Now that I have the rotary encoders working properly, it's time to think about the motor control circuit. I have an Atmel AVR ATmega32 with three PWM outputs, of which I'll use two for motor control. I'm planning a differential drive robot, that is, one with two drive motors, one for the left side and one for the right side. I'll need forward and reverse directional control of both motors, as well as speed control via PWM. I have a couple of L298 H-bridge chips, so they'll do nicely.