// flex sensor with servo by Alexander Reeder
// Oct 1 2007

int servoPin = 2;     // Control pin for servo motor
int minPulse = 500;   // Minimum servo position
int maxPulse = 2500;  // Maximum servo position
int pulse = 0;        // Amount to pulse the servo
int modPulse = 800;
int diffPulse = 0;
int prevPulse = 0;

long lastPulse = 0;    // the time in milliseconds of the last pulse
int refreshTime = 20; // the time needed in between pulses

int analogValue = 0;  // the value returned from the analog sensor
int analogPin = 0;    // the analog pin that the sensor's on

int threshold = 20;

void setup() {
  pinMode(servoPin, OUTPUT);  // Set servo pin as an output pin
  pulse = minPulse;           // Set the motor position value to the minimum
  Serial.begin(9600);
}

void loop() {
  analogValue = analogRead(analogPin);      // read the analog input

  pulse = analogValue+200; 
  diffPulse = pulse - prevPulse;
  if (diffPulse < 0)
    diffPulse = diffPulse*-1;
  
  prevPulse = pulse;

  // pulse the servo again if rhe refresh time (20 ms) has passed:
  if (millis() - lastPulse >= refreshTime) {
    if (diffPulse > threshold) 
      pulse = analogValue+200+((pulse%8)*5);
    digitalWrite(servoPin, HIGH);   // Turn the motor on
    delayMicroseconds(pulse);       // Length of the pulse sets the motor position
    digitalWrite(servoPin, LOW);    // Turn the motor off
    lastPulse = millis();           // save the time of the last pulse
  }
}