A controller can be used to drive a stepper motor or a muscle wire. A bipolar stepper motor can use the same hardware a block speed controller with a simple motor stepping logic replacing the PWM module. Fine control of a muscle wire can be achieved by increasing and decreasing the power at a controlled rate. This can be done using PWM similar to a block speed controller except that this will be unidirectional. The H bridge driver may be replaced by a simple transistor driver.
A hand held controller consisting of buttons, potentiometers or LEDs can be used. This will plug into the bus directly. Potentiometers can be read by connected them to a 555 and measuring the output pulse width. With the bus topology wiring, the hand held controllers will have walk-around capability.
An infra red or UHF receiver could be interfaced to a controller allowing a cordless unit to control the layout.
A sound unit could be switched to a series of speakers around the layout by a controller.
