I made a variable linear power supply 0-30V 0-10A and course I made also an amp/voltmeter with an arduino mini pro.
I show current (A, 2 decimals) and Voltage (2 decimals) on oled display SH1106 MODULE ECRAN LCD OLED pour ARDUINO 1.3 POUCES .
Current measurement is done with arduino module ACS712 30A (listen, I was to lazy to make an dedicated board with the atmega and the Oled and the sensor).
voltage measurement is done with the arduino mini pro himself
.IMHO the voltage measurement is precise enough.
Concerning current, the ACS712 is a piece of s..it, it changes the offset current when is a little hot (it has usually 120-140 mA offset, I had to ""decide" the offset current when starting the ACS module otherwise you see what gigantic errors you get...).You can avoid this...There are some professional current detectors on the market you can choose.And cherry on the cake Allegro said:"For existing customer transition, and for new customers or new applications, use ACS723."
So do you really need the voltage precision (or current)?Beside, I don't know if the ADS1115 isn't another bad surprise like the ACS712.Normally, TI make good products, so the 1115 should do fine, if you REALLY need the precision.
Anyway you have to 'calibrate' the V and I readings.
I can share the arduino sketch if you want, it works from some time (I had to deactivate the reset pin I had some resets on the mini pro... and wanted to be a little industrial performance).
Edit 1:Are you sure 0.96 isn't tooo little?See here the 1.3 oled.
Edit 2: you don't need UDN/ULN stuff, just pout some npn.
Edit 3: I don't get the 2xoled idea, why complicate the things?Then you need to do 2 windows in the case, 2 fixations, more wires.One display is not a better solution?
To be continued I hope,
Best regards, Ovidiu