Abstract: A method is disclosed that includes receiving a classification voltage at a powered device from a network. The classification voltage includes a baseline voltage level that is below an operating voltage range of the powered device and includes a sequence of distinct signal elements derived from the classification voltage. The method further includes detecting a number of signal elements of the sequence of distinct signal elements. A current is drawn until the number of signal elements exceeds a predetermined number.

Abstract: A method for calibrating an optical reflectance proximity sensor and then measuring proximity in a repeating cycle or on demand, the sensor including one or more wavelength transmitting diodes, one or more wavelength receiving diodes, an ambient correction circuit, and a comparator circuit, and further teaching steps for powering on the sensor, canceling the ambient signal during a calibration period, transmitting wavelengths to and receiving reflectance from an object in the path of the transmitted wavelengths, and measuring a reflectance pulse width and comparing the value to a preset value to determine proximity.