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