Limit sum of mix ratio to 1 unless disabled by M567 S0

src/GCodes/GCodes2.cpp

@@ -3157,8 +3157,14 @@ bool GCodes::HandleMcode(GCodeBuffer& gb, const StringRef& reply)
 			Tool* const tool = reprap.GetTool(tNumber);
 			if (tool != nullptr)
 			{
+				bool seen = false;
+				if (gb.Seen('S')) {
+					seen = true;
+					tool->SetCanExceedMixSumOf1(gb.GetIValue() == 0);
+				}
 				if (gb.Seen(extrudeLetter))
 				{
+					seen = true;
 					float eVals[MaxExtruders];
 					size_t eCount = tool->DriveCount();
 					gb.GetFloatArray(eVals, eCount, false);
@@ -3168,10 +3174,12 @@ bool GCodes::HandleMcode(GCodeBuffer& gb, const StringRef& reply)
 					}
 					else
 					{
-						tool->DefineMix(eVals);
+						if (!tool->DefineMix(eVals)) {
+							reply.printf("Setting mix ratios - sum of ratios > 1.0. Disable this check with M567 P%d S0", tNumber);
+						}
 					}
 				}
-				else
+				if (!seen)
 				{
 					reply.printf("Tool %d mix ratios:", tNumber);
 					char sep = ' ';
@@ -3180,6 +3188,7 @@ bool GCodes::HandleMcode(GCodeBuffer& gb, const StringRef& reply)
 						reply.catf("%c%.3f", sep, (double)tool->GetMix()[drive]);
 						sep = ':';
 					}
+					reply.printf(". Mix ratio sum of 1.0 can be exceeded: %s", tool->GetCanExceedMixSumOf1() ? "true" : "false");
 				}
 			}
 		}

src/Tools/Tool.cpp

@@ -117,6 +117,7 @@ Tool * Tool::freelist = nullptr;
 	t->heaterFault = false;
 	t->axisOffsetsProbed = 0;
 	t->displayColdExtrudeWarning = false;
+	t->canExceedMixSumOf1 = false;
 
 	for (size_t axis = 0; axis < MaxAxes; axis++)
 	{
@@ -357,12 +358,33 @@ bool Tool::DisplayColdExtrudeWarning()
 	return result;
 }
 
-void Tool::DefineMix(const float m[])
+bool Tool::DefineMix(const float m[])
 {
+	if (this->CheckExceedsMixSumOf1(m)) {
+		return false;
+	}
 	for(size_t drive = 0; drive < driveCount; drive++)
 	{
 		mix[drive] = m[drive];
 	}
+	return true;
+}
+
+bool Tool::CheckExceedsMixSumOf1(const float m[]) const {
+	// We don't need to check if this is true
+	if (this->canExceedMixSumOf1) {
+		return false;
+	}
+
+	float sum = 0.0;
+	// Only check for the amount of configured drives
+	for(size_t drive = 0; drive < driveCount; drive++) {
+		sum += m[drive];
+		if (sum > 1.0) {
+			return true;
+		}
+	}
+	return false;
 }
 
 // Write the tool's settings to file returning true if successful

src/Tools/Tool.h

@@ -62,7 +62,9 @@ class Tool
 	int Heater(size_t heaterNumber) const;
 	const char *GetName() const;
 	int Number() const;
-	void DefineMix(const float m[]);
+	bool DefineMix(const float m[]);
+	void SetCanExceedMixSumOf1(const bool m) { canExceedMixSumOf1 = m; }
+	bool GetCanExceedMixSumOf1() const { return canExceedMixSumOf1; }
 	const float* GetMix() const;
 	float MaxFeedrate() const;
 	void Print(const StringRef& reply) const;
@@ -103,11 +105,14 @@ class Tool
 	void ResetTemperatureFault(int8_t wasDudHeater);
 	bool AllHeatersAtHighTemperature(bool forExtrusion) const;
 
+	bool CheckExceedsMixSumOf1(const float m[]) const;
+
 	Tool* next;
 	Filament *filament;
 	const char *name;
 	float offset[MaxAxes];
 	float mix[MaxExtrudersPerTool];
+	bool canExceedMixSumOf1;
 	float activeTemperatures[MaxHeatersPerTool];
 	float standbyTemperatures[MaxHeatersPerTool];
 	uint8_t driveCount;