#define LED_GPIO   19
#define PWM1_Ch    1
#define PWM1_Res   8      // In bits //gives resolution 0f 2^n = 2^8 = 256
#define PWM1_Freq  70
int prevmillis;
int currentmillis;
int PWM1_DutyCycle = 0;
 
void setup()
{
  Serial.begin(9600);
  ledcAttachPin(LED_GPIO, PWM1_Ch);
  ledcSetup(PWM1_Ch, PWM1_Freq, PWM1_Res);
}
 
void loop()
{ prevmillis = millis();
  while(PWM1_DutyCycle < 255)
  {
    ledcWrite(PWM1_Ch, PWM1_DutyCycle++);
    delay(10);
    Serial.println(PWM1_DutyCycle);
  }
  // currentmillis = millis() - prevmillis ;
  Serial.println(currentmillis);
  while(PWM1_DutyCycle > 0)
  {
    ledcWrite(PWM1_Ch, PWM1_DutyCycle--);
    delay(10);
    Serial.println(PWM1_DutyCycle);
  }
  
}
//res 64 , freq 300
// fastest speed on res = 256 , freq = 70
// slowest speed on res = 1023 , freq = 400