//https://www.i-programmer.info/programming/148-hardware/17804-programming-the-esp32-in-c-pwm-first-example.html?start=4#google_vignette
#include <driver/ledc.h>
int k;
//const int btn_inc = 16;
//const int btn_dec = 17;
const int maxFreq = 18000;
const int minFreq = 5000;
//unsigned long tim_btn_inc, tim_btn_dec;
//+++++++++++++++++++++++++++++++
// variables will change:
int freq = maxFreq;
int interval = 1; // variables will change:

void setup() {
  Serial.begin(115200);
  pinMode(32, INPUT_PULLUP);    //k++
  pinMode(33, INPUT_PULLUP);   //k--
  /*
    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,              //+++++++++++++++++++++++++++++
      .clk_cfg = LEDC_AUTO_CLK
    };
    ledc_timer_config(&timerConfig);
  */

  ledc_channel_config_t channelConfig1 = {
    .gpio_num = 12,
    .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 = 27,
    .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()
{
}

//++++++++++++
void frequencyChange()  //void somefunc()
// your variable here
{
  if (digitalRead(32) == LOW) {
    k++;
    if (k > 18000) k = 18000;
   // Serial.println(k); //for debugging purposes
  }
  if (digitalRead(33) == LOW) {
    k--;
    if (k < 5000) k = 5000;
   // Serial.println(k); //for debugging purposes
  }

  ledc_timer_config_t timerConfig = {
    .speed_mode = LEDC_LOW_SPEED_MODE,
    .duty_resolution = LEDC_TIMER_10_BIT,
    .timer_num = LEDC_TIMER_0,
    .freq_hz = k,              //+++++++++++++++++++++++++++++
    .clk_cfg = LEDC_AUTO_CLK
  };
  ledc_timer_config(&timerConfig);

  //+++++++++++++++++++++++++++++++
  Serial.print("  k3 =  ");
  Serial.println(k);
  delay( 2 );
}