Abstract: A two-way handshake circuit and method for communications between digital devices, such as microprocessors which employs one tri-state input/output port pin per microprocessoror digital device. The configuration of each tri-state input/output port pin is controlled by control software within the digital device. The tri-state input/output port pins are connected by a self-latching circuit employing two parallel branches. A first branch includes a first amplifier or inverter connected in series with a first resistor so as to allow voltage level changes to be reflected in only one direction. A second branch includes a second amplifier or inverter connected in series with a second resistor so as to allow voltage level changes to be reflected in the opposite direction of the first branch.

Abstract: A method for detecting full or partial inoperability of a vehicular alternator battery charging system monitors the vehicle's battery voltage and compares it against a controlled reference voltage. When the monitored voltage differs from the target by an amount which is a function of engine rotational speed for a minimum preselected time period, the alternator is disabled and the voltage drop at the battery is monitored to determined whether the alternator is malfunctioning. By observing the voltage drop when the alternator is disabled, the method can distinguish between a charging system problem and a normal state wherein the load exceeds the alternator's maximum output current capacity.

Abstract: A method for firing a spark plug in an engine which employs a simulated high data rate signal. The simulated high data rate signal is generated by a preselected number of gaps in a flywheel within a predetermined time segment of each cylinder event time called the spark event. A sensor generates the simulated high data rate signal as the gaps rotate past it. Data pulses are generated and stored within the spark event. In the case of distributorless ignition systems, the spark plug to be fired is identified. In one embodiment, a widened gap in the flywheel is used to perform this identification. The occurrence time of the leaading and trailing edges of the data pulses are received and stored. The rate of rotation including velocity and possibly acceleration is calculated and stored upon the occurence of each pulse. The spark firing time within the spark event is calculated and stored upon the occurrence of each pulse. Finally, the spark plug is fired once within the spark event.

Abstract: A method to disengage an electronic speed control as a function of the condition of the park/neutral gear or manual clutch. If the automatic transmission lever is bumped from "drive" or the manual transmission clutch is depressed while the electronic speed control is operating, the method will sense this by detecting a difference in the ratio of engine speed to vehicle speed. If the ratio changes by .+-.25 percent, the electronic speed control is disengaged.

Abstract: A decision is made to disable the resume switch if it is found in an engage condition at the same time that normal electronic speed control cut-outs are in effect due to conditions such as: brake on, car speed too low, park/neutral gear engaged (automatic transmission), clutch engaged (manual transmission), RPM too high, or N/V (the ratio of engine speed N to vehicle speed V) is out of range.

Abstract: A system and method for the detection and correction of purge corruption in the adaptive memory portion of a control system controlling, in part, the fuel to air ratio during the cold start up of an internal combustion engine. This is achieved by performing two calibrations (or updates) of the adaptive memory cells (or locations) during the previous engine operation. The adaptive memory is first updated with the purge system off. The memory locations addressed at this time are denoted as the purge free adaptive memory cells. Next, the adaptive memory is updated with the purge system on. These memory locations are denoted as the normal adaptive memory cells. During the next cold engine start, purge corruption of the adaptive memory is detected when the difference between the two calibrations exceeds a value representing an absence of purge corruption.

Abstract: In an idle speed control system for an engine equipped with a fuel/air mixture means and an air bypass means or movable throttle stop means, the idle speed can be quickly moved to the desired value by temporarily changing the spark advance and holding the changed spark advance until the air bypass system or movable throttle stop means has had a chance to respond to the various demands of the idle condition.

Abstract: A microprocessor-based electronic voltage regulation system for controlling the charging of the battery in a vehicle. The conventional voltage regulator is eliminated and the intelligence of the microprocessor already present on the vehicle for controlling engine operation is used to regulate the output of the alternator. The battery temperature signal from a temperature transducer and a battery voltage signal from a sense line connected directly to the positive terminal of the battery are supplied to the microprocessor through an analog-to-digital converter. The microprocessor is programmed to ascertain from the battery temperature signal the desired set point voltage based upon an inverse first order relationship between battery temperature and desired battery voltage with preset maximum and minimum voltage set point levels.

Abstract: The need for an accurate measure of the throttle position exists so the electronic engine controller is employed: to continuously check the position of the throttle, to memorize the lowest throttle position reading from the throttle pot, and to define this position as closed throttle. The reading is then updated to compensate for wear in the throttle blade linkages or in the potentiometric device or due to temperature or other conditions. The electronic engine controller will read and retain the lowest measured value of the potentiometric voltage output. This value will then be stored in memory and identified as the closed throttle output until it is necessary to redefine it.

Abstract: A system and method for synchronizing ignition and fuel injection pulses produced by the interruption of Hall Effect signals by a window-in-vane interrupter in an internal combustion engine ignition distributor.