% Duty cycle = (TON/(TON + TOFF)) *100
Where, TON = HIGH time of the square wave
             TOFF = LOW time of square wave

 Turn ON time/ (Turn ON time + Turn OFF time)

int pwmPin = 12; // assigns pin 12 to variable pwm
int pot = A0; // assigns analog input A0 to variable pot
int c1 = 0;   // declares variable c1
int c2 = 0;   // declares variable c2

void setup()  // setup loop
{
  pinMode(pwmPin, OUTPUT); 
  pinMode(pot, INPUT);  
}
void loop()
{
  c2= analogRead(pot); 
  c1= 1024-c2;         // subtracts c2 from 1000 ans saves the result in c1
  digitalWrite(pwmPin, HIGH); //ON
  delayMicroseconds(c1);//ON Time   
  digitalWrite(pwmPin, LOW); //OFF 
  delayMicroseconds(c2);  //OFF Time
}

 int pwmPin = 12;
int pot = A0;
int c1 = 0;  
int c2 = 0;

void setup()  {
  pinMode(pwmPin, OUTPUT); // declares pin 12 as output
  pinMode(pot, INPUT);  // declares pin A0 as input
}

void loop()
{
  c2= analogRead(pot);
  c1= 1024-c2;           
  digitalWrite(pwmPin, HIGH); // sets pin 12 HIGH
  delayMicroseconds(c1);   // waits for c1 uS (high time)
  digitalWrite(pwmPin, LOW);  // sets pin 12 LOW
  delayMicroseconds(c2);   // waits for c2 uS (low time)
}

int i=0;//initializing a integer for incrementing and decrementing duty ratio.
void setup()
{
                pinMode(3, OUTPUT);   // sets the pin3 as output
                pinMode(0, INPUT);// sets the pin0 as output
                pinMode(1, INPUT);// sets the pin1 as output
}
 
void loop()
{
                analogWrite(3, i);  // analogWrite values from 0 to 255
                if (digitalRead(0)==LOW)
                {
                                if (i<255)
                                {
                                                i++;//if pin0 is pressed and the duty ratio value is less than 255
                                                delay(30);
                                }
                }
                if (digitalRead(1)==LOW)
                {
                                if (i>0)
                                {
                                                i--;// if pin1 is pressed and the duty ratio value is greater than 0
                                                delay(30);
                                }
                }
}

 #include <Servo.h>

Servo servo;

attach()
write()
writeMicroseconds()
read()
attached()
detach()

servo.attach(pin)
servo.attach(pin, min, max)

servo.write(angle)

#include <Servo.h> 
Servo myservo;

void setup() 
{ 
  myservo.attach(9);
  myservo.write(90);  // set servo to mid-point
} 

void loop() {}

servo.writeMicroseconds(uS)

 #include <Servo.h> 
Servo myservo;

void setup() 
{ 
  myservo.attach(9);
  myservo.writeMicroseconds(1500);  // set servo to mid-point
} 

void loop() {}

servo.read()

servo.attached()

servo.detach()

#include <Servo.h>
Servo myservo; // create servo object to control a servo
int angle = 0; // variable to store the servo position
void setup()
{
myservo.attach(9); // attaches the servo on pin 10 to the servo object
}
void loop()
{
for(angle = 0; angle < 180; angle += 1) // goes from 0 degrees to 180 degrees
{ // in steps of 1 degree
myservo.write(angle); // tell servo to go to position in variable 'angle'
delay(20); // waits 20ms between servo commands
}

for(angle = 180; angle >= 1; angle -= 1) // goes from 180 degrees to 0 degrees
{
myservo.write(angle); // tell servo to go to position in variable ' angle '
delay(20); // waits 20ms between servo commands
}
}

myservo.attach(9,1000,2000 ); // use pin 9, set min to 1000us, max to 2000us

#include <Servo.h>
Servo myservo; // create servo object to control a servo
int potpin = 0; // analog pin used to connect the potentiometer
int val; // variable to read the value from the analog pin
void setup()
{
myservo.attach(9); // attaches the servo on pin 9 to the servo object
}
void loop()
{
val = analogRead(potpin); // reads the value of the potentiometer
val = map(val, 0, 1023, 0, 179); // scale it to use it with the servo
myservo.write(val); // sets position to the scaled value
delay(15); // waits for the servo to get there
}

#include <Servo.h>
Servo servo;
servo.attach(servo_signal_pin_attached_to);
servo.write(needed_position_ angle);

 
int i=0;//initializing a integer for incrementing and decrementing duty ratio.
#include <Servo.h>// header file for controlling servo
Servo servo;//defining the name usage as servo itself

void setup()
{
 pinMode(3, OUTPUT);   // sets the pin3 as output
 pinMode(0, INPUT);// sets the pin0 as input
 pinMode(1, INPUT);// sets the pin1 as input

servo.attach(3);
}
 
void loop()
{
 servo.write(i);//set servo potion ‘i’ degrees
               
 if (digitalRead(0)==LOW)
  {
      if (i<180)
        {
          i++;//if pin0 is pressed and degrees is less than 180
          delay(30);
         }
    }
 if (digitalRead(1)==LOW)
   {
     if (i>0)
      {
        i--;// if pin1 is pressed and degrees is greater than 0
        delay(30);
       }
    }
}