#include <Arduino.h>
AudioInfo to_info(48000, 2, 32);
void setup() {
 Serial.begin(921600);
 Serial.setDebugOutput(true);
 Serial.print("hello!");
 Serial.printf("Flash chip size: %u bytes\n", ESP.getFlashChipSize());
 Serial.printf("Free DMA-capable heap: %d bytes\n", heap_caps_get_free_size(MALLOC_CAP_DMA));
 Serial.printf("Free total heap: %d bytes\n", ESP.getFreeHeap());
auto cfg = i2s.defaultConfig();
 cfg.copyFrom(to_info);
 cfg.pin_bck = GPIO_NUM_26;//14
 cfg.pin_ws = GPIO_NUM_25; //15
 cfg.pin_data = GPIO_NUM_22;
 cfg.use_apll = true;
 cfg.buffer_count = 6; // 16 does not work!
 cfg.buffer_size = 512;
 cfg.is_master = false;
 cfg.channels = 2;
 bool i2sinitialized= i2s.begin(cfg);
 if(!i2sinitialized){
 Serial.println("Failed to initialize I2S!");
 while (true) { }
 }
}
#include <math.h>
#define SAMPLE_RATE 48000
#define TONE_FREQ 400
#define CYCLE_SAMPLES ((SAMPLE_RATE / TONE_FREQ)) // Must be integer!
#define AMPLITUDE 10000 //up to 16k
int32_t buffer[CYCLE_SAMPLES * 2]; // Stereo: L + R
void generate_wave_buffer() {
 for (int i = 0; i < CYCLE_SAMPLES; i++) {
 double phase = (2.0f * M_PI * i) / CYCLE_SAMPLES;
 double sample_f = (sinf(phase)+1)/2;
 int32_t sample = ((int32_t)(sample_f * AMPLITUDE)) << 16; //adau compatibility hack
 buffer[2 * i] = sample; // Left
 buffer[2 * i + 1] = sample; // Right (or 0 if silence on R)
 }
}
void loop() {
 generate_wave_buffer();
 while (true) {
 size_t bytes_written = 0;
 i2s_write(I2S_NUM_0, buffer, sizeof(buffer), &bytes_written, portMAX_DELAY);
 }
}