Z probe trigger height is now the negative of the probe Z offset

2 files changed, 17 insertions, 11 deletions

diff --git a/src/Endstops/ZProbe.cpp b/src/Endstops/ZProbe.cpp
index 47fa542f..95853119 100644
--- a/src/Endstops/ZProbe.cpp
+++ b/src/Endstops/ZProbe.cpp
@@ -78,7 +78,7 @@ constexpr ObjectModelTableEntry ZProbe::objectModelTable[] =
 	{ "threshold",					OBJECT_MODEL_FUNC((int32_t)self->adcValue), 						ObjectModelEntryFlags::none },
 	{ "tolerance",					OBJECT_MODEL_FUNC(self->tolerance, 3), 								ObjectModelEntryFlags::none },
 	{ "travelSpeed",				OBJECT_MODEL_FUNC(self->travelSpeed, 1), 							ObjectModelEntryFlags::none },
-	{ "triggerHeight",				OBJECT_MODEL_FUNC(self->triggerHeight, 3), 							ObjectModelEntryFlags::none },
+	{ "triggerHeight",				OBJECT_MODEL_FUNC(-self->offsets[Z_AXIS], 3), 						ObjectModelEntryFlags::none },
 	{ "type",						OBJECT_MODEL_FUNC((int32_t)self->type), 							ObjectModelEntryFlags::none },
 	{ "value",						OBJECT_MODEL_FUNC_NOSELF(&valueArrayDescriptor), 					ObjectModelEntryFlags::live },
 };
@@ -102,7 +102,7 @@ void ZProbe::SetDefaults() noexcept
 	{
 		offset = 0.0;
 	}
-	triggerHeight = DefaultZProbeTriggerHeight;
+	offsets[Z_AXIS] = -DefaultZProbeTriggerHeight;
 	calibTemperature = DefaultZProbeTemperature;
 	for (float& tc : temperatureCoefficients)
 	{
@@ -128,10 +128,10 @@ float ZProbe::GetActualTriggerHeight() const noexcept
 		if (err == TemperatureError::success)
 		{
 			const float dt = temperature - calibTemperature;
-			return (dt * temperatureCoefficients[0]) + (fsquare(dt) * temperatureCoefficients[1]) + triggerHeight;
+			return (dt * temperatureCoefficients[0]) + (fsquare(dt) * temperatureCoefficients[1]) - offsets[Z_AXIS];
 		}
 	}
-	return triggerHeight;
+	return -offsets[Z_AXIS];
 }
 
 #if HAS_MASS_STORAGE
@@ -149,7 +149,7 @@ bool ZProbe::WriteParameters(FileStore *f, unsigned int probeNumber) const noexc
 			scratchString.catf(" %c%.1f", axisLetters[i], (double)offsets[i]);
 		}
 	}
-	scratchString.catf(" Z%.2f\n", (double)triggerHeight);
+	scratchString.catf(" Z%.2f\n", (double)-offsets[Z_AXIS]);
 	return f->Write(scratchString.c_str());
 }
 
@@ -327,7 +327,14 @@ GCodeResult ZProbe::HandleG31(GCodeBuffer& gb, const StringRef& reply) THROWS(GC
 			gb.TryGetFValue(axisLetters[i], offsets[i], seen);
 		}
 	}
-	gb.TryGetFValue(axisLetters[Z_AXIS], triggerHeight, seen);
+
+	{
+		float triggerHeight;
+		if (gb.TryGetFValue(axisLetters[Z_AXIS], triggerHeight, seen))
+		{
+			offsets[Z_AXIS] = -triggerHeight;				// logically, the Z offset of the Z probe is the negative of the trigger height
+		}
+	}
 
 	if (gb.Seen('P'))
 	{
@@ -353,7 +360,7 @@ GCodeResult ZProbe::HandleG31(GCodeBuffer& gb, const StringRef& reply) THROWS(GC
 		{
 			reply.catf(" (%d)", v1);
 		}
-		reply.catf(", threshold %d, trigger height %.3f", adcValue, (double)triggerHeight);
+		reply.catf(", threshold %d, trigger height %.3f", adcValue, (double)-offsets[Z_AXIS]);
 		if (temperatureCoefficients[0] != 0.0)
 		{
 			reply.catf(" at %.1f" DEGREE_SYMBOL "C, temperature coefficients [%.1f/" DEGREE_SYMBOL "C, %.1f/" DEGREE_SYMBOL "C^2]",
diff --git a/src/Endstops/ZProbe.h b/src/Endstops/ZProbe.h
index 9f5e9d7e..8cda06c9 100644
--- a/src/Endstops/ZProbe.h
+++ b/src/Endstops/ZProbe.h
@@ -35,7 +35,7 @@ public:
 
 	ZProbeType GetProbeType() const noexcept { return type; }
 	float GetOffset(size_t axisNumber) const noexcept { return offsets[axisNumber]; }
-	float GetConfiguredTriggerHeight() const noexcept { return triggerHeight; }
+	float GetConfiguredTriggerHeight() const noexcept { return -offsets[Z_AXIS]; }
 	float GetActualTriggerHeight() const noexcept;
 	float GetDiveHeight() const noexcept { return diveHeight; }
 	float GetStartingHeight() const noexcept { return diveHeight + GetActualTriggerHeight(); }
@@ -55,7 +55,7 @@ public:
 
 	void SetProbingAway(const bool probingAway) noexcept { misc.parts.probingAway = probingAway; }
 	GCodeResult HandleG31(GCodeBuffer& gb, const StringRef& reply) THROWS(GCodeException);
-	void SetTriggerHeight(float height) noexcept { triggerHeight = height; }
+	void SetTriggerHeight(float height) noexcept { offsets[Z_AXIS] = -height; }
 	void SetSaveToConfigOverride() noexcept { misc.parts.saveToConfigOverride = true; }
 	void SetDeployedByUser(bool b) noexcept { isDeployedByUser = b; }
 	void SetLastStoppedHeight(float h) noexcept;
@@ -88,8 +88,7 @@ protected:
 		} parts;
 		uint16_t all;
 	} misc;
-	float offsets[MaxAxes];				// the offset of the probe relative to the print head
-	float triggerHeight;				// the nozzle height at which the target ADC value is returned
+	float offsets[MaxAxes];				// the offset of the probe relative to the print head. The Z offset is the negation of the trigger height.
 	float calibTemperature;				// the temperature at which we did the calibration
 	float temperatureCoefficients[2];	// the variation of height with bed temperature and with the square of temperature
 	float diveHeight;					// the dive height we use when probing