Synchronization of generators

[pito]

Hi
Maybe someone knows how to synchronize these two generators?
///////////////////////////////////////////////

#define WAVEFORM_SAMPLES 400

int f = 5000;

///////////////////////////////////////////////

#include "driver/i2s.h"
#include <driver/ledc.h>

#define SAMPLE_RATE 1000000
#define WAVEFORM_SAMPLES 400     // 5khz
int f = 5000;
//#define k  SAMPLE_RATE /f/2
//#define WAVEFORM_SAMPLES  1000000 /2
//#define WAVEFORM_SAMPLES k

uint8_t stereo_buffer[WAVEFORM_SAMPLES * 2];
uint8_t wave_data1[WAVEFORM_SAMPLES];
uint8_t wave_data2[WAVEFORM_SAMPLES];

void generateWaveforms() {
  for (int i = 0; i < WAVEFORM_SAMPLES; i++) {
    wave_data1[i] = (uint8_t)((255 * i) / WAVEFORM_SAMPLES);
    wave_data2[i] = (uint8_t)(127.5 * (1 + sin(2 * 3.14159 * i / WAVEFORM_SAMPLES)));
  }
  for (int i = 0; i < WAVEFORM_SAMPLES; i++) {
    stereo_buffer[i * 2] = wave_data1[i];      // DAC1
    stereo_buffer[i * 2 + 1] = wave_data2[i];  // DAC2
  }
}

void setup() {
  Serial.begin(115200);
  generateWaveforms();

  i2s_config_t i2s_config = {
    .mode = (i2s_mode_t)(I2S_MODE_MASTER | I2S_MODE_TX | I2S_MODE_DAC_BUILT_IN),
    .sample_rate = SAMPLE_RATE,
    .bits_per_sample = I2S_BITS_PER_SAMPLE_8BIT,
    .channel_format = I2S_CHANNEL_FMT_RIGHT_LEFT,
    .communication_format = I2S_COMM_FORMAT_I2S_MSB,
    .intr_alloc_flags = 0,
    .dma_buf_count = 8,
    .dma_buf_len = WAVEFORM_SAMPLES * 2,
    .use_apll = false,
  };

  i2s_driver_install(I2S_NUM_0, &i2s_config, 0, NULL);
  i2s_set_pin(I2S_NUM_0, NULL);
  i2s_set_dac_mode(I2S_DAC_CHANNEL_BOTH_EN);
  i2s_set_sample_rates(I2S_NUM_0, i2s_config.sample_rate);
  
 ledc_timer_config_t timerConfig = {
    .speed_mode = LEDC_LOW_SPEED_MODE,
    .duty_resolution = LEDC_TIMER_10_BIT,
    .timer_num = LEDC_TIMER_0,
    //.freq_hz = 10000,
    // .freq_hz = 5000,
    .freq_hz = f,
    .clk_cfg = LEDC_AUTO_CLK
  };
  ledc_timer_config(&timerConfig);

 
  ledc_channel_config_t channelConfig1 = {
    .gpio_num = 33, //
    .speed_mode = LEDC_LOW_SPEED_MODE,
    .channel = LEDC_CHANNEL_0, //
    .timer_sel = LEDC_TIMER_0, //
    .duty = 512,
    .hpoint = 0
  };
  ledc_channel_config(&channelConfig1);

  
  ledc_channel_config_t channelConfig2 = {
    .gpio_num = 32, //
    .speed_mode = LEDC_LOW_SPEED_MODE,
    .channel = LEDC_CHANNEL_1,
    .timer_sel = LEDC_TIMER_0,
    .duty = 512,
    .hpoint = 256
  };
  ledc_channel_config(&channelConfig2);
  

void loop() {
  size_t bytes_written;
  i2s_write(I2S_NUM_0, stereo_buffer, sizeof(stereo_buffer), &bytes_written, portMAX_DELAY);
  Serial.print( "f  = "); Serial.print( f  );
 // Serial.print( "  W  = "); Serial.print(SAMPLE_RATE /f/2 );
    Serial.print( "  W  = "); Serial.print(SAMPLE_RATE /f/2 );
  Serial.println();
}​