Gm Global Technolgoy Operations, Inc.

Itt Automotive Electrical Systems, Inc.

Donald L Mueller

Michael B Monahan

Glen A Nyberg

Benjamin L Miciano

Amanda R Wright

A power-on-reset and watchdog circuit is disclosed which employs discrete bipolar transistors to provide reset capability for microprocessors in the event of power-up or microprocessor malfunction. The present invention has a watchdog detection circuit which monitors a pulsed microprocessor output signal. As long as the watchdog detection circuit receives the pulsed microprocessor output signal, the microprocessor will not reset. In the event of microprocessor malfunction the pulsed microprocessor output signal will latch either high or low, initiating an oscillator circuit to reset the microprocessor. Upon power-up, the watchdog detection circuit will be forced into the off state for a specified amount of time so as to invoke the oscillator circuit, thereby resetting the microprocessor.

Power-on-reset and watchdog circuit and method

A vehicle window wiper interfacing arrangement for interconnecting a window wiper function switch, a wiper motor controller, and an auto-delay controller to permit a water drop sensor to control a window wiper delay time when a window wiper system is operated in an AUTO-DELAY mode. The auto-delay controller outputs three wiper function signals, namely OFF, LOW speed and WASH to the wiper motor controller via a single bi-directional multiplexed line. The wiper motor controller outputs a wiper position signal to the auto-delay controller via the same bi-directional multiplexed line for use by a control program to determine a proper wiper delay time period.

Windshield wiper auto-delay control interface

A window wiper system for an automotive vehicle provides multiplex encoding of a control switch signal and an additional wiper control signal in a two-channel multiplex control signal and decoding of the multiplex control signal by the wiper mechanism for control of wiper operation. The multiplex control signal is a cyclical waveform containing alternating cycles of different first and second periods wherein the duty cycle of the first period cycles is determined by the additional wiper control signal and the duty cycle of the second period cycles is determined by the control switch. The additional wiper control signal may be derived from a rain sensor, an intermittent delay control resistor or any other device on the passenger side of the vehicle firewall which generates a signal controlling wiper operation.

Multiplexed vehicle window wiper control

A washer fluid monitor comprising a pair of electrically conducting probes projecting downward into a washer fluid reservoir and incorporated into part of the positive feedback loop of a Wien bridge oscillator. One of the probes is grounded; and the Wien bridge oscillator is modified with an additional capacitor isolating the other probe from the DC supply and intermediate voltages so that it is essentially grounded at the oscillator frequency to greatly reduce or eliminate ionic currents in the washer fluid and resulting probe degradation without the need for an isolating transformer.

Washer fluid monitor

A pair of outer conducting members on the outside of a windshield are separated by a long common insulating border defining a border resistance in parallel with a first capacitance. Each of the outer conducting members is capacitively coupled through a layer of the windshield to an inner conducting member to form coupling capacitances in series with the combination of the border resistance and first capacitance. The preceding elements form a timing circuit for an oscillator, the timing circuit having an equivalent capacitance varying with the border resistance. When water droplets bridge the border of the outer conducting members, the border resistance decreases from infinity to change the equivalent capacitance of the timing circuit and thus the frequency of the oscillator circuit; and this change is detected to modify wiper operation.

Growing community of inventors

Dayton, OH, United States of America

Donald L Mueller