Gm Global Technolgoy Operations, Inc.

Delco Electronics Corporation

Charles M Grimm

Robert Charles Simon, Jr

Daniel J Richardson

Kirk A Bailey

Dennis D Thompson

Dale W Deutscher

A digital spark timing control for an ignition system of a spark ignited internal combustion engine. Engine crankshaft position sensor, develops by way of example, three reference pulses and eighteen position pulses for each complete revolution of the crankshaft. The reference pulses are angularly spaced by 120.degree. and the position pulses by 20.degree.. A spark taming value is computed by a computer and its program is interrupted at the occurrence of a reference or position pulse. The system at the occurrence of each interrupt determines whether or not the spark is to occur in the next twenty degree period. If the spark should occcur in the next twenty degree period, the system utilizes the most recent twenty degree time period to determine how long it will take the engine crankshaft to rotate from its current position to the desired spark position. This compensates for spark timing errors that might otherwise occur due to changes in engine speed.

Spark timing control system

A communication method provides for an exchange of a multiple byte message between two processors. Interrupt suppression associated with the message transfer is minimized by alternating the processors between master and slave operating modes with each byte exchanged.

Interprocessor communication method

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Luxembourg, Luxembourg

Charles M Grimm