i2s_pdm sample
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Outline
#include <stdint.h>
#include <math.h>
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "driver/i2s_pdm.h"
#include "driver/gpio.h"
#include "esp_check.h"
#include "sdkconfig.h"
#include "i2s_pdm_example.h"
#include "i2s_example_pins.h"
#define EXAMPLE_PDM_TX_CLK_IO
#define EXAMPLE_PDM_TX_DOUT_IO
#define EXAMPLE_PDM_TX_FREQ_HZ
#define EXAMPLE_WAVE_AMPLITUDE
#define CONST_PI
#define EXAMPLE_SINE_WAVE_LEN
#define EXAMPLE_TONE_LAST_TIME_MS
#define EXAMPLE_BYTE_NUM_EVERY_TONE
tone
song
rhythm
tone_name
i2s_example_init_pdm_tx()
i2s_example_pdm_tx_task(void *)
Files
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SourceVuESP-IDF Framework and Examplesi2s_pdm samplemain/i2s_pdm_tx.c
 
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/* * SPDX-FileCopyrightText: 2021-2024 Espressif Systems (Shanghai) CO LTD * * SPDX-License-Identifier: Unlicense OR CC0-1.0 *//* ... */ #include <stdint.h> #include <math.h> #include "freertos/FreeRTOS.h" #include "freertos/task.h" #include "driver/i2s_pdm.h" #include "driver/gpio.h" #include "esp_check.h" #include "sdkconfig.h" #include "i2s_pdm_example.h" #include "i2s_example_pins.h"10 includes #define EXAMPLE_PDM_TX_CLK_IO EXAMPLE_I2S_BCLK_IO1 // I2S PDM TX clock io number #define EXAMPLE_PDM_TX_DOUT_IO EXAMPLE_I2S_DOUT_IO1 // I2S PDM TX data out io number #define EXAMPLE_PDM_TX_FREQ_HZ 16000 // I2S PDM TX frequency #define EXAMPLE_WAVE_AMPLITUDE (1000.0) // 1~32767 #define CONST_PI (3.1416f) #define EXAMPLE_SINE_WAVE_LEN(tone) (uint32_t)((EXAMPLE_PDM_TX_FREQ_HZ / (float)tone) + 0.5) // The sample point number per sine wave to generate the tone #define EXAMPLE_TONE_LAST_TIME_MS 500 #define EXAMPLE_BYTE_NUM_EVERY_TONE (EXAMPLE_TONE_LAST_TIME_MS * EXAMPLE_PDM_TX_FREQ_HZ / 1000)8 defines /* The frequency of tones: do, re, mi, fa, so, la, si, in Hz. */ static const uint32_t tone[3][7] = { {262, 294, 330, 349, 392, 440, 494}, // bass {523, 587, 659, 698, 784, 880, 988}, // alto {1046, 1175, 1318, 1397, 1568, 1760, 1976}, // treble }{...}; /* Numbered musical notation of 'twinkle twinkle little star' */ static const uint8_t song[28] = {1, 1, 5, 5, 6, 6, 5, 4, 4, 3, 3, 2, 2, 1, 5, 5, 4, 4, 3, 3, 2, 5, 5, 4, 4, 3, 3, 2 }{...}; /* Rhythm of 'twinkle twinkle little star', it's repeated in four sections */ static const uint8_t rhythm[7] = {1, 1, 1, 1, 1, 1, 2}; static const char *tone_name[3] = {"bass", "alto", "treble"}; static i2s_chan_handle_t i2s_example_init_pdm_tx(void) { i2s_chan_handle_t tx_chan; // I2S tx channel handler /* Setp 1: Determine the I2S channel configuration and allocate TX channel only * The default configuration can be generated by the helper macro, * it only requires the I2S controller id and I2S role, * but note that PDM channel can only be registered on I2S_NUM_0 *//* ... */ i2s_chan_config_t tx_chan_cfg = I2S_CHANNEL_DEFAULT_CONFIG(I2S_NUM_AUTO, I2S_ROLE_MASTER); tx_chan_cfg.auto_clear = true; ESP_ERROR_CHECK(i2s_new_channel(&tx_chan_cfg, &tx_chan, NULL)); /* Step 2: Setting the configurations of PDM TX mode and initialize the TX channel * The slot configuration and clock configuration can be generated by the macros * These two helper macros is defined in 'i2s_pdm.h' which can only be used in PDM TX mode. * They can help to specify the slot and clock configurations for initialization or re-configuring *//* ... */ i2s_pdm_tx_config_t pdm_tx_cfg = { #if CONFIG_EXAMPLE_PDM_TX_DAC .clk_cfg = I2S_PDM_TX_CLK_DAC_DEFAULT_CONFIG(EXAMPLE_PDM_TX_FREQ_HZ), /* The data bit-width of PDM mode is fixed to 16 */ .slot_cfg = I2S_PDM_TX_SLOT_DAC_DEFAULT_CONFIG(I2S_DATA_BIT_WIDTH_16BIT, I2S_SLOT_MODE_MONO),/* ... */ #else .clk_cfg = I2S_PDM_TX_CLK_DEFAULT_CONFIG(EXAMPLE_PDM_TX_FREQ_HZ), /* The data bit-width of PDM mode is fixed to 16 */ .slot_cfg = I2S_PDM_TX_SLOT_DEFAULT_CONFIG(I2S_DATA_BIT_WIDTH_16BIT, I2S_SLOT_MODE_MONO),/* ... */ #endif .gpio_cfg = { .clk = EXAMPLE_PDM_TX_CLK_IO, .dout = EXAMPLE_PDM_TX_DOUT_IO, .invert_flags = { .clk_inv = false, }{...}, }{...}, }{...}; ESP_ERROR_CHECK(i2s_channel_init_pdm_tx_mode(tx_chan, &pdm_tx_cfg)); /* Step 3: Enable the tx channel before writing data */ ESP_ERROR_CHECK(i2s_channel_enable(tx_chan)); return tx_chan; }{ ... } void i2s_example_pdm_tx_task(void *args) { int16_t *w_buf = (int16_t *)calloc(1, EXAMPLE_BUFF_SIZE); assert(w_buf); i2s_chan_handle_t tx_chan = i2s_example_init_pdm_tx(); size_t w_bytes = 0; uint8_t cnt = 0; // The current index of the song uint8_t tone_select = 0; // To selecting the tone level printf("Playing %s `twinkle twinkle little star`\n", tone_name[tone_select]); while (1) { int tone_point = EXAMPLE_SINE_WAVE_LEN(tone[tone_select][song[cnt] - 1]); /* Generate the tone buffer */ for (int i = 0; i < tone_point; i++) { w_buf[i] = (int16_t)((sin(2 * (float)i * CONST_PI / tone_point)) * EXAMPLE_WAVE_AMPLITUDE); }{...} for (int tot_bytes = 0; tot_bytes < EXAMPLE_BYTE_NUM_EVERY_TONE * rhythm[cnt % 7]; tot_bytes += w_bytes) { /* Play the tone */ if (i2s_channel_write(tx_chan, w_buf, tone_point * sizeof(int16_t), &w_bytes, 1000) != ESP_OK) { printf("Write Task: i2s write failed\n"); }{...} }{...} cnt++; /* If finished playing, switch the tone level */ if (cnt == sizeof(song)) { cnt = 0; tone_select++; tone_select %= 3; printf("Playing %s `twinkle twinkle little star`\n", tone_name[tone_select]); }{...} /* Gap between the tones */ vTaskDelay(15); }{...} free(w_buf); vTaskDelete(NULL); }{ ... }
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