Hi, very cool project! I love your board. I know very little about circuits, just learning. I am wondering, is your power supply starting AC? I see that you have capacitors near where the power comes in. Are those needed if your incoming power is DC? If so, can you explain the purpose? Thank you. Also, could you run that board on 12V ?  I am interested in your project because I would like to control 2 (larger) DC motors with Arduino and the DRV8844. I was planning to use a 12v battery as the power source, and also include a solar charging controller. (I would guess that I'd need diodes to block the charger from sending juice to the Arduino as well but, not sure). 

Thanks for your interest! The board was designed to run off a 12V DC computer power supply, similar to your battery system. Controlling the chip is pretty straightforward with Arduino, I don't have any code posted now but I'm sure I could dig up some of my examples which should compile in Arduino with minor changes. The capacitors are there to provide extra juice to the motor driver when the motors first start, since there will be a current spike on start-up and the voltage will dip, potentially to the point of brown-out on the chip. I highly recommend looking through the DRV8844 datasheet and the example circuit for a better explanation of which external capacitors and extra components to use with the part. Hope this helps, and good luck with your project!