Abstract: A digital system for providing pulses that represent the position of an engine crankshaft that has a digital filter for filtering out pulses caused by noise. A square wave signal having voltage pulses that represent crankshaft position is applied to the input of the filter. The filter determines whether or not the high and low time periods of the square wave signal exceed a predetermined time period and based on this determination ignores or passes pulses of the square wave to the output of the filter.

Abstract: An ignition system for a distributorless internal combustion engine ignition system. Parameters related to the energization of a given ignition coil are stored and later utilized to control the dwell time for this same ignition coil. Another coil is energized and deenergized between the storing of parameters and the subsequent use of the parameters that relate to the given coil. The system causes a spark plug to be fired when a calculated spark timing signal is developed or at a time delayed from the occurrence of the calculated spark timing signal. Delayed spark plug firing occurs when certain conditions are not met prior to the time the calculated spark timing signal occurs. One of these conditions is that primary winding current has not attained a current limit value prior to the time that the calculated spark timing signal occurs.

Abstract: An ignition system for a distributorless internal combustion engine ignition system. Parameters related to the energization of a given ignition coil are stored and later utilized to control the dwell time for this same ignition coil. Another coil is energized and deenergized between the storing of parameters and the subsequent use of the parameters that relate to the given coil. The system causes a spark plug to be fired when a calculated spark timing signal is developed or at a time delayed from the occurrence of the calculated spark timing signal. Delayed spark plug firing occurs when certain conditions are not met prior to the time the calculated spark timing signal occurs. One of these conditions is that primary winding current has not attained a current limit value prior to the time that the calculated spark timing signal occurs.

Abstract: Included in an internal combustion engine electronic ignition system of the type having discrete circuits responsive to each selected half cycle of a series of engine synchronized alternating current timing signals for effecting engine speed ignition spark advance adjustment and for producing a series of substantially square wave electrical signals having trailing edges substantially coincident with the point of zero crossover of each selected half cycle into the next half cycle is circuitry responsive to the square wave electrical signals for inhibiting engine speed ignition spark advance adjustment with engine speeds less than a selected value.