Hi, I want to control a stepper motor with a driver a4988 and arduino and I ask: I can connect the ground of the ATX power supply 12V to the arduino ground? because I have heard that is very important to connect GNDs of arduino with ATX power supply and ground of a4988.
It's that true?
Thanks.
Yes it is true, without connecting the grounds together it will not work.
See this as to why:-
http://www.thebox.myzen.co.uk/Tutorial/Power_Supplies.html