| 摘要 |
An engine control system includes a microprocessor responsive to engine operating parameters for developing control words representing a desired dwell and firing time for use in controlling engine spark timing. An engine control unit is coupled to the microprocessor and utilizes the control words in calculating the desired rise and fall of the spark timing output relative to reference pulses, indicative to engine crankshaft position. The engine control unit includes a free-running counter which serves as a time reference for determining the period of the input reference pulses and for predicting the time of rise and fall of the output. Prediction of the next rise is made when the output falls and prediction of next fall is made when the output rises. Predictions are made on the assumption of constant frequency reference pulses. Errors resulting from this assumption are corrected when a reference pulse occurs.
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