#include <Wire.h >
    int servo = 0;
    int d1=0;
    int angle;
    int pwm;
    
    void setup() {
        pinMode(servo, OUTPUT);
        Serial.begin(9600);
        Wire.begin(9); // change address
        Wire.onReceive(receiveEvent);
    }
    
    void loop() {
        if (d1 == 1) {
        for (angle = 0; angle <= 140; angle += 10)  {
            servoPulse(servo, angle);  }
        for (angle = 140; angle >= 0; angle -= 10)  {
            servoPulse(servo, angle);  }
        } else {
        
        }
        delay(500);
    }
    
    void receiveEvent(int howMany) {
        while (Wire.available()) {
        d1 = Wire.read();
        }
    }
    
    void servoPulse (int servo, int angle)
    {
        pwm = (angle*11) + 500;      // Convert angle to microseconds
        digitalWrite(servo, HIGH);
        delayMicroseconds(pwm);
        digitalWrite(servo, LOW);
        delay(50);                   // Refresh cycle of servo
    }