tach sweep experiment

firmware/controllers/modules/tachometer/tachometer.cpp

@@ -41,7 +41,7 @@ void TachometerModule::onFastCallback() {
 	}
 
 	// What is the angle per tach output period?
-	float cycleTimeMs = 60000.0f / Sensor::getOrZero(SensorType::Rpm);
+	float cycleTimeMs = 60000.0f / getRpm();
 	float periodTimeMs = cycleTimeMs / periods;
 	tachFreq = 1000.0f / periodTimeMs;
 
@@ -62,6 +62,37 @@ void TachometerModule::onFastCallback() {
 	tachControl.setFrequency(tachFreq);
 }
 
+float TachometerModule::getRpm() {
+	float trueRpm = Sensor::getOrZero(SensorType::Rpm);
+
+	if (!m_doTachSweep) {
+		return trueRpm;
+	}
+
+	float elapsed = m_stateChangeTimer.getElapsedSeconds();
+	float sweepPosition = elapsed / engineConfiguration->tachSweepTime;
+
+	if (sweepPosition > 1) {
+		// We've done a full sweep time, we're done!
+		m_doTachSweep = false;
+		return trueRpm;
+	} else if (sweepPosition < 0.5f) {
+		// First half of the ramp, ramp up from 0 -> max
+		return interpolateClamped(0, 0.5f, 0, engineConfiguration->tachSweepMax, sweepPosition);
+	} else {
+		// Use y2 = trueRpm instead of 0 so that it ramps back down smoothly
+		// to the current RPM if the engine started during ther ramp
+		return interpolateClamped(0.5f, 1, engineConfiguration->tachSweepMax, trueRpm, sweepPosition);
+	}
+}
+
+void TachometerModule::onIgnitionStateChanged(bool ignitionOn) {
+	if (ignitionOn && engineConfiguration->tachSweepTime != 0) {
+		m_stateChangeTimer.reset();
+		m_doTachSweep = true;
+	}
+}
+
 void initTachometer() {
 	tachHasInit = false;
 

firmware/controllers/modules/tachometer/tachometer.h

@@ -9,8 +9,23 @@
 
 void initTachometer();
 
-struct TachometerModule : public EngineModule {
-
+class TachometerModule : public EngineModule {
+public:
 	// TODO: can/should this be slow callback instead?
 	void onFastCallback() override;
+	void onIgnitionStateChanged(bool ignitionOn) override;
+
+private:
+	float getRpm();
+
+	bool m_doTachSweep = false;
+
+	enum class TachState {
+		Normal,
+		RampUp,
+		RampDown,
+	};
+
+	TachState m_state = TachState::Normal;
+	Timer m_stateChangeTimer;
 };

firmware/integration/rusefi_config.txt

@@ -744,7 +744,8 @@ output_pin_e acFanPin;Optional Radiator Fan used with A/C
 
 	Gpio[EGT_CHANNEL_COUNT iterate] max31855_cs;
 	brain_input_pin_e flexSensorPin;Continental/GM flex fuel sensor, 50-150hz type;
-	uint16_t unused720
+	uint8_t autoscale tachSweepTime;Total time for the tach to sweep up then back down at startup. Set to 0 to disable sweep.;"s", 0.1, 0, 0, 10, 1
+	uint8_t autoscale tachSweepMax;Maximum RPM for the startup tach sweep.;"rpm", 50, 9, 0, 12500, 0
 	pin_output_mode_e stepperDirectionPinMode;
 
 	spi_device_e mc33972spiDevice;