Graph smoothed and converted sensor value

gistfile1.ino

/* reads a sensor on pin A0 and sends raw and smoothed values via serial, comma-separated.
   Sends COMMA-SEPARATED values in the range 0 to 1023, followed by a newline, or newline and carriage return.
   Use with "graphMultiple" processing code
   
   Created April 2011 by Eric Forman
   Updated March 21 2013 by Eric Forman
*/

const int PinA = A0;    

int A, B, C;              // values to send over serial port

// # of past samples to average by, higher = smoother but less responsive
int smoothSamples = 10;       // normal = 10          
int smoothedVal = 0;


void setup() {
  Serial.begin(9600);
}


void loop() {
  // in this example we read only one sensor and send:
  //    the actual value, the smoothed value, and the value converted to millimeters
  A = analogRead(PinA);
  B = smooth(A);
  C = getSharp2Y0A21(A);
  
  Serial.print(A);
  Serial.print(",");
  Serial.print(B);
  Serial.print(",");
  Serial.print(C);
  Serial.println();
}


int smooth(int newVal) {
  smoothedVal = smoothedVal + ((newVal - smoothedVal) / smoothSamples);
  return smoothedVal;
}


unsigned int getSharp2Y0A21(int rawVal) {
  // read Sharp 2Y0A21 sensor on analog pin "pin"
  // Sharp IR Sensor: GP2Y0A02YK, marked 2Y0A21 on the unit
  // convert voltage to distance in millimeters, still NON-LINEAR
  
  int dist_mm = 0;
  int voltage_mv = rawVal / 1023.0 * 5000; // 0 = 0v, 1023 = 5v

  // simple but processor-intensive method:
  dist_mm = 1085534.81 * (float)pow((float)voltage_mv, -1.2);

/*
  // complex but processor-efficient method:
  dist_mm = dist_mm / 4.;
  for(int i=0; i<=25; i++) {
    dist_mm = (4*dist_mm + voltage_mv/(dist_mm^4)) / 5.;
  }
  dist_mm = 1085534.81 * 1. / (voltage_mv*dist_mm);
*/
  // keep result within limits of this particular sensor 
  constrain(dist_mm, 40, 800);
  
  return dist_mm;
}