#include <Servo.h>
int ppin=9;
int spin=10;
int rpin=A0;
float readval;
float V0;
Servo myServo;

void setup() {
  // put your setup code here, to run once:
myServo.attach(spin);
pinMode(ppin, INPUT);
pinMode(rpin, INPUT);
Serial.begin(115200);
}

void loop() {
  // put your main code here, to run repeatedly:
readval=analogRead(rpin);
V0=(18./50.)*(readval-200);
Serial.println(V0);
myServo.write(V0);
}