implement DFCO hysteresis #478

firmware/controllers/algo/fuel/dfco.cpp

@@ -20,7 +20,8 @@ bool DfcoController::getState() const {
 	}
 
 	// MAP sensor is optional, only inhibit if the sensor is present but broken
-	if (Sensor::hasSensor(SensorType::Map) && !map) {
+	bool hasMap = Sensor::hasSensor(SensorType::Map);
+	if (hasMap && !map) {
 		return false;
 	}
 
@@ -31,7 +32,7 @@ bool DfcoController::getState() const {
 		interpolate2d(rpm, config->dfcoMapRpmValuesBins, config->dfcoMapRpmValues) :
 		engineConfiguration->coastingFuelCutMap;
 
-	bool mapActivate = map.value_or(0) < mapThreshold;
+	bool mapActivate = !hasMap || !m_mapHysteresis.test(map.value_or(0), mapThreshold + 1, mapThreshold - 1);
 	bool tpsActivate = tps.Value < engineConfiguration->coastingFuelCutTps;
 	bool cltActivate = clt.Value > engineConfiguration->coastingFuelCutClt;
 	// True if throttle, MAP, and CLT are all acceptable for DFCO to occur

firmware/controllers/algo/fuel/dfco.h

@@ -5,6 +5,7 @@
 #pragma once
 #include "engine_module.h"
 #include "timer.h"
+#include "limp_manager.h"
 
 // DFCO = deceleration fuel cut off, ie, save gas when your foot is off the pedal
 class DfcoController : public EngineModule {
@@ -19,6 +20,8 @@ class DfcoController : public EngineModule {
 	bool getState() const;
 	bool m_isDfco = false;
 
+	mutable Hysteresis m_mapHysteresis;
+
 	Timer m_timeSinceCut;
 	Timer m_timeSinceNoCut;
 };

unit_tests/tests/ignition_injection/test_fuelCut.cpp

@@ -243,12 +243,12 @@ TEST(fuelCut, mapTable) {
 	EXPECT_NORMAL();
 
 	// Drop MAP to just above the interpolated cutoff curve
-	Sensor::setMockValue(SensorType::Map, 41);
+	Sensor::setMockValue(SensorType::Map, 43);
 	eth.engine.periodicFastCallback();
 	EXPECT_NORMAL();
 
 	// Drop MAP to just below the interpolated cutoff curve
-	Sensor::setMockValue(SensorType::Map, 39);
+	Sensor::setMockValue(SensorType::Map, 37);
 	eth.engine.periodicFastCallback();
 	EXPECT_CUT();