#include <driver/i2s.h>

#define I2S_SAMPLE_RATE 78125

#define ADC_INPUT ADC1_CHANNEL_4 //pin 32

#define OUTPUT_PIN 27

#define OUTPUT_VALUE 3800

#define READ_DELAY 10000 //microseconds

void i2sInit()

{

i2s_config_t i2s_config = {

.mode = (i2s_mode_t)(I2S_MODE_MASTER | I2S_MODE_RX | I2S_MODE_ADC_BUILT_IN),

.sample_rate = I2S_SAMPLE_RATE, // The format of the signal using ADC_BUILT_IN

.bits_per_sample = I2S_BITS_PER_SAMPLE_16BIT, // is fixed at 12bit, stereo, MSB

.channel_format = I2S_CHANNEL_FMT_RIGHT_LEFT,

.communication_format = I2S_COMM_FORMAT_I2S_MSB,

.intr_alloc_flags = ESP_INTR_FLAG_LEVEL1,

.dma_buf_count = 4,

.dma_buf_len = 8,

.use_apll = false,

.tx_desc_auto_clear = false,

.fixed_mclk = 0

};

i2s_driver_install(I2S_NUM_0, &i2s_config, 0, NULL);

i2s_set_adc_mode(ADC_UNIT_1, ADC_INPUT);

i2s_adc_enable(I2S_NUM_0);

}

void reader(void *pvParameters) {

uint32_t read_counter = 0;

uint64_t read_sum = 0;

while(1){

size_t bytes_read = 0;

uint16_t buffer = 0;

i2s_read(I2S_NUM_0, &buffer, sizeof(buffer), &bytes_read, portMAX_DELAY);

buffer = ~buffer; // The data is inverted

//Serial.println(buffer % 0x1000);

read_sum += buffer % 0x1000; // The 4 high bits are the channel

read_counter++;

if (bytes_read != sizeof(buffer)) Serial.println("buffer empty!");

if (read_counter == I2S_SAMPLE_RATE) {

Serial.printf("avg: %d\n", read_sum/I2S_SAMPLE_RATE);

read_counter = 0;

read_sum = 0;

i2s_adc_disable(I2S_NUM_0);

delay(READ_DELAY);

i2s_adc_enable(I2S_NUM_0);

}

}

}

void setup() {

Serial.begin(115200);

// Put a signal out on pin

uint32_t freq = ledcSetup(0, I2S_SAMPLE_RATE, 10);

Serial.printf("Output frequency: %d\n", freq);

ledcWrite(0, OUTPUT_VALUE/4);

ledcAttachPin(OUTPUT_PIN, 0);

// Initialize the I2S peripheral

i2sInit();

// Create a task that will read the data

xTaskCreatePinnedToCore(reader, "ADC_reader", 2048, NULL, 1, NULL, 1);

}

void loop() {}