I've found some 12-bit DACs. I guess they can be used as an input for the LM317 (ADJ), since it's just a voltage divider, right? Or first I can try using PWM as an input for the voltage regulator.
Personally I would go for the DAC.
The transistor design is not complicated to build (and easy to understand for a rookie like me ), and is more flexible because you don't have the minimum 1,25V that the LM317 has
Trouble might appear in the filtering part, to avoid ripple. This is something to do some research in the analog world.
Do you have beefy transistor in TO-220 or TO-3 package ?
Ripple appear the input and output. The input side, you can use a PI config. Like : cap in //- inductor in serie - cap in //
I might be running out of pins quickly!
Memory select: choose 3.3, 5, 9, 12V or anything you store afterwards
I way prefer LEDs but you may be displaying a lot of info there. Maybe a few large LEDs for the Volts/Amps and a 16x2 character LCD for everything else
No to mention time
I have a 2N3055 in stock already
As OpAmps I have some LM358N for experimenting. Still not sure if they wil work for this job.
Now I'm researching how to make an analog overcurrent protection
May be look into a "crowbar" circuit
You can change the Aref to have a better resolution of the ADC
See that for voltage sensing, only a voltage divider with two resistors is used.