RE: nRF52840 PDK - PDM - Where to call nrfx_pdm_buffer_set()?

Funkelfetisch — Thu, 30 May 2019 00:42:07 GMT

Hey Abdul,

did you ever manage to get your code working?

Best

RE: nRF52840 PDK - PDM - Where to call nrfx_pdm_buffer_set()?

abdulhaseeb — Mon, 11 Jun 2018 09:16:59 GMT

Hi,

I've updated the driver, however now I'm facing the problem that the buffer is not being updated with new values. I have a single buffer now (of 800 samples) that should be filled periodically. I'm trying to discontinue sampling as soon as the buffer is full, and then wait for the next cycle to start over again.

Please see the following code:

#include "stdint.h"
#include "stdbool.h"
#include "stdlib.h"
#include "string.h"

#include "nrf_assert.h"
#include "nrf_error.h"
#include "nrf_gpio.h"
#include "nrf_delay.h"

#include "pdm.h"
#include "nrfx_pdm.h"
#include "nrf_drv_pdm.h"
#include "nrf_pdm.h"

#include "math.h"

int                  sound_level = 0;
static volatile bool buffer_full = false;
int16_t buffer[BUFFER_SIZE];      

static void pdm_event_handler(nrfx_pdm_evt_t const * const p_evt)
{	

    ret_code_t err_code;

    if(p_evt->buffer_requested)
    {
        err_code =  nrfx_pdm_buffer_set(buffer, BUFFER_SIZE);
        APP_ERROR_CHECK(err_code);
    }

    if(p_evt->buffer_released)
    {
        
	/* Stop PDM */
        err_code = nrfx_pdm_stop();
        buffer_full = true;

        /* Process current buffer */
        int sum_of_squares = 0;
        int16_t *p_buffer_8 = (int16_t*)p_evt->buffer_released;

        for( int16_t i = 0 ; i < BUFFER_SIZE ; i++ )
        {
            sum_of_squares += p_buffer_8[0] * p_buffer_8[0];
            p_buffer_8++;
        }

        sound_level = sqrt(sum_of_squares / BUFFER_SIZE) ;


        /* Clear MIC power pin */
        nrf_gpio_pin_clear(MIC_PWR_CTRL);

        /* Configure DATA power pin */
        nrf_gpio_cfg_default(MIC_DATA);
        
    }
}

//get PDM buffer
uint32_t get_PDM_buffer(void)
{
    ret_code_t err_code;

    /* Set MIC power pin */
    nrf_gpio_pin_set(MIC_PWR_CTRL);

    /* Wait for 50ms (for Knowles microphone) to wake up. Add more delay afterwards to ignore useless data */
    //nrf_delay_ms(50);

    /* Start PDM */
    err_code = nrfx_pdm_start();
    APP_ERROR_CHECK(err_code);

    return err_code;
}


uint32_t drv_audio_enable(void)
{
    ret_code_t err_code;

    /* Set MIC power pin */
    nrf_gpio_pin_set(MIC_PWR_CTRL);

    /* Wait for 50ms (for Knowles microphone) to wake up. Add more delay afterwards to ignore useless data */
    nrf_delay_ms(50);

    err_code = nrfx_pdm_start();
    
    APP_ERROR_CHECK(err_code);

    while (!buffer_full)
    {
      __WFE();
    }
    buffer_full = false;

    return err_code;
}


uint32_t drv_audio_disable(void)
{
    ret_code_t err_code;

    /* Clear MIC power pin */
    nrf_gpio_pin_clear(MIC_PWR_CTRL);

    /* Configure DATA power pin */
    nrf_gpio_cfg_default(MIC_DATA);

    return err_code;
}


uint32_t drv_audio_init(void)
{
    nrfx_pdm_config_t pdm_cfg = NRFX_PDM_DEFAULT_CONFIG(MIC_CLK, MIC_DATA);

    pdm_cfg.gain_l          = CONFIG_AUDIO_PDM_GAIN;
    pdm_cfg.gain_r          = CONFIG_AUDIO_PDM_GAIN;

    return nrf_drv_pdm_init(&pdm_cfg, pdm_event_handler);
}

RE: nRF52840 PDK - PDM - Where to call nrfx_pdm_buffer_set()?

Stian Røed Hafskjold — Thu, 07 Jun 2018 14:17:11 GMT

Hi, sorry for the late response. Did you find a solution, or do you still need help?