# define FREQ_PRINT 10

const int pinLed = 12;  // The digital pin to which a led is connected.

unsigned long previousMicros;
unsigned long interval;
int outputState;
int l_time=0;


const int pwmMinimumWidth = 10000;  // minimum pulse width in microseconds

int pwmValue = 10;  

void setup() {
  // put your setup code here, to run once:
  Serial.begin(115200);
  Serial.setTimeout( 10);
  Serial.println( "Enter brightness, 0...100");
  
  pinMode( pinLed, OUTPUT);
}

void loop() {
  unsigned long currentMicros = micros();

    if( Serial.available() > 0)
  {
      int brightness = Serial.parseInt();    // get the number
      Serial.read(); //Delete the new line char passed after pressing enter
      pwmValue = constrain( brightness, 0, 100);  // set the new PWM value
  }


  if( currentMicros - previousMicros >= interval)
  {
    previousMicros = currentMicros;
    
    if( outputState == LOW && pwmValue != 0)
    {
      digitalWrite( pinLed, HIGH);
      outputState = HIGH;
      interval = pwmMinimumWidth * pwmValue;  // the time that the signal will be HIGH.
    }
    else if( outputState == HIGH && pwmValue != 100)
    {
      digitalWrite( pinLed, LOW);
      outputState = LOW;
      interval = pwmMinimumWidth * (100 - pwmValue); // the time that the signal will be LOW.
    }
  }

  l_time++;
  if (l_time >= FREQ_PRINT){
  Serial.print( outputState );
  Serial.print("\r\n");
  l_time=0;
  }

}