The Arduino Uno does not have true analog output (it has PWM which is "fake" analog output) but it's actually very simple to create analog output from digital outputs on N bits thanks to a DAC (Digital to Analog Converter). Making one is actually very simple using only resistors, connected in a clever way called a resistor ladder (see "https://en.wikipedia.org/wiki/Resisto...").

The program I ran here tests all 256 possibles values on 8 output digital bits and measures back the output of the resistor ladder, showing that it is quite accurate in fact (which surprised me actually)

I uploaded the source code and full output result here: https://github.com/raphaelchampeimont...