void pwm(int a){
  int b = 20000-a;
  Serial.print("\nMOTOR:");
  Serial.print(a);
  Serial.print(",");
  Serial.print(b);
  Serial.print("\n");
  for (int i = 0; i < 30; i++){
    digitalWrite(3,HIGH);
    delayMicroseconds(a);
    digitalWrite(3,LOW);
    delayMicroseconds(b);
  }
}
void setup() {
  pinMode(3,OUTPUT);
  Serial.begin(9600);
  while (!Serial){}
  pwm(350);  // minimum on MG995 servo
  delay(2000);
  pwm(2600); // maximum on MG995 servo
}

void loop() {
}