Here's a demonstration on my Teensy/Arduino project, The AutoBass.
This is a heavily modified Studiologic MP-113 Midi floor controller, using a Teensy 3.2 microcontroller. It's easy to select a key and mode, and have a chord drone on while a drum machine, electronic drum kit, or an acoustic drum kit with a trigger drive the root bass note.
Zynthian is ideal for this controller, as the sound library is immense, and it's quite easy to select and route Midi channels in custom setups.
I had a Brownsville acoustic 4-string bass converted to an 8 string. Deep enough in tone to fulfill the duties of a traditional bass, and with the octave strings it's stroing enough to stand on it's own as a rhythm instrument.