opensource THC for Plasma , Fiber laser and co2 laser

// Arduino RBD Capacitance Library v1.0.5 Example - Continuously print the capacitance value.
// https://github.com/alextaujenis/RBD_Capacitance
// Copyright (c) 2015 Alex Taujenis - MIT License

#include <RBD_Capacitance.h> // https://github.com/alextaujenis/RBD_Capacitance

#include "filters.h"

const int allowed_freq = 5 * 1000 * 1000;

const unsigned long DEFAULT_MIN_FREQ =  1 * 100;
const unsigned long DEFAULT_MAX_FREQ = 30 * 10000;

const unsigned long DEFAULT_MIN_CAPA =  0;
const unsigned long DEFAULT_MAX_CAPA = 250;

unsigned long min_freq = 200000;// = 1.2 * 1000;
unsigned long max_freq = 300000;// =  12 * 1000;

unsigned long min_capa = 196;// =   1 * 1000;
unsigned long max_capa = 205;// =   4 * 1000;
const int pwmpin = 22;

RBD::Capacitance cap_sensor(13, 4); // send, receive pin

const float cutoff_freq   = 100.0;  //Cutoff frequency in Hz
const float sampling_time = 0.00005; //Sampling time in seconds.
IIR::ORDER  order  = IIR::ORDER::OD1; // Order (OD1 to OD4)

// Low-pass filter
Filter f(cutoff_freq, sampling_time, order);

int pwm_ch = 0;
int resolution = 1;

float capa_val;

float capatofreq(float capa_val) {
  float ret_val = 0;
  
  if ( capa_val < min_capa ) {
    ret_val = min_freq;

  } else if ( capa_val > max_capa ) {
    ret_val = max_freq;
  } else {
    ret_val = min_freq + (max_freq - min_freq) / ((float)(max_capa - min_capa)) * (capa_val - min_capa);
  }
  //return ret_val;
  return (float)(max_freq - (ret_val - min_freq));
}

void setup() {
  Serial.begin(115200);
  
  Serial.println("Starting...");
  
  ledcSetup(pwm_ch, min_freq, resolution);
  ledcAttachPin(pwmpin, pwm_ch);

  cap_sensor.setSampleSize(15);

}

void loop() {
  cap_sensor.update();
  if(cap_sensor.onChange()) {
      // code only runs once per event
      capa_val = cap_sensor.getValue();
      Serial.print("capa_val: ");
      Serial.println(capa_val);
      float filteredval = f.filterIn(capa_val);
      capa_val = filteredval;
      int pwm_val = (int)capatofreq(filteredval);    
       
      ledcSetup(pwm_ch, pwm_val, resolution);
      ledcWrite(pwm_ch, 1);
      
      Serial.print("filter_val: ");
      Serial.println(capa_val);
      Serial.print("capa mode pwm_val: ");
      Serial.println(pwm_val);
      
  

  }
}