wave_gen.c File Reference

#include <math.h>
#include <string.h>
#include "sdkconfig.h"
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "driver/i2s_std.h"
#include "esp_log.h"
#include "esp_check.h"
#include "wave_gen.h"

Include dependency graph for wave_gen.c:

Go to the source code of this file.

Macros
#define	WAVE_GEN_HAS_SDM   0
#define	I2S_BUFFER_SIZE   1024
#define	DEFAULT_SAMPLE_RATE   44100
#define	I2S_BUFFER_SIZE   1024
#define	DEFAULT_SAMPLE_RATE   44100
#define	PI   3.14159265358979323846f

Functions
static void	wave_gen_task (void *args)
esp_err_t	wave_gen_init (const wave_gen_config_t *config)
	Initialize the Wave Generator component.
esp_err_t	wave_gen_start (void)
	Start the wave generation task.
esp_err_t	wave_gen_stop (void)
	Stop the wave generation task.
void	wave_gen_set_freq (float freq_hz)
	Set the frequency of the generated wave.
void	wave_gen_set_type (wave_type_t type)
	Set the waveform type.
void	wave_gen_set_volume (float volume)
	Set the output volume/amplitude.
esp_err_t	wave_gen_sdm_start (void)
	Start the SDM sine generator (uses CONFIG_SDM_* settings).
esp_err_t	wave_gen_sdm_stop (void)
	Stop the SDM sine generator.

Variables
static const char *	TAG = "wave_gen"
static i2s_chan_handle_t	tx_conn_handle = NULL
static TaskHandle_t	s_wave_task_handle = NULL
static bool	s_running = false
static float	s_frequency = 440.0f
static float	s_volume = 0.5f
static wave_type_t	s_type = WAVE_TYPE_SINE
static uint32_t	s_sample_rate = 44100
static float	s_phase = 0.0f

Macro Definition Documentation

DEFAULT_SAMPLE_RATE [1/2]

#define DEFAULT_SAMPLE_RATE   44100

Definition at line 34 of file wave_gen.c.

DEFAULT_SAMPLE_RATE [2/2]

#define DEFAULT_SAMPLE_RATE   44100

Definition at line 34 of file wave_gen.c.

I2S_BUFFER_SIZE [1/2]

#define I2S_BUFFER_SIZE   1024

Definition at line 33 of file wave_gen.c.

I2S_BUFFER_SIZE [2/2]

#define I2S_BUFFER_SIZE   1024

Definition at line 33 of file wave_gen.c.

Referenced by wave_gen_task().

PI

#define PI   3.14159265358979323846f

Definition at line 37 of file wave_gen.c.

Referenced by wave_gen_task().

WAVE_GEN_HAS_SDM

#define WAVE_GEN_HAS_SDM   0

Definition at line 28 of file wave_gen.c.

Function Documentation

wave_gen_init()

esp_err_t wave_gen_init

(

const wave_gen_config_t *

config

)

Initialize the Wave Generator component.

Parameters

config

Pointer to configuration structure

Returns

esp_err_t ESP_OK on success

Definition at line 213 of file wave_gen.c.

{
    if (tx_conn_handle) {
        ESP_LOGW(TAG, "Already initialized");
        return ESP_OK;
    }
 
    ESP_LOGI(TAG, "Initializing I2S Wave Gen (32-bit) on BCK:%d WS:%d DO:%d MCK:%d",
             config->bck_io_num, config->ws_io_num, config->data_out_num, config->mck_io_num);
 
    i2s_chan_config_t chan_cfg = I2S_CHANNEL_DEFAULT_CONFIG(I2S_NUM_AUTO, I2S_ROLE_MASTER);
    ESP_RETURN_ON_ERROR(i2s_new_channel(&chan_cfg, &tx_conn_handle, NULL), TAG, "Failed to create I2S channel");
 
    i2s_std_config_t std_cfg = {
        .clk_cfg = I2S_STD_CLK_DEFAULT_CONFIG(config->sample_rate),
        .slot_cfg = I2S_STD_PCM_SLOT_DEFAULT_CONFIG(I2S_DATA_BIT_WIDTH_32BIT, I2S_SLOT_MODE_STEREO),
        .gpio_cfg = {
            .mclk = config->mck_io_num, // Can be I2S_GPIO_UNUSED (-1)
            .bclk = config->bck_io_num,
            .ws = config->ws_io_num,
            .dout = config->data_out_num,
            .din = I2S_GPIO_UNUSED,
            .invert_flags = {
                .mclk_inv = false,
                .bclk_inv = false,
                .ws_inv = false,
            },
        },
    };
    
    // Some PCM5102 modules benefit from MCLK being enabled if wired, 
    // but often they generate it internally from BCK if MCLK is floating/grounded.
    // The driver will handle pin configuration.
 
    ESP_RETURN_ON_ERROR(i2s_channel_init_std_mode(tx_conn_handle, &std_cfg), TAG, "Failed to init I2S std mode");
 
    s_sample_rate = config->sample_rate;
    return ESP_OK;
}

References wave_gen_config_t::bck_io_num, wave_gen_config_t::data_out_num, ESP_OK, ESP_RETURN_ON_ERROR, wave_gen_config_t::mck_io_num, s_sample_rate, wave_gen_config_t::sample_rate, TAG, tx_conn_handle, and wave_gen_config_t::ws_io_num.

Referenced by app_main().

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wave_gen_sdm_start()

esp_err_t wave_gen_sdm_start

(

void

)

Start the SDM sine generator (uses CONFIG_SDM_* settings).

Returns

esp_err_t ESP_OK on success

Definition at line 303 of file wave_gen.c.

{
#if WAVE_GEN_HAS_SDM
    if (s_sdm_running) {
        return ESP_OK;
    }
    ESP_LOGI(TAG, "Starting SDM sine on GPIO %d at %d Hz", CONFIG_SDM_GPIO, CONFIG_SDM_FREQ_HZ);
    ESP_RETURN_ON_ERROR(sdm_init((uint32_t)CONFIG_SDM_FREQ_HZ), TAG, "SDM init failed");
    s_sdm_running = true;
    return ESP_OK;
#else
    return ESP_ERR_NOT_SUPPORTED;
#endif
}

References ESP_OK, ESP_RETURN_ON_ERROR, and TAG.

Referenced by app_main().

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wave_gen_sdm_stop()

esp_err_t wave_gen_sdm_stop

(

void

)

Stop the SDM sine generator.

Returns

esp_err_t ESP_OK on success

Definition at line 318 of file wave_gen.c.

{
#if WAVE_GEN_HAS_SDM
    if (!s_sdm_running) {
        return ESP_OK;
    }
    s_sdm_running = false;
    sdm_deinit();
    return ESP_OK;
#else
    return ESP_ERR_NOT_SUPPORTED;
#endif
}

References ESP_OK.

wave_gen_set_freq()

void wave_gen_set_freq

(

float

freq_hz

)

Set the frequency of the generated wave.

Parameters

freq_hz

Frequency in Hertz

Definition at line 284 of file wave_gen.c.

{
    if (freq_hz < 1.0f) freq_hz = 1.0f;
    if (freq_hz > (float)s_sample_rate / 2.0f) freq_hz = (float)s_sample_rate / 2.0f;
    s_frequency = freq_hz;
}

References s_frequency, and s_sample_rate.

wave_gen_set_type()

void wave_gen_set_type

(

wave_type_t

type

)

Set the waveform type.

Parameters

type	One of wave_type_t

Definition at line 291 of file wave_gen.c.

{
    s_type = type;
}

References s_type.

Referenced by app_main().

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wave_gen_set_volume()

void wave_gen_set_volume

(

float

volume

)

Set the output volume/amplitude.

Parameters

volume

0.0 to 1.0 (clamped)

Definition at line 296 of file wave_gen.c.

{
    if (volume < 0.0f) volume = 0.0f;
    if (volume > 1.0f) volume = 1.0f;
    s_volume = volume;
}

References s_volume.

Referenced by app_main().

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wave_gen_start()

esp_err_t wave_gen_start

(

void

)

Start the wave generation task.

Returns

esp_err_t ESP_OK on success

Definition at line 253 of file wave_gen.c.

{
    if (!tx_conn_handle) return ESP_FAIL;
    if (s_running) return ESP_OK;
 
    ESP_RETURN_ON_ERROR(i2s_channel_enable(tx_conn_handle), TAG, "Failed to enable channel");
    
    s_running = true;
    xTaskCreate(wave_gen_task, "wave_gen_task", 4096, NULL, 5, &s_wave_task_handle);
    ESP_LOGI(TAG, "Wave Gen Started");
    return ESP_OK;
}

References ESP_OK, ESP_RETURN_ON_ERROR, s_running, s_wave_task_handle, TAG, tx_conn_handle, and wave_gen_task().

Referenced by app_main().

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wave_gen_stop()

esp_err_t wave_gen_stop

(

void

)

Stop the wave generation task.

Returns

esp_err_t ESP_OK on success

Definition at line 266 of file wave_gen.c.

{
    if (!s_running) return ESP_OK;
    s_running = false;
    // Wait for task or just let it spin down? 
    // For simplicity, we assume task sees s_running false and exits.
    // Ideally we'd join or wait.
    
    // Allow task to exit loop
    vTaskDelay(pdMS_TO_TICKS(100)); 
 
    if (tx_conn_handle) {
        i2s_channel_disable(tx_conn_handle);
    }
    ESP_LOGI(TAG, "Wave Gen Stopped");
    return ESP_OK;
}

References ESP_OK, s_running, TAG, and tx_conn_handle.

wave_gen_task()

void wave_gen_task ( void * args )

static

Definition at line 146 of file wave_gen.c.

{
    size_t w_bytes = 0;
    // Stereo buffer (Left + Right interleaving)
    // Using 32-bit samples for high resolution
    int32_t *samples = (int32_t *)malloc(I2S_BUFFER_SIZE * 2 * sizeof(int32_t));
    if (!samples) {
        ESP_LOGE(TAG, "Failed to allocate audio buffer");
        vTaskDelete(NULL);
        return;
    }
 
    float phase_inc = 0.0f;
    
    while (s_running) {
        // Recalculate phase increment per block to allow dynamic frequency changes
        // phase goes from 0.0f to 1.0f
        if (s_sample_rate > 0) {
            phase_inc = s_frequency / (float)s_sample_rate;
        }
 
        // Fill buffer
        for (int i = 0; i < I2S_BUFFER_SIZE; i++) {
            float sample_val = 0.0f;
 
            switch (s_type) {
                case WAVE_TYPE_SINE:
                    sample_val = sinf(s_phase * 2.0f * PI);
                    break;
                case WAVE_TYPE_SQUARE:
                    sample_val = (s_phase < 0.5f) ? 1.0f : -1.0f;
                    break;
                case WAVE_TYPE_TRIANGLE:
                    sample_val = (s_phase < 0.5f) ? (4.0f * s_phase - 1.0f) : (3.0f - 4.0f * s_phase);
                    break;
                case WAVE_TYPE_SAWTOOTH:
                    sample_val = 2.0f * s_phase - 1.0f;
                    break;
            }
 
            // Apply volume and scale to 32-bit signed integer range
            // Max positive: 2147483647
            int32_t pcm_val = (int32_t)(sample_val * s_volume * 2147483647.0f);
 
            // Interleaved Stereo (Left = Right)
            samples[i * 2] = pcm_val;
            samples[i * 2 + 1] = pcm_val;
 
            // Advance phase
            s_phase += phase_inc;
            if (s_phase >= 1.0f) {
                s_phase -= 1.0f;
            }
        }
 
        // Write to I2S
        /* Because we are writing to a standard I2S channel, we should ensure the format matches the config */
        if (i2s_channel_write(tx_conn_handle, samples, I2S_BUFFER_SIZE * 2 * sizeof(int32_t), &w_bytes, portMAX_DELAY) != ESP_OK) {
            ESP_LOGW(TAG, "I2S Write Failed");
        }
    }
 
    free(samples);
    vTaskDelete(NULL);
    s_wave_task_handle = NULL;
}

References ESP_OK, I2S_BUFFER_SIZE, PI, s_frequency, s_phase, s_running, s_sample_rate, s_type, s_volume, s_wave_task_handle, TAG, tx_conn_handle, WAVE_TYPE_SAWTOOTH, WAVE_TYPE_SINE, WAVE_TYPE_SQUARE, and WAVE_TYPE_TRIANGLE.

Referenced by wave_gen_start().

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Variable Documentation

s_frequency

float s_frequency = 440.0f

static

Definition at line 44 of file wave_gen.c.

Referenced by wave_gen_set_freq(), and wave_gen_task().

s_phase

float s_phase = 0.0f

static

Definition at line 48 of file wave_gen.c.

Referenced by wave_gen_task().

s_running

bool s_running = false

static

Definition at line 41 of file wave_gen.c.

Referenced by wave_gen_start(), wave_gen_stop(), and wave_gen_task().

s_sample_rate

uint32_t s_sample_rate = 44100

static

Definition at line 47 of file wave_gen.c.

Referenced by wave_gen_init(), wave_gen_set_freq(), and wave_gen_task().

s_type

wave_type_t s_type = WAVE_TYPE_SINE

static

Definition at line 46 of file wave_gen.c.

Referenced by wave_gen_set_type(), and wave_gen_task().

s_volume

float s_volume = 0.5f

static

Definition at line 45 of file wave_gen.c.

Referenced by wave_gen_set_volume(), and wave_gen_task().

s_wave_task_handle

TaskHandle_t s_wave_task_handle = NULL

static

Definition at line 40 of file wave_gen.c.

Referenced by wave_gen_start(), and wave_gen_task().

TAG

const char* TAG = "wave_gen"

static

Definition at line 31 of file wave_gen.c.

tx_conn_handle

i2s_chan_handle_t tx_conn_handle = NULL

static

Definition at line 39 of file wave_gen.c.

Referenced by wave_gen_init(), wave_gen_start(), wave_gen_stop(), and wave_gen_task().