In Part 2 of this project I cover the Arduino software needed, calibration and comparison with professional 6½ Digit Bench Multimeter.
Below are the links for the software (which I have included detailed comments) also the component layout for the PCB:
http://www.scullcom.com/LTC2400_voltmeter_software_ver3.ino
http://www.scullcom.com/Millivolt_Meter_layout.pdf