A control assembly (400, 500, 600) for a communication device includes a housing having a light permeable portion (406, 506, 606), along with a rotary control formed of a shaft (408), a knob (508) or belt (608) each having a surface, and a light shining light through the light permeable portion onto the surface. Light sensitive motion detection circuitry (402, 502, 602) detects movement of the surface through the light permeable portion (406, 506, 606). The control can be implemented in high profile, low profile, scroll and slider bar embodiments, all providing a sealed environment to the communication device.