Electrical devices command system, single wire bus and smart dual controller arrangement therefor

A multiplex system within a motor vehicle for commanding and monitoring the status of a plurality of electrical devices or elements disposed throughout the motor vehicle, each of the elements having command terminals for receiving commands in the form of a discrete voltage signal for activating or deactivating each of the elements, one of the command terminals also being used to provide a status indication of each of the elements in the form of a current signal upon being commanded, said system comprising:

• (a) a bi-directional, single wire bus for transmitting in a first direction a series of square wave, double duty cycle, voltage signals used for commanding ON or OFF the plurality of elements and a series of current signals transmitted in a second direction used for indicating the ON and OFF status of the plurality of elements;
• (b) a plurality of smart dual controllers disposed throughout the motor vehicle, each one of said dual controllers being disposed near a pair of elements for commanding ON or OFF one of the pair of elements, each of said dual controllers having:
• (1) a single input/output terminal connected by a single wire to a single point along said bus for receiving the square-wave voltage signals from said bus and;
• (2) integration means for converting the square-wave voltage signal into a dual-amplitude, sawtooth-pulse waveform containing address and data information wherein a first amplitude pulse represents LOW bits and a second amplitude pulse represents HIGH bits;
• (3) detection means for detecting a first portion of an address code from said sawtooth-pulse waveform in order to enable said dual controller to command one of the pair of elements when the detected address code matches a preprogrammed address of said dual controller, said detection means also including means for detecting a second portion of the address code used for selecting which one of the pair elements to command ON or OFF;
• (4) means for detecting a data bit code from said sawtooth pulse waveform in order to determine whether to turn ON or OFF the selected element;
• (5) means for commanding the selected element ON or OFF, said commanding means including means for transmitting a current signal back over said bus indicative of the status of the element after commanding the element ON or OFF;
• (c) a driver and receiver means, receiving power from a power source of the vehicle and connected to said single-wire bus, for generating the series of square-wave, double-duty cycle voltage signals used by each of said dual controllers, said driver and receiver means also including means for receiving the status of the elements indicating current signals transmitted over said bus;
• (d) display means for displaying the status of the plurality of elements;
• and
• (e) a microcomputer means interconnecting said driver and receiver means and said display means for (1) writing logic commands to said driver and receiver means for controlling the generating of the series of square-wave, double-duty cycle voltage signals used for placing address and command information on said bus, (2) reading the current signals indicative of the status of the commanded element;
• (3) establishing a history of performance of each of the commanded elements;
• and (4) transferring updated status information to said display means.