Electronic Load, 3V to 200V DC, max 100W.

I am currently planning to build this wide range DC elctronic load with an Uno, 1602 LCD, pwm and encoder.
I hope this project will help all those power electonics enthusiasts and professionals out there.
The hardware is already planned out, but I need help with software and all types of suggestions are anticipated.

Well what features do you already have - I'd suggest having constant resistance and constant current modes
for a start, data-logging, automatic shut-off (for battery discharge).

[ Ooh, yes, cascadable output stage, so you can pop in a second one to get 200W handling for instance? ]