Arduino Capacitance Meter

//Arduino Capacitance Meter Code
//Measuring Range: from 100pF to 1µF
//A1 is the positive probe
//For testing the capacitors connect to A1 and GND
#define analogPin 1          //common point for connecting the resistors and positive probe
#define chargePin 2          //connect to the end of resistor of 10MΩ
#define dischargePin 3       //connect to the end of resistor of 220Ω
#define R_Value 10000000.0F  //resistor of 10MΩ

#include <LiquidCrystal.h>
LiquidCrystal lcd(8, 9, 4, 5, 6, 7);
unsigned long startTime;
unsigned long elapsedTime;
float microFarads;
float nanoFarads;
float picoFarads;

void setup() {
}
  void loop() {
  pinMode(chargePin, OUTPUT);
  digitalWrite(chargePin, LOW);
  lcd.begin(16, 2);
  digitalWrite(chargePin, HIGH);
  startTime = millis();
  while(analogRead(A1) < 648){
  }
  elapsedTime= millis() - startTime;
  microFarads = ((float)elapsedTime / R_Value) * 1000;
  lcd.print(elapsedTime);
  lcd.print(" mS");
  delay(2000);
  lcd.clear();
  delay(500);

  if (microFarads > 1){
    lcd.print(microFarads);
    lcd.print(" uF");
    delay(2000);
    lcd.clear();
    delay(500);
  }
   if (nanoFarads = microFarads * 1000.0){
    lcd.print(nanoFarads);
    lcd.print(" nF");
    delay(2000);
    lcd.clear();
    delay(500);
  }
   if (picoFarads = nanoFarads * 1000.0){
    lcd.print(picoFarads);
    lcd.print(" pF");
    delay(2000);
    lcd.clear();
    delay(500);
  }

  lcd.clear();
  digitalWrite(chargePin, LOW);
  pinMode(dischargePin, OUTPUT);
  digitalWrite(dischargePin, LOW);
  while(analogRead(A1) > 0){
  }
  pinMode(dischargePin, INPUT);
  }