fix instant rpm clearing bug (#4629)

* improve instant rpm

* changelog

firmware/CHANGELOG.md

@@ -29,6 +29,9 @@ Release template (copy/paste this for new release):
 ### Added
  - Flexible ignition adder/trim tables #4586
 
+### Fixed
+ - Slower than expected RPM information was slowing engine start #4629
+
 ## September 2022 Release - "Day 203"
 
 ### Added

firmware/controllers/engine_cycle/rpm_calculator.cpp

@@ -209,11 +209,9 @@ uint32_t RpmCalculator::getRevolutionCounterM(void) const {
 }
 
 void RpmCalculator::onSlowCallback() {
-	/**
+	// Stop the engine if it's been too long since we got a trigger event
-	 * Update engine RPM state if needed (check timeouts).
+	if (!engine->triggerCentral.engineMovedRecently(getTimeNowNt())) {
-	 */
+		setStopSpinning();
-	if (!checkIfSpinning(getTimeNowNt())) {
-		engine->rpmCalculator.setStopSpinning();
 	}
 }
 

firmware/controllers/trigger/decoders/trigger_structure.h

@@ -294,5 +294,3 @@ void findTriggerPosition(
 void setToothedWheelConfiguration(TriggerWaveform *s, int total, int skipped, operation_mode_e operationMode);
 
 #define TRIGGER_WAVEFORM(x) getTriggerCentral()->triggerShape.x
-
-#define getTriggerSize() TRIGGER_WAVEFORM(wave.phaseCount)

firmware/controllers/trigger/trigger_decoder.cpp

@@ -280,6 +280,8 @@ float PrimaryTriggerDecoder::calculateInstantRpm(
 	// now let's get precise angle for that event
 	angle_t prevIndexAngle = triggerFormDetails->eventAngles[prevIndex];
 	efitick_t time90ago = timeOfLastEvent[prevIndex];
+
+	// No previous timestamp, instant RPM isn't ready yet
 	if (time90ago == 0) {
 		return prevInstantRpmValue;
 	}
@@ -293,9 +295,10 @@ float PrimaryTriggerDecoder::calculateInstantRpm(
 	// Wrap the angle in to the correct range (ie, could be -630 when we want +90)
 	fixAngle(angleDiff, "angleDiff", CUSTOM_ERR_6561);
 
-	// just for safety
+	// just for safety, avoid divide-by-0
-	if (time == 0)
+	if (time == 0) {
 		return prevInstantRpmValue;
+	}
 
 	float instantRpm = (60000000.0 / 360 * US_TO_NT_MULTIPLIER) * angleDiff / time;
 	assertIsInBoundsWithResult(current_index, instantRpmValue, "instantRpmValue", 0);

unit_tests/tests/trigger/test_real_gm_24x.cpp

@@ -12,10 +12,23 @@ TEST(crankingGm24x, gmRealCrankingFromFile) {
 
 	eth.setTriggerType(TT_GM_24x);
 
+	int eventCount = 0;
+	bool gotRpm = false;
+
 	while (reader.haveMore()) {
 		reader.processLine(&eth);
+		eventCount++;
 
 		engine->rpmCalculator.onSlowCallback();
+
+		auto rpm = Sensor::getOrZero(SensorType::Rpm);
+		if (!gotRpm && rpm) {
+			gotRpm = true;
+
+			// We should get first RPM on exactly the first sync point - this means the instant RPM pre-sync event copy all worked OK
+			EXPECT_EQ(eventCount, 23);
+			EXPECT_NEAR(rpm, 77.0f, 0.1);
+		}
 	}
 
 	ASSERT_EQ( 0, eth.recentWarnings()->getCount())<< "warningCounter#vwRealCranking";