You definitely need a tight connection for controlling a stepper/servo in real time. This is why most motion controllers are in close proximity to the actual driver (open or closed loop) electronics.

The Arduino has been used for many purposes, and “shields” are available to make many common tasks easier. However, [Nick] wanted a stackable motor driver shield, so he build one himself!. ...

no more off-board 0.1in header connections – only proper connectors; Power from the ~36V motor supply rail; Isolated USB if there has to be USB; Connection for an ‘off-line controller’ (see below) if ...

Seeing this Toshiba motor drive, my first thought was ‘what a neat chip for pairing with an Arduino’ as it combines operation across 1.8 to 7V with up to 4A drive – so that is Li-ion batteries, 5V USB ...