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

  • US 4,920,532 A
  • Filed: 12/07/1988
  • Issued: 04/24/1990
  • Est. Priority Date: 12/07/1988
  • Status: Expired due to Term
First Claim
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1. 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 for transmitting in a second direction, a series of current signals used for indicating the ON or OFF status of the plurality of elements;

    (b) a plurality of smart single controllers disposed throughout the motor vehicle, each one of said single controllers being disposed near one of the elements for commanding the element ON or OFF, each one of said single 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 signal;

    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 bit and a second amplitude pulse represents HIGH bits;

    3. detection means for detecting an address code of said sawtooth-pulse waveform in order to enable said single controller to command the accompanying element when the detected address code matches a preprogrammed address of said single controller;

    4. means for detecting a data bit code from said sawtooth-pulse waveform in order to determine whether to turn ON or OFF the accompanying element;

    5. means for commanding the accompanying 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 single 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.

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