Patent ID: 9541052
Date: 2017-01-10
CPC Classifications: F02D,F02P,G01M

Claim:
1. An ignition system controlled by a powertrain controller via a dwell line carrying a dwell signal, comprising: a state machine monitoring a dwell period between consecutive dwell signals and adjusting a rate of a variable clock signal according to the dwell period; a multi-bit counter clocked by the adjusted clock signal, the counter having a first set of bits used by the state machine to establish an integration period, and a second set of bits coupled to a resistive ladder generating a stair step signal having a plurality of cycles during the integration period; a current sensor providing a current signal proportional to the ion current; a comparator comparing the current signal to the stair step signal; an ion current counter incremented during the integration period whenever the current signal indicates an ion current magnitude greater than the stair step signal, wherein an accumulated count at the end of the integration period is reported to the powertrain controller as a measure of the ion current.