To be done
The devices to be used are (from Robot Shop, www.RobotShop.com):
RB-Pol-207 Step up/Step downVoltage Regulator S 7V 7F5 $4.95 USD
RB-Pol-292 DRV8835 Dual Motor Driver Kit for Raspberry Pi B+ $6.99 USD
Click here to see the details about Speed and Power Indication and Control.