]
        uint8_t data[I2S_BUFFER_SIZE]={0};
        memcpy(data,p_released->p_rx_buffer, sizeof(p_released->p_rx_buffer));
        for(int i=0; i <1024; i++)
        {
            printk("data: 0x%hhX\n",data[i]);
            printk("data2:0x%hhX\n",p_released->p_rx_buffer[i]);
        }
      }
    }
  }
}

void recordaudio(void)
{
  printk("Start i2s configuration\n");
  nrfx_err_t err;
  uint16_t buffer_size=2048;
  nrfx_i2s_config_t config = NRFX_I2S_DEFAULT_CONFIG(SCK_PIN,LRCK_PIN,MCK_PIN,SDOUT_PIN,SDIN_PIN);
  
  buffer.p_rx_buffer=rx_buffer;
  buffer.p_tx_buffer=tx_buffer;

 //config.irq_priority = NRFX_I2S_DEFAULT_CONFIG_IRQ_PRIORITY;
// config.mode = NRF_I2S_MODE_MASTER;
// config.mck_setup = NRF_I2S_MCK_32MDIV8;
// config.channels = NRF_I2S_CHANNELS_LEFT;
// config.sample_width = NRF_I2S_SWIDTH_16BIT;
// config.ratio = NRF_I2S_RATIO_32X;
// config.format = NRF_I2S_FORMAT_I2S;
// config.alignment=NRF_I2S_ALIGN_LEFT;
//  
 IRQ_DIRECT_CONNECT(I2S_IRQn, 0,i2s_isr_handler, 0);

  err = nrfx_i2s_init(&config, data_handler);
  if (err != NRFX_SUCCESS)
  {
      printk("i2s init failed:%d\n",err);
  }
  printk("i2s_start\n");
  err=nrfx_i2s_start(&buffer,buffer_size, 0);
  if(err!=NRFX_SUCCESS )
    {
     printk("i2s start failed with error:%d\n",err);
    }
  while(1)
     {
      printk("recording\n");
      k_sleep(2000);
     }
    printk("\n stop recording \n");
    nrfx_i2s_stop();
    nrfx_i2s_uninit();
}

[Martin Lesund]

Hi Nahom,

Please try to assign other pins since 8 and 9 are used on switch 1 & switch 2 on the nrf91DK.

Look at the documentation at which pins that are available: https://infocenter.nordicsemi.com/index.jsp?topic=%2Fug_nrf91_dk%2FUG%2Fnrf91_DK%2Fif_connector.html