73 lines
2.5 KiB
C
73 lines
2.5 KiB
C
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/* I2S Example
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This example code will output 100Hz sine wave and triangle wave to 2-channel of I2S driver
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This example code is in the Public Domain (or CC0 licensed, at your option.)
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Unless required by applicable law or agreed to in writing, this
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software is distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR
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CONDITIONS OF ANY KIND, either express or implied.
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*/
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#include <stdio.h>
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#include "freertos/FreeRTOS.h"
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#include "freertos/task.h"
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#include "esp_system.h"
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#include "nvs_flash.h"
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#include "driver/i2s.h"
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#include <math.h>
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#define SAMPLE_RATE (36000)
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#define I2S_NUM (0)
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#define WAVE_FREQ_HZ (100)
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#define PI 3.14159265
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#define SAMPLE_PER_CYCLE (SAMPLE_RATE/WAVE_FREQ_HZ)
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void app_main()
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{
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unsigned int i, sample_val;
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float sin_float, triangle_float, triangle_step = 65536.0 / SAMPLE_PER_CYCLE;
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//for 36Khz sample rates, we create 100Hz sine wave, every cycle need 36000/100 = 360 samples (4-bytes each sample)
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//using 6 buffers, we need 60-samples per buffer
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//2-channels, 16-bit each channel, total buffer is 360*4 = 1440 bytes
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i2s_config_t i2s_config = {
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.mode = I2S_MODE_MASTER | I2S_MODE_TX, // Only TX
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.sample_rate = SAMPLE_RATE,
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.bits_per_sample = 16, //16-bit per channel
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.channel_format = I2S_CHANNEL_FMT_RIGHT_LEFT, //2-channels
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.communication_format = I2S_COMM_FORMAT_I2S | I2S_COMM_FORMAT_I2S_MSB,
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.dma_buf_count = 6,
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.dma_buf_len = 60, //
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.intr_alloc_flags = ESP_INTR_FLAG_LEVEL1 //Interrupt level 1
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};
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i2s_pin_config_t pin_config = {
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.bck_io_num = 26,
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.ws_io_num = 25,
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.data_out_num = 22,
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.data_in_num = -1 //Not used
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};
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nvs_flash_init();
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i2s_driver_install(I2S_NUM, &i2s_config, 0, NULL);
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i2s_set_pin(I2S_NUM, &pin_config);
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triangle_float = -32767;
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for(i = 0; i < SAMPLE_PER_CYCLE; i++) {
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sin_float = sin(i * PI / 180.0);
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if(sin_float >= 0)
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triangle_float += triangle_step;
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else
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triangle_float -= triangle_step;
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sin_float *= 32767;
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sample_val = 0;
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sample_val += (short)triangle_float;
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sample_val = sample_val << 16;
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sample_val += (short) sin_float;
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i2s_push_sample(I2S_NUM, (char *)&sample_val, portMAX_DELAY);
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}
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}
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