docs

firmware/controllers/core/fsio_impl.cpp

@@ -379,6 +379,8 @@ void runFsio(void) {
 
 	/**
 	 * o2 heater is off during cranking
+	 * todo: convert to FSIO?
+	 * open question if heater should be ON during cranking
 	 */
 	enginePins.o2heater.setValue(engine->rpmCalculator.isRunning());
 

firmware/controllers/trigger/rpm_calculator.cpp

@@ -128,6 +128,10 @@ void RpmCalculator::setRpmValue(int value DECLARE_ENGINE_PARAMETER_SUFFIX) {
 	} else if (rpmValue >= CONFIG(cranking.rpm)) {
 		state = RUNNING;
 	} else if (state == STOPPED) {
+		/**
+		 * We are here if RPM is above zero but we have not seen running RPM yet.
+		 * This gives us cranking hysteresis - a drop of RPM during running is still running, not cranking.
+		 */
 		state = CRANKING;
 	}
 }