ESP32 Forum

I like things small and digital, so its not for me. I can see the appeal though - good luck!

hope for the digi tiny ICS boards asap

hope for the digi tiny ICS boards asap

Already packaged, will send them out tomorrow!

Here is a complete example, I verified it works:

Code: Select all

/*
 * app_main.c
 *
 *  Created on: 30.03.2017
 *      Author: michaelboeckling
 */

#include <stdlib.h>
#include <stddef.h>
#include <inttypes.h>
#include <string.h>
#include <stdio.h>
#include <stdbool.h>
#include <sys/time.h>

#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "freertos/event_groups.h"
#include "esp_system.h"
#include "esp_log.h"
#include "driver/i2s.h"

#define TAG "main"

static void init_i2s()
{
	const int sample_rate = 44100;

	/* TX: I2S_NUM_0 */
    i2s_config_t i2s_config_tx = {
	.mode = I2S_MODE_MASTER | I2S_MODE_TX,
	.sample_rate = sample_rate,
	.bits_per_sample = I2S_BITS_PER_SAMPLE_16BIT,
	.channel_format = I2S_CHANNEL_FMT_RIGHT_LEFT,   // 2-channels
	.communication_format = I2S_COMM_FORMAT_I2S_MSB,
	.dma_buf_count = 32,                            // number of buffers, 128 max.
	.dma_buf_len = 32 * 2,                          // size of each buffer
	.intr_alloc_flags = ESP_INTR_FLAG_LEVEL1        // Interrupt level 1
    };

    i2s_pin_config_t pin_config_tx = {
			.bck_io_num = GPIO_NUM_26,
			.ws_io_num = GPIO_NUM_25,
			.data_out_num = GPIO_NUM_22,
			.data_in_num = GPIO_NUM_23
	};
    i2s_driver_install(I2S_NUM_0, &i2s_config_tx, 0, NULL);
    i2s_set_pin(I2S_NUM_0, &pin_config_tx);


    /* RX: I2S_NUM_1 */
    i2s_config_t i2s_config_rx = {
	.mode = I2S_MODE_MASTER | I2S_MODE_RX, // Only TX
	.sample_rate = sample_rate,
	.bits_per_sample = I2S_BITS_PER_SAMPLE_32BIT,    // Only 8-bit DAC support
	.channel_format = I2S_CHANNEL_FMT_RIGHT_LEFT,   // 2-channels
	.communication_format = I2S_COMM_FORMAT_I2S_MSB,
	.dma_buf_count = 32,                            // number of buffers, 128 max.
	.dma_buf_len = 32 * 2,                          // size of each buffer
	.intr_alloc_flags = ESP_INTR_FLAG_LEVEL1        // Interrupt level 1
	};

	i2s_pin_config_t pin_config_rx = {
		.bck_io_num = GPIO_NUM_17,
		.ws_io_num = GPIO_NUM_18,
		.data_out_num = I2S_PIN_NO_CHANGE,
		.data_in_num = GPIO_NUM_5
	};

	i2s_driver_install(I2S_NUM_1, &i2s_config_rx, 0, NULL);
	i2s_set_pin(I2S_NUM_1, &pin_config_rx);

}


void task_megaphone(void *pvParams)
{
	uint16_t buf_len = 1024;
	char *buf = calloc(buf_len, sizeof(char));

	struct timeval tv = {0};
	struct timezone *tz = {0};
	gettimeofday(&tv, &tz);
	uint64_t micros = tv.tv_usec + tv.tv_sec * 1000000;
	uint64_t micros_prev = micros;
	uint64_t delta = 0;

	init_i2s();

	int cnt = 0;
	int bytes_written = 0;

	while(1)
	{
		char *buf_ptr_read = buf;
		char *buf_ptr_write = buf;

		// read whole block of samples
		int bytes_read = 0;
		while(bytes_read == 0) {
			bytes_read = i2s_read_bytes(I2S_NUM_1, buf, buf_len, 0);
		}

		uint32_t samples_read = bytes_read / 2 / (I2S_BITS_PER_SAMPLE_32BIT / 8);

		//  convert 2x 32 bit stereo -> 1 x 16 bit mono
		for(int i = 0; i < samples_read; i++) {

			// const char samp32[4] = {ptr_l[0], ptr_l[1], ptr_r[0], ptr_r[1]};

			// left
			buf_ptr_write[0] = buf_ptr_read[2]; // mid
			buf_ptr_write[1] = buf_ptr_read[3]; // high

			// right
			buf_ptr_write[2] = buf_ptr_write[0]; // mid
			buf_ptr_write[3] = buf_ptr_write[1]; // high


			buf_ptr_write += 2 * (I2S_BITS_PER_SAMPLE_16BIT / 8);
			buf_ptr_read += 2 * (I2S_BITS_PER_SAMPLE_32BIT / 8);
		}

		// local echo
		bytes_written = samples_read * 2 * (I2S_BITS_PER_SAMPLE_16BIT / 8);
		i2s_write_bytes(I2S_NUM_0, buf, bytes_written, portMAX_DELAY);

		cnt += samples_read;

		if(cnt >= 44100) {
			gettimeofday(&tv, &tz);
			micros = tv.tv_usec + tv.tv_sec * 1000000;
			delta = micros - micros_prev;
			micros_prev = micros;
			printf("%d samples in %" PRIu64 " usecs\n", cnt, delta);

			cnt = 0;
		}
	}
}

/**
 * entry point
 */
void app_main()
{
    printf("starting app_main()\n");
    xTaskCreatePinnedToCore(&task_megaphone, "task_megaphone", 16384, NULL, 20, NULL, 0);
}

        int bytes_read = 0;
        while(bytes_read == 0) {
            bytes_read = i2s_read_bytes(I2S_NUM_1, buf, sizeof(buf), portMAX_DELAY);
        }

        uint32_t samples_read = bytes_read / (I2S_BITS_PER_SAMPLE_32BIT / 8);

        for (int i = 0; i < samples_read; i++)
        {
            buf_ptr_write[0] = buf_ptr_read[2]; // mid
            buf_ptr_write[1] = buf_ptr_read[3]; // high        
        }

        int bytes_written = samples_read * (I2S_BITS_PER_SAMPLE_32BIT / 8);

        i2s_write_bytes(I2S_NUM_0, (const char*)buf, bytes_written, portMAX_DELAY);

1. i'd like to try this with a different i2s mems microhone. ( any suggestions, i'm using adafruit's SPH0645 )

2. any idea's why setting the communication_format to I2S_COMM_FORMAT_RAW_I2S would have this benefit and is there a way to tweak this further ?

typedef enum {
    I2S_COMM_FORMAT_I2S         = 0x01, /*!< I2S communication format I2S*/
    I2S_COMM_FORMAT_I2S_MSB     = 0x02, /*!< I2S format MSB*/
    I2S_COMM_FORMAT_I2S_LSB     = 0x04, /*!< I2S format LSB*/
    I2S_COMM_FORMAT_PCM         = 0x08, /*!< I2S communication format PCM*/
    I2S_COMM_FORMAT_PCM_SHORT   = 0x10, /*!< PCM Short*/
    I2S_COMM_FORMAT_PCM_LONG    = 0x20, /*!< PCM Long*/
} i2s_comm_format_t;