Resistor Duplicator

/*
This code used to control the digital 
 potentiometer MCP42100 connected to arduino board
 
 SCLK >>D13   
 DI >>> D11 
 CS >>> D10   chip IC2 
 SHDN >>D9
 RS >>> D8
 CS >>> D7   chip IC3
 input >>> A0
 output >>> A1
 SDA >>> A4
 SCL >>> A5
 
 */


#include <Wire.h>
#include <LiquidCrystal_I2C.h>
#include <SPI.h>
byte addressPot0 = 0b00010001; // last two bits 01 is Pot 0
byte addressPot1 = 0b00010010; // last two bits 10 is Pot 1
byte addressPot0and1 = 0b00010011; // last two bits 11 is Pot 0 and 1
byte CS1 = 10; //first chip select  
byte CS2 = 7;  //second chip select
byte SHDN = 9; //chip shutdown is pin 9 use 4700 ohm for pulldown
byte RS = 8;  //chip reset is pin 8 use 4700 ohm for pulldown
byte thermister = 0;  //thermister input on A0
byte reference = 1;  //second pot input for lcd

float PotRatio = 390.625; //100000/256
float Vout=0;
float Vin=1024;
float R1=9860;  //measured resistance value for input R3
float R2=9830;  //measured resistance value for output R4
float out1=0;
float out2=0;
int out3=0;
int out4=0;
float Voutb=0;
float out1b=0;
float out2b=0;
int out3b=0;
LiquidCrystal_I2C lcd(0x3F,16,2);  // for 16 x 2 

void setup()
{
  pinMode (CS1,OUTPUT);  //when high chip reads data
  pinMode (CS2,OUTPUT);  //when high chip reads data
  pinMode (SHDN, OUTPUT);  //when high chip reads data
  pinMode (RS,OUTPUT);  //when high chip reads data
  pinMode (thermister, INPUT);
  pinMode (reference, INPUT);
  digitalWrite (SHDN, HIGH);  //power up chip (high)
  digitalWrite (RS, HIGH);  //power on reset (low)

  SPI.begin();

  digitalPotWrite(245, addressPot0and1);
  digitalWrite(SHDN, LOW);  //power off
  digitalWrite(SHDN,HIGH);  //power on
  digitalPotWrite(245, addressPot0and1);
  digitalWrite(RS,LOW); //power on reset
  delay(100);
  digitalWrite(RS, HIGH);  //power reset
  delay (2000);

  lcd.init(); 

  lcd.backlight();
  lcd.setCursor(0,0);
  lcd.print("INPUT");
  lcd.setCursor(0,1);
  lcd.print("OUTPUT");
}

void loop()
{
  //PotHighAndLow_mt(addressPot0);  // change values on pot 0
  //PotHighAndLow_mt(addressPot1);  // change values on pot 1
  PotHighAndLow_mt(addressPot0and1);  // change values on both pots
}

void PotHighAndLow_mt(byte address)
{
  Vout=analogRead(0);
  out1=(Vout/((Vin-Vout)/R1));
  out2=out1/PotRatio;
  out3=round(out2);
  out4=round(out1);
  digitalPotWrite(out3, address);
  delay(10);
  Voutb=analogRead(1);
  out1b=(Voutb/((Vin-Voutb)/R2));
}

int digitalPotWrite(byte value, byte address)
{
  digitalWrite(CS1, LOW);  //set chip IC2 active
  lcd.setCursor(7,0);
  lcd.print(out1);
  lcd.setCursor(7,1);
  lcd.print(out1b);
  SPI.transfer(address);
  SPI.transfer(value);
  delay(10);
  digitalWrite(CS1, HIGH);  //set chip IC2 inactive
  digitalWrite(CS2, LOW);  // set chip IC3 active
  SPI.transfer(address);
  SPI.transfer(value);
  delay(10);
  digitalWrite(CS2, HIGH);  //set chip IC3 inactive
}