114 lines
3.8 KiB
C
114 lines
3.8 KiB
C
/* 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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Every 5 seconds, it will change bits_per_sample [16, 24, 32] for i2s data
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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 "driver/i2s.h"
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#include "esp_system.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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static void setup_triangle_sine_waves(int bits)
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{
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int *samples_data = malloc(((bits+8)/16)*SAMPLE_PER_CYCLE*4);
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unsigned int i, sample_val;
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double sin_float, triangle_float, triangle_step = (double) pow(2, bits) / SAMPLE_PER_CYCLE;
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size_t i2s_bytes_write = 0;
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printf("\r\nTest bits=%d free mem=%d, written data=%d\n", bits, esp_get_free_heap_size(), ((bits+8)/16)*SAMPLE_PER_CYCLE*4);
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triangle_float = -(pow(2, bits)/2 - 1);
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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 *= (pow(2, bits)/2 - 1);
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if (bits == 16) {
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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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samples_data[i] = sample_val;
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} else if (bits == 24) { //1-bytes unused
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samples_data[i*2] = ((int) triangle_float) << 8;
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samples_data[i*2 + 1] = ((int) sin_float) << 8;
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} else {
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samples_data[i*2] = ((int) triangle_float);
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samples_data[i*2 + 1] = ((int) sin_float);
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}
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}
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i2s_set_clk(I2S_NUM, SAMPLE_RATE, bits, 2);
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//Using push
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// for(i = 0; i < SAMPLE_PER_CYCLE; i++) {
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// if (bits == 16)
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// i2s_push_sample(0, &samples_data[i], 100);
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// else
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// i2s_push_sample(0, &samples_data[i*2], 100);
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// }
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// or write
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i2s_write(I2S_NUM, samples_data, ((bits+8)/16)*SAMPLE_PER_CYCLE*4, &i2s_bytes_write, 100);
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free(samples_data);
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}
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void app_main()
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{
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//for 36Khz sample rates, we create 100Hz sine wave, every cycle need 36000/100 = 360 samples (4-bytes or 8-bytes each sample)
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//depend on bits_per_sample
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//using 6 buffers, we need 60-samples per buffer
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//if 2-channels, 16-bit each channel, total buffer is 360*4 = 1440 bytes
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//if 2-channels, 24/32-bit each channel, total buffer is 360*8 = 2880 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,
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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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.use_apll = false,
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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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i2s_driver_install(I2S_NUM, &i2s_config, 0, NULL);
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i2s_set_pin(I2S_NUM, &pin_config);
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int test_bits = 16;
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while (1) {
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setup_triangle_sine_waves(test_bits);
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vTaskDelay(5000/portTICK_RATE_MS);
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test_bits += 8;
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if(test_bits > 32)
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test_bits = 16;
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}
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}
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