Arduino based power supply.

Hi. I'm trying to build an Arduino nano based power supply with current limit and voltage control.
In order to do so I want to use a computer power supply to give me 12 volts that I then (using a boost converter) boost to 30v and then using a buck converter step back down to what I want.
The problem is I want to control the buck converters output voltage with the Arduino nano with a high resolution. I already know how to use the registers to get 10 bit pwm but the problem lies in the circuit going to the buck converters feedback.