Temperature A to D readings now done using a moving average, like the Z probe.

Platform.cpp

@@ -204,6 +204,7 @@ void Platform::Init()
     if(heatOnPins[i] >= 0)
       pinModeNonDue(heatOnPins[i], OUTPUT);
     thermistorInfRs[i] = ( thermistorInfRs[i]*exp(-thermistorBetas[i]/(25.0 - ABS_ZERO)) );
+    tempSum[i] = 0;
   }
 
   if(coolingFanPin >= 0)
@@ -212,6 +213,8 @@ void Platform::Init()
 	  analogWrite(coolingFanPin, 0);
   }
 
+  NumAtoDReadingsAveraged = 8;	// must be an even number, preferably a power of 2 for performance, and no greater than 64
+
   InitialiseInterrupts();
   
   addToTime = 0.0;
@@ -251,6 +254,7 @@ void Platform::Spin()
   if(Time() - lastTime < 0.006)
     return;
   PollZHeight();
+  PollTemperatures();
   lastTime = Time();
   ClassReport("Platform", longWait);
 
@@ -359,15 +363,18 @@ void Platform::ClassReport(char* className, float &lastTime)
 float Platform::GetTemperature(int8_t heater)
 {
   // If the ADC reading is N then for an ideal ADC, the input voltage is at least N/(AD_RANGE + 1) and less than (N + 1)/(AD_RANGE + 1), times the analog reference.
-  // So we add 0.5 to to the reading to get a better estimate of the input. But first, recognise the special case of thermistor disconnected.
+  // So we add 0.5 to to the reading to get a better estimate of the input.
-  int rawTemp = GetRawTemperature(heater);
+  int rawTemp = tempSum[heater]/NumAtoDReadingsAveraged; //GetRawTemperature(heater);
-  if (rawTemp == AD_RANGE)
+
-  {
+  // First, recognise the special case of thermistor disconnected.
-	  // Thermistor is disconnected
+//  if (rawTemp == AD_RANGE)
-	  return ABS_ZERO;
+//  {
-  }
+//	  // Thermistor is disconnected
+//	  return ABS_ZERO;
+//  }
   float r = (float)rawTemp + 0.5;
-  return ABS_ZERO + thermistorBetas[heater]/log( (r*thermistorSeriesRs[heater]/((AD_RANGE + 1) - r))/thermistorInfRs[heater] );
+  r = ABS_ZERO + thermistorBetas[heater]/log( (r*thermistorSeriesRs[heater]/((AD_RANGE + 1) - r))/thermistorInfRs[heater] );
+  return r;
 }
 
 

Platform.h

@@ -189,7 +189,6 @@ const unsigned int httpOutputBufferSize = 2 * 1432;
 #define BAUD_RATE 115200 						// Communication speed of the USB if needed.
 
 const uint16_t lineBufsize = 256;				// use a power of 2 for good performance
-const uint16_t NumZProbeReadingsAveraged = 8;	// must be an even number, preferably a power of 2 for performance, and no greater than 64
 
 /****************************************************************************************************/
 
@@ -549,6 +548,7 @@ class Platform
   int zProbeADValue;
   float zProbeStopHeight;
   bool zProbeEnable;
+
 // AXES
 
   void InitZProbe();
@@ -557,14 +557,13 @@ class Platform
   float axisLengths[AXES];
   float homeFeedrates[AXES];
   float headOffsets[AXES]; // FIXME - needs a 2D array
-//  bool zProbeStarting;
-//  float zProbeHigh;
-//  float zProbeLow;
   
 // HEATERS - Bed is assumed to be the first
 
   int GetRawTemperature(byte heater) const;
+  void PollTemperatures();
 
+  long tempSum[HEATERS];
   int8_t tempSensePins[HEATERS];
   int8_t heatOnPins[HEATERS];
   float thermistorBetas[HEATERS];
@@ -582,7 +581,8 @@ class Platform
   float standbyTemperatures[HEATERS];
   float activeTemperatures[HEATERS];
   int8_t coolingFanPin;
-  //int8_t turnHeatOn;
+
+  uint16_t NumAtoDReadingsAveraged;  // Smoothing filter on A to D readings
 
 // Serial/USB
 
@@ -815,10 +815,12 @@ inline void Platform::PollZHeight()
 {
 	uint16_t currentReading = GetRawZHeight();
 
+	// We do a moving average of the probe's A to D readings to smooth out noise
+
 	if (zModOnThisTime)
-		zProbeOnSum = zProbeOnSum + currentReading - zProbeOnSum/NumZProbeReadingsAveraged;
+		zProbeOnSum = zProbeOnSum + currentReading - zProbeOnSum/NumAtoDReadingsAveraged;
 	else
-		zProbeOffSum = zProbeOffSum + currentReading - zProbeOffSum/NumZProbeReadingsAveraged;
+		zProbeOffSum = zProbeOffSum + currentReading - zProbeOffSum/NumAtoDReadingsAveraged;
 
 	zModOnThisTime = !zModOnThisTime;
 
@@ -832,18 +834,18 @@ inline void Platform::PollZHeight()
 inline int Platform::ZProbe() const
 {
 	return (zProbeType == 1)
-			? (zProbeOnSum + zProbeOffSum)/NumZProbeReadingsAveraged		// non-modulated mode
+			? (zProbeOnSum + zProbeOffSum)/NumAtoDReadingsAveraged		// non-modulated mode
 			: (zProbeType == 2)
-			  ? (zProbeOnSum - zProbeOffSum)/(NumZProbeReadingsAveraged/2)	// modulated mode
+			  ? (zProbeOnSum - zProbeOffSum)/(NumAtoDReadingsAveraged/2)	// modulated mode
 			    : 0;														// z-probe disabled
 }
 
 inline int Platform::ZProbeOnVal() const
 {
 	return (zProbeType == 1)
-			? (zProbeOnSum + zProbeOffSum)/NumZProbeReadingsAveraged
+			? (zProbeOnSum + zProbeOffSum)/NumAtoDReadingsAveraged
 			: (zProbeType == 2)
-			  ? zProbeOnSum/(NumZProbeReadingsAveraged/2)
+			  ? zProbeOnSum/(NumAtoDReadingsAveraged/2)
 				: 0;
 }
 
@@ -887,6 +889,14 @@ inline int Platform::GetRawTemperature(byte heater) const
   return 0;
 }
 
+inline void Platform::PollTemperatures()
+{
+	// We do a moving average of each thermometer's A to D readings to smooth out noise
+
+	for(int8_t heater = 0; heater < HEATERS; heater++)
+		tempSum[heater] = tempSum[heater] + GetRawTemperature(heater) - tempSum[heater]/NumAtoDReadingsAveraged;
+}
+
 inline float Platform::HeatSampleTime() const
 {
   return heatSampleTime;