jimLee:
I take the 12V & Gnd. to both 5V supply and the motor driver.
5V & Gnd from the supply to the µprocssor. Then only the ONE digital line from the processor to the motor driver. Ground out the other driver data line. Hook up motor, done.
This sounds very clear! I will try setting up the power lines as you did but keeping the relays. If still won't work, I'll buy the motor drivers.
Thank you very much!