hi everyone, i'm Michele from Italy.
i've got a strange problem:
i'm using Adafruit L293D shield motor with arduino uno to drive a double coil stepper motor.
the motor run correctly and it seems all right with my code but, if i disconnect my usb cable from pc after transferring code, the motor stop running and start to vibrate, if i reconnect usb cable to arduino and pc, all return to run correctly.
can some one explain me the reason?