According to MPEG-4’s TTS architecture, facial animation can be driven by two streams simultaneouslytext, and Facial Animation Parameters. The control circuit is interfaced with a mirror position sensor and includes a variable gain amplifier whose output depends on a desired mirror equilibrium angle and a current mirror tilt angle determined by the sensor. Further, the method includes adjusting a selected electrical state of a pin of the semiconductor device and measuring a value for a dependent electrical state of the pin responsive to the selected electrical state.