#include <Servo.h>

Servo Wiper1;
Servo Wiper2;

int Activator_pin = 2;
int Wiper1_pin = 3;
int Wiper2_pin = 5;

const unsigned int restAngle = 20;  //resting position of wipers
const unsigned int maxAngle = 160;  //maximum position of wipers
unsigned int angle = restAngle;     //current position of wipers
int deltaAngle = 1;                 //change angle by this, each pass through the code; starts positive if restAngle<maxAngle, negative if opposite
bool runningFlag = false;           //start off at rest
int speed = 2;                      //increase to slow the wipers, decrease to speed them up

void setup() {
  pinMode(Activator_pin, INPUT_PULLUP);  //wired pin to button to GND, means input will be low when button pressed
  Wiper1.write(restAngle);  //Write BEFORE attach, to set initial angle appropriately
  Wiper2.write(restAngle);
  Wiper1.attach(Wiper1_pin);
  Wiper2.attach(Wiper2_pin);
}

void loop() {
  if (digitalRead(Activator_pin) == 0) runningFlag = true;                     //inverted due to low-active button
  else if (angle <= restAngle) runningFlag = false;                            //we only turn off the wiper at minimum
  if (runningFlag) {
    angle = angle + deltaAngle;
    if (angle >= maxAngle || angle <= restAngle) deltaAngle = deltaAngle * -1; //turn around at endpoints
    Wiper1.write(angle);
    Wiper2.write(angle);
    delay(speed);                                                              //speed constant could be modified, for example a high/low selector
  }
}