Auger weigh feeder for beginners

/* MCP 3424 version 1.2 example sketch Multichannel
  Written by B@tto
  Contact : batto@hotmail.fr

  In this example, the four channel are measured and results displayed by serail connection.
*/

#include <MCP3424.h>
#include <Wire.h>
#include <Servo.h>

Servo myservo;  // create servo object to control a servo
// twelve servo objects can be created on most boards
MCP3424 MCP(6); // Declaration of MCP3424 pin addr1 et addr0 are connected to +5V

int pos = 80;    // variable to store the servo position
int sensorPin = A0;    // select the input pin for the potentiometer
long Voltage[4]; // Array used to store results
int reading;
long average;
float dispval;
bool start = 0;
const int buttonPin = 2;         // the number of the pushbutton pin
int buttonState = 0;         // variable for reading the pushbutton status

void setup() {
  myservo.attach(9);  // attaches the servo on pin 9 to the servo object
  Serial.begin(9600);  // start serial for output
  myservo.write(pos);
  pinMode(buttonPin, INPUT);
}

void loop() {

  // read the state of the pushbutton value:
  buttonState = digitalRead(buttonPin);

  if (buttonState == HIGH) {
    // turn start bit on:
   start = HIGH;
  }

  for (int a = 1; a <= 25; a++) {
    average = average + reading;
    if (a = 25) {
      dispval = average;
      average = 0;
    }
  }

  if (start == HIGH) {
    pos = 70;
    myservo.write(pos);
  }

  if (dispval > 50) {
    pos = 80;
    myservo.write(pos);
    start = LOW;
  }

  for (int i = 1; i <= 1; i++) {

    MCP.Configuration(i, 18, 1, 8); // MCP3424 is configured to channel i with 18 bits resolution, continous mode and gain defined to 8

    Voltage[i] = MCP.Measure(); // Measure is stocked in array Voltage, note that the library will wait for a completed conversion that takes around 200 ms@18bits
    reading = (Voltage[i]);
 //   Serial.print("Channel "); // print results
 //   Serial.print(i);
 //   Serial.print(" : ");
    Serial.print(((dispval + 0.0) * 1.0));
    Serial.println(" Grams");

    delay(100);
  }
}