Documents:
Schematic and Description
Arduino Source Code (Version 2a)
I expanded Paul Badger's original example code to implement auto ranging and some other mentioned ideas. My prototype box can measure capacitors just above 1nF into the milli-Farad range. I originally wrote this code to test and match large capacitors (especially salvaged ones). My meter's range only goes up to 20uF, so I needed something better. Accuracy is about 3% with ESR playing the biggest part in that. The unit will measure the capacitor with 2 different resistors and print a difference percent that hints at ESR. 1% or less seems to indicate a low ESR capacitor.