Integration of PDM microphone with thingy53

[Rakshita]

I want to integrate the PDM microphone with thingy53, I found no particular sample code for it

Would be needing help from scratch

[Rakshita]

I have executed some code till now

#include <zephyr/zephyr.h>
#include <stdio.h>
#include <zephyr/drivers/uart.h>
#include <string.h>
// #include <misc/printk.h>

#include <nrfx_pdm.h>
#include <hal/nrf_gpio.h>
#include "nrf5340_application.h"
// #include <nrf9160.h>
// #include <nrf53.h>

#define PDM_BUF_SIZE 3072  //length of buffer in 16 bit words

int16_t pdm_buf[PDM_BUF_SIZE];


void bsd_recoverable_error_handler(uint32_t err)
{
	printk("bsdlib recoverable error: %u\n", err);
}

void nrfx_pdm_event_handler(nrfx_pdm_evt_t const *const p_evt)
{
	if (p_evt->buffer_requested) {
                printk("Entered into 1st if condition \n");
		nrfx_pdm_buffer_set(pdm_buf, PDM_BUF_SIZE);
	}
	if (p_evt->buffer_released != 0) {
		// printk("Out: %4x @ 0x%x\r\n %4x @ 0x%x\r\n",
		//        (uint16_t)pdm_buf[0], &pdm_buf[0],
		//        (uint16_t)pdm_buf[1], &pdm_buf[1]);
                printk("Entered into 2nd if condition \n");
                for (int i = 0; i < 8; i++) {
                        printk("%4x \n", (uint16_t)pdm_buf[i]);
                }
                printk("\r\n");
	}
}

static void pdm_init(void)
{
	nrfx_pdm_config_t pdm_config = NRFX_PDM_DEFAULT_CONFIG(NULL, NULL);
	nrfx_pdm_init(&pdm_config, nrfx_pdm_event_handler);
}

/*ISR workaround given by Nordic*/
ISR_DIRECT_DECLARE(pdm_isr_handler)
{
	nrfx_pdm_irq_handler();
	ISR_DIRECT_PM(); /* PM done after servicing interrupt for best latency
			  */

	return 1; /* We should check if scheduling decision should be made */
}

void main(void)
{
	printk("The AT host sample started\n");
	IRQ_DIRECT_CONNECT(PDM0_IRQn, 0, pdm_isr_handler, 0);  //workaround line 
	printk("Starting PDM program!\n");
	printk("PDM Buffer size: %d in 16 bit words\n", PDM_BUF_SIZE);

	/*
	bool enabled = nrfx_pdm_enable_check();
	printk(enabled ? "true/n" : "false\n");
	*/

	pdm_init();
	printk("%4x is the starting address\n", &pdm_buf);
	// printk("%4x is current value at %x\n", pdm_buf[0], &pdm_buf);
	printk("The PDM will start reading NOW...\n");
      /*  for (int i = 0; i < 500; i++) {
          int k = 5;
          for (volatile int j = 0; j < 50; j++) {
                k = !k;
		}
	}*/
	nrfx_pdm_start();
	for (int i = 0; i < 100; i++) {
                int k = 5;
                for (volatile int j = 0; j < 100; j++) {
                        k = !k;
                }
	}
	nrfx_pdm_stop();
        printk("%4x is current value at %x\n", (uint16_t)pdm_buf[0], &pdm_buf);

	
}

[Rakshita]

But the output is repeating and I don't think so the microphone is able to identify any sound as the output should have been changing

[Rakshita]

I check the device tree file and in that I noticed that pdm clk and data in pin is not assigned and when I tried to add assignment there was no option for &pdm