I have weird problem. I'm triggering a stepper motor via DRV8825 driver chip on a breadboard. Everything runs swimmingly, electricity is provided by a 12V, 2.4A DC adapter connected to VIN/GND on the Arduino. If the program is running and I disconnect the USB, everything still runs as planned.
However, if I start up the Arduino without the USB connected, the motor just makes sad little noises as if not getting enough current, maybe. Plugging the USB in For just a moment starts the program and everything works fine.
Is this a known issue? Do I have to tell the Arduino where to get its current?
Thanks for your thoughts,