path: root/src/Heating/LocalHeater.cpp

/*
 * Pid.cpp
 *
 *  Created on: 21 Jul 2016
 *      Author: David
 */

#include "LocalHeater.h"
#include <GCodes/GCodes.h>
#include <GCodes/GCodeBuffer/GCodeBuffer.h>
#include "Heat.h"
#include "HeaterMonitor.h"
#include <Platform/Platform.h>
#include <Platform/RepRap.h>
#include <Tools/Tool.h>

// Member functions and constructors

LocalHeater::LocalHeater(unsigned int heaterNum) noexcept : Heater(heaterNum), mode(HeaterMode::off)
{
	LocalHeater::ResetHeater();
	SetHeater(0.0);							// set up the pin even if the heater is not enabled (for PCCB)

	// Time the sensor was last sampled.  During startup, we use the current
	// time as the initial value so as to not trigger an immediate warning from the Tick ISR.
	lastSampleTime = millis();
}

LocalHeater::~LocalHeater() noexcept
{
	LocalHeater::SwitchOff();
	port.Release();
}

float LocalHeater::GetTemperature() const noexcept
{
	return temperature;
}

float LocalHeater::GetAccumulator() const noexcept
{
	return iAccumulator;
}

inline void LocalHeater::SetHeater(float power) const noexcept
{
	port.WriteAnalog(power);
}

void LocalHeater::ResetHeater() noexcept
{
	mode = HeaterMode::off;
	previousTemperaturesGood = 0;
	previousTemperatureIndex = 0;
	iAccumulator = 0.0;
	badTemperatureCount = 0;
	averagePWM = lastPwm = 0.0;
	heatingFaultCount = 0;
	temperature = BadErrorTemperature;
}

// Configure the heater port and the sensor number
GCodeResult LocalHeater::ConfigurePortAndSensor(const char *portName, PwmFrequency freq, unsigned int sn, const StringRef& reply)
{
	if (!port.AssignPort(portName, reply, PinUsedBy::heater, PinAccess::pwm))
	{
		return GCodeResult::error;
	}

	port.SetFrequency(freq);
	SetSensorNumber(sn);
	if (reprap.GetHeat().FindSensor(sn).IsNull())
	{
		reply.printf("Sensor number %u has not been defined", sn);
		return GCodeResult::warning;
	}
	return GCodeResult::ok;
}

GCodeResult LocalHeater::SetPwmFrequency(PwmFrequency freq, const StringRef& reply) noexcept
{
	port.SetFrequency(freq);
	return GCodeResult::ok;
}

GCodeResult LocalHeater::ReportDetails(const StringRef& reply) const noexcept
{
	reply.printf("Heater %u", GetHeaterNumber());
	port.AppendDetails(reply);
	if (GetSensorNumber() >= 0)
	{
		reply.catf(", sensor %d", GetSensorNumber());
	}
	else
	{
		reply.cat(", no sensor");
	}
	return GCodeResult::ok;
}

// Read and store the temperature of this heater and returns the error code.
TemperatureError LocalHeater::ReadTemperature() noexcept
{
	TemperatureError err;
	temperature = reprap.GetHeat().GetSensorTemperature(GetSensorNumber(), err);		// in the event of an error, err is set and BAD_ERROR_TEMPERATURE is returned
	return err;
}

// This must be called whenever the heater is turned on, and any time the heater is active and the target temperature is changed
GCodeResult LocalHeater::SwitchOn(const StringRef& reply) noexcept
{
	if (mode == HeaterMode::fault)
	{
		reply.printf("Heater %u not switched on due to temperature fault\n", GetHeaterNumber());
		return GCodeResult::warning;
	}

	//debugPrintf("Heater %d on, temp %.1f\n", heater, temperature);
	const float target = GetTargetTemperature();
	const HeaterMode oldMode = mode;
	mode = (temperature + TEMPERATURE_CLOSE_ENOUGH < target) ? HeaterMode::heating
			: (temperature > target + TEMPERATURE_CLOSE_ENOUGH) ? HeaterMode::cooling
				: HeaterMode::stable;
	if (mode != oldMode)
	{
		heatingFaultCount = 0;
		if (mode == HeaterMode::heating)
		{
			timeSetHeating = millis();
		}
		if (reprap.Debug(Module::moduleHeat) && oldMode == HeaterMode::off)
		{
			reprap.GetPlatform().MessageF(GenericMessage, "Heater %u switched on\n", GetHeaterNumber());
		}
	}
	return GCodeResult::ok;
}

// Switch off the specified heater. If in tuning mode, delete the array used to store tuning temperature readings.
void LocalHeater::SwitchOff() noexcept
{
	lastPwm = 0.0;
	if (GetModel().IsEnabled())
	{
		SetHeater(0.0);
		if (mode > HeaterMode::off)
		{
			mode = HeaterMode::off;
			if (reprap.Debug(Module::moduleHeat))
			{
				reprap.GetPlatform().MessageF(GenericMessage, "Heater %u switched off\n", GetHeaterNumber());
			}
		}
	}
}

// This is called when the heater model has been updated. Returns true if successful.
GCodeResult LocalHeater::UpdateModel(const StringRef& reply) noexcept
{
	return GCodeResult::ok;
}

// This is the main heater control loop function
void LocalHeater::Spin() noexcept
{
	// Read the temperature even if the heater is suspended or the model is not enabled
	const TemperatureError err = ReadTemperature();

	// Handle any temperature reading error and calculate the temperature rate of change, if possible
	if (err != TemperatureError::success)
	{
		previousTemperaturesGood <<= 1;				// this reading isn't a good one
		if (mode > HeaterMode::suspended)			// don't worry about errors when reading heaters that are switched off or flagged as having faults
		{
			// Error may be a temporary error and may correct itself after a few additional reads
			badTemperatureCount++;
			if (badTemperatureCount > MaxBadTemperatureCount)
			{
				RaiseHeaterFault("Temperature reading fault on heater %u: %s\n", GetHeaterNumber(), TemperatureErrorString(err));
			}
		}
		// We leave lastPWM alone if we have a temporary temperature reading error
	}
	else
	{
		// We have an apparently-good temperature reading. Calculate the derivative, if possible.
		float derivative = 0.0;
		bool gotDerivative = false;
		badTemperatureCount = 0;
		if ((previousTemperaturesGood & (1 << (NumPreviousTemperatures - 1))) != 0)
		{
			const float tentativeDerivative = (SecondsToMillis/(float)HeatSampleIntervalMillis) * (temperature - previousTemperatures[previousTemperatureIndex])
							/ (float)(NumPreviousTemperatures);
			// Some sensors give occasional temperature spikes. We don't expect the temperature to increase by more than 10C/second.
			if (fabsf(tentativeDerivative) <= 10.0)
			{
				derivative = tentativeDerivative;
				gotDerivative = true;
			}
		}
		previousTemperatures[previousTemperatureIndex] = temperature;
		previousTemperaturesGood = (previousTemperaturesGood << 1) | 1;

		if (GetModel().IsEnabled())
		{
			// Get the target temperature and the error
			const float targetTemperature = GetTargetTemperature();
			const float error = targetTemperature - temperature;

			// Do the heating checks
			switch(mode)
			{
			case HeaterMode::heating:
				{
					if (error <= TEMPERATURE_CLOSE_ENOUGH)
					{
						mode = HeaterMode::stable;
						heatingFaultCount = 0;
					}
					else if (gotDerivative)
					{
						const float expectedRate = GetExpectedHeatingRate();
						if (derivative + AllowedTemperatureDerivativeNoise < expectedRate
							&& (float)(millis() - timeSetHeating) > GetModel().GetDeadTime() * SecondsToMillis * 2)
						{
							++heatingFaultCount;
							if (heatingFaultCount * HeatSampleIntervalMillis > GetMaxHeatingFaultTime() * SecondsToMillis)
							{
								RaiseHeaterFault("Heater %u fault: temperature rising much more slowly than the expected %.1f" DEGREE_SYMBOL "C/sec\n",
													GetHeaterNumber(), (double)expectedRate);
							}
						}
						else if (heatingFaultCount != 0)
						{
							--heatingFaultCount;
						}
					}
					else
					{
						// Leave the heating fault count alone
					}
				}
				break;

			case HeaterMode::stable:
				if (fabsf(error) > GetMaxTemperatureExcursion() && temperature > MaxAmbientTemperature)
				{
					++heatingFaultCount;
					if (heatingFaultCount * HeatSampleIntervalMillis > GetMaxHeatingFaultTime() * SecondsToMillis)
					{
						RaiseHeaterFault("Heater %u fault: temperature excursion exceeded %.1f" DEGREE_SYMBOL "C (target %.1f" DEGREE_SYMBOL "C, actual %.1f" DEGREE_SYMBOL "C)\n",
											GetHeaterNumber(), (double)GetMaxTemperatureExcursion(), (double)targetTemperature, (double)temperature);
					}
				}
				else if (heatingFaultCount != 0)
				{
					--heatingFaultCount;
				}
				break;

			case HeaterMode::cooling:
				if (-error <= TEMPERATURE_CLOSE_ENOUGH && targetTemperature > MaxAmbientTemperature)
				{
					// We have cooled to close to the target temperature, so we should now maintain that temperature
					mode = HeaterMode::stable;
					heatingFaultCount = 0;
				}
				else
				{
					// We could check for temperature excessive or not falling here, but without an alarm or a power-off mechanism, there is not much we can do
					// TODO emergency stop?
				}
				break;

			default:		// this covers off, fault, suspended, and the auto tuning states
				break;
			}

			// Calculate the PWM
			if (mode >= HeaterMode::tuning0)
			{
				DoTuningStep();
			}
			else
			{
				if (mode <= HeaterMode::suspended)
				{
					lastPwm = 0.0;
				}
				else
				{
					// Performing normal temperature control
					if (GetModel().UsePid())
					{
						// Using PID mode. Determine the PID parameters to use.
						const bool inLoadMode = (mode == HeaterMode::stable) || fabsf(error) < 3.0;		// use standard PID when maintaining temperature
						const PidParameters& params = GetModel().GetPidParameters(inLoadMode);

						// If the P and D terms together demand that the heater is full on or full off, disregard the I term
						const float errorMinusDterm = error - (params.tD * derivative);
						const float pPlusD = params.kP * errorMinusDterm;
						const float expectedPwm = constrain<float>((temperature - NormalAmbientTemperature)/GetModel().GetGainFanOff(), 0.0, GetModel().GetMaxPwm());
						if (pPlusD + expectedPwm > GetModel().GetMaxPwm())
						{
							lastPwm = GetModel().GetMaxPwm();
							// If we are heating up, preset the I term to the expected PWM at this temperature, ready for the switch over to PID
							if (mode == HeaterMode::heating && error > 0.0 && derivative > 0.0)
							{
								iAccumulator = expectedPwm;
							}
						}
						else if (pPlusD + expectedPwm < 0.0)
						{
							lastPwm = 0.0;
						}
						else
						{
							const float errorToUse = error;
							iAccumulator = constrain<float>
											(iAccumulator + (errorToUse * params.kP * params.recipTi * (HeatSampleIntervalMillis * MillisToSeconds)),
												0.0, GetModel().GetMaxPwm());
							lastPwm = constrain<float>(pPlusD + iAccumulator, 0.0, GetModel().GetMaxPwm());
						}
#if HAS_VOLTAGE_MONITOR
						// Scale the PID based on the current voltage vs. the calibration voltage
						if (lastPwm < 1.0 && GetModel().GetVoltage() >= 10.0)				// if heater is not fully on and we know the voltage we tuned the heater at
						{
							if (!reprap.GetHeat().IsBedOrChamberHeater(GetHeaterNumber()))
							{
								const float currentVoltage = reprap.GetPlatform().GetCurrentPowerVoltage();
								if (currentVoltage >= 10.0)				// if we have a sensible reading
								{
									lastPwm = min<float>(lastPwm * fsquare(GetModel().GetVoltage()/currentVoltage), 1.0);	// adjust the PWM by the square of the voltage ratio
								}
							}
						}
#endif
					}
					else
					{
						// Using bang-bang mode
						lastPwm = (error > 0.0) ? GetModel().GetMaxPwm() : 0.0;
					}

					// Check if the generated PWM signal needs to be inverted for inverse temperature control
					if (GetModel().IsInverted())
					{
						lastPwm = GetModel().GetMaxPwm() - lastPwm;
					}
				}

				// Verify that everything is operating in the required temperature range
				for (size_t i = 0; i < ARRAY_SIZE(monitors); ++i)
				{
					HeaterMonitor& prot = monitors[i];
					if (!prot.Check())
					{
						lastPwm = 0.0;
						switch (prot.GetAction())
						{
						case HeaterMonitorAction::ShutDown:
							reprap.GetHeat().SwitchOffAll(true);
							reprap.GetPlatform().AtxPowerOff(false);
							break;

						case HeaterMonitorAction::GenerateFault:
							RaiseHeaterFault("Heater %u fault: heater monitor %u was triggered\n", GetHeaterNumber(), i);
							break;

						case HeaterMonitorAction::TemporarySwitchOff:
							// Do nothing, the PWM value has already been set above
							break;

						case HeaterMonitorAction::PermanentSwitchOff:
							if (mode != HeaterMode::fault)
							{
								SwitchOff();
							}
							break;
						}
					}
				}
			}
		}
		else
		{
			lastPwm = 0.0;
		}

		// Set the heater power and update the average PWM
		SetHeater(lastPwm);
		averagePWM = averagePWM * (1.0 - HeatSampleIntervalMillis/(HeatPwmAverageTime * SecondsToMillis)) + lastPwm;
		previousTemperatureIndex = (previousTemperatureIndex + 1) % NumPreviousTemperatures;

		// For temperature sensors which do not require frequent sampling and averaging,
		// their temperature is read here and error/safety handling performed.  However,
		// unlike the Tick ISR, this code is not executed at interrupt level and consequently
		// runs the risk of having undesirable delays between calls.  To guard against this,
		// we record for each PID object when it was last sampled and have the Tick ISR
		// take action if there is a significant delay since the time of last sampling.
		lastSampleTime = millis();

//  	debugPrintf("Heater %d: e=%f, P=%f, I=%f, d=%f, r=%f\n", heater, error, pp.kP*error, temp_iState, temp_dState, result);
	}
}

GCodeResult LocalHeater::ResetFault(const StringRef& reply) noexcept
{
	badTemperatureCount = 0;
	if (mode == HeaterMode::fault)
	{
		mode = HeaterMode::off;
		SwitchOff();
	}
	return GCodeResult::ok;
}

float LocalHeater::GetAveragePWM() const noexcept
{
	return averagePWM * HeatSampleIntervalMillis/(HeatPwmAverageTime * SecondsToMillis);
}

// Get a conservative estimate of the expected heating rate at the current temperature and average PWM. The result may be negative.
float LocalHeater::GetExpectedHeatingRate() const noexcept
{
	// In the following we allow for the gain being only 75% of what we think it should be, to avoid false alarms
	const float maxTemperatureRise = 0.75 * GetModel().GetGainFanOff() * GetAveragePWM();	// this is the highest temperature above ambient we expect the heater can reach at this PWM
	const float initialHeatingRate = maxTemperatureRise/GetModel().GetTimeConstantFanOn();	// this is the expected heating rate at ambient temperature
	return (maxTemperatureRise >= 20.0)
			? (maxTemperatureRise + NormalAmbientTemperature - temperature) * initialHeatingRate/maxTemperatureRise
			: 0.0;
}

// Auto tune this heater. The caller has already checked that on other heater is being tuned.
GCodeResult LocalHeater::StartAutoTune(const StringRef& reply, FansBitmap fans, float targetTemp, float pwm, bool seenA, float ambientTemp) noexcept
{
	if (lastPwm > 0.0 || GetAveragePWM() > 0.02)
	{
		reply.printf("heater %u must be off and cold before auto tuning it", GetHeaterNumber());
		return GCodeResult::error;
	}

	tuningFans = fans;
	reprap.GetFansManager().SetFansValue(tuningFans, 0.0);

	tuningPwm = pwm;
	tuningTargetTemp = targetTemp;
	tuningStartTemp.Clear();
	tuningBeginTime = millis();
	tuned = false;					// assume failure

	if (seenA)
	{
		tuningStartTemp.Add(ambientTemp);
		ClearCounters();
		timeSetHeating = millis();
		lastPwm = tuningPwm;										// turn on heater at specified power
		tuningPhase = 1;
		mode = HeaterMode::tuning1;
		ReportTuningUpdate();
	}
	else
	{
		tuningPhase = 0;
		mode = HeaterMode::tuning0;
	}

	return GCodeResult::ok;
}

// Call this when the PWM of a cooling fan has changed. If there are multiple fans, caller must divide pwmChange by the number of fans.
void LocalHeater::FeedForwardAdjustment(float fanPwmChange, float extrusionChange) noexcept
{
	if (mode == HeaterMode::stable)
	{
		const float coolingRateIncrease = GetModel().GetCoolingRateChangeFanOn() * fanPwmChange;
		const float boost = (coolingRateIncrease * (GetTargetTemperature() - NormalAmbientTemperature) * FeedForwardMultiplier)/GetModel().GetHeatingRate();
#if 0
		if (reprap.Debug(moduleHeat))
		{
			debugPrintf("iacc=%.3f, applying boost %.3f\n", (double)iAccumulator, (double)boost);
		}
#endif
		TaskCriticalSectionLocker lock;
		iAccumulator += boost;
	}
}

/* Notes on the auto tune algorithm
 *
 * Most 3D printer firmwares use the �str�m-H�gglund relay tuning method (sometimes called Ziegler-Nichols + relay).
 * This gives results  of variable quality, but they seem to be generally satisfactory.
 *
 * We use Cohen-Coon tuning instead. This models the heating process as a first-order process (i.e. one that with constant heating
 * power approaches the equilibrium temperature exponentially) with dead time. This process is defined by three constants:
 *
 *  G is the gain of the system, i.e. the increase in ultimate temperature increase per unit of additional PWM
 *  td is the dead time, i.e. the time between increasing the heater PWM and the temperature following an exponential curve
 *  tc is the time constant of the exponential curve
 *
 * If the temperature is stable at T0 to begin with, the temperature at time t after increasing heater PWM by p is:
 *  T = T0 when t <= td
 *  T = T0 + G * p * (1 - exp((t - td)/tc)) when t >= td
 * In practice the transition from no change to the exponential curve is not instant, however this model is a reasonable approximation.
 *
 * Having a process model allows us to preset the I accumulator to a suitable value when switching between heater full on/off and using PID.
 * It will also make it easier to include feedforward terms in future.
 *
 * We can calculate the P, I and D parameters from G, td and tc using the modified Cohen-Coon tuning rules, or the Ho et al tuning rules.
 *    Cohen-Coon (modified to use half the original Kc value):
 *     Kc = (0.67/G) * (tc/td + 0.185)
 *     Ti = 2.5 * td * (tc + 0.185 * td)/(tc + 0.611 * td)
 *     Td = 0.37 * td * tc/(tc + 0.185 * td)
 *    Ho et al, best response to load changes:
 *     Kc = (1.435/G) * (td/tc)^-0.921
 *     Ti = 1.14 * (td/tc)^0.749
 *     Td = 0.482 * tc * (td/tc)^1.137
 *    Ho et al, best response to setpoint changes:
 *     Kc = (1.086/G) * (td/tc)^-0.869
 *     Ti = tc/(0.74 - 0.13 * td/tc)
 *     Td = 0.348 * tc * (td/tc)^0.914
 */

// This is called on each temperature sample when auto tuning
// It must set lastPWM to the required PWM before returning, unless it is the same as last time.
void LocalHeater::DoTuningStep() noexcept
{
	const uint32_t now = millis();
	switch (mode)
	{
	case HeaterMode::tuning0:		// Waiting for initial temperature to settle after any thermostatic fans have turned on
		if (tuningStartTemp.GetNumSamples() < 5000/HeatSampleIntervalMillis)
		{
			tuningStartTemp.Add(temperature);							// take another reading until we have samples temperatures for 5 seconds
			return;
		}

		if (tuningStartTemp.GetDeviation() <= 2.0)
		{
			timeSetHeating = now;
			lastPwm = tuningPwm;										// turn on heater at specified power
			mode = HeaterMode::tuning1;

			reprap.GetPlatform().Message(GenericMessage, "Auto tune starting phase 1, heater on\n");
			return;
		}

		if (now - tuningBeginTime < 20000)
		{
			// Allow up to 20 seconds for starting temperature to settle
			return;
		}

		reprap.GetPlatform().Message(GenericMessage, "Auto tune cancelled because starting temperature is not stable\n");
		break;

	case HeaterMode::tuning1:		// Heating up
		tuningPhase = 1;
		{
			const bool isBedOrChamberHeater = reprap.GetHeat().IsBedOrChamberHeater(GetHeaterNumber());
			const uint32_t heatingTime = now - timeSetHeating;
			const float extraTimeAllowed = (isBedOrChamberHeater) ? 120.0 : 30.0;
			if (heatingTime > (uint32_t)((GetModel().GetDeadTime() + extraTimeAllowed) * SecondsToMillis) && (temperature - tuningStartTemp.GetMean()) < 3.0)
			{
				reprap.GetPlatform().Message(GenericMessage, "Auto tune cancelled because temperature is not increasing\n");
				break;
			}

			const uint32_t timeoutMinutes = (isBedOrChamberHeater) ? 30 : 7;
			if (heatingTime >= timeoutMinutes * 60 * (uint32_t)SecondsToMillis)
			{
				reprap.GetPlatform().Message(GenericMessage, "Auto tune cancelled because target temperature was not reached\n");
				break;
			}

			if (temperature >= tuningTargetTemp)							// if reached target
			{
				// Move on to next phase
				lastPwm = 0.0;
				SetHeater(0.0);
				peakTemp = afterPeakTemp = temperature;
				lastOffTime = peakTime = afterPeakTime = now;
				tuningVoltage.Clear();
				idleCyclesDone = 0;
				mode = HeaterMode::tuning2;
				tuningPhase = 2;
				ReportTuningUpdate();
			}
		}
		return;

	case HeaterMode::tuning2:		// Heater is off, record the peak temperature and time
		if (temperature >= peakTemp)
		{
			peakTemp = afterPeakTemp = temperature;
			peakTime = afterPeakTime = now;
		}
		else if (temperature < tuningTargetTemp - TuningHysteresis)
		{
			// Temperature has dropped below the low limit.
			// If we have been doing idle cycles, see whether we can switch to collecting data, and turn the heater on.
			// If we have been collecting data, see if we have enough, and either turn the heater on to start another cycle or finish tuning.

			// Save the data (don't know whether we need it yet)
			dHigh.Add((float)(peakTime - lastOffTime));
			tOff.Add((float)(now - lastOffTime));
			const float currentCoolingRate = (afterPeakTemp - temperature) * SecondsToMillis/(now - afterPeakTime);
			coolingRate.Add(currentCoolingRate);

			// Decide whether to finish this phase
			if (tuningPhase == 2)				// if we are doing idle cycles
			{
				// To allow for heat reservoirs, we do idle cycles until the cooling rate decreases by no more than a certain amount in a single cycle
				if (idleCyclesDone == TuningHeaterMaxIdleCycles || (idleCyclesDone >= TuningHeaterMinIdleCycles && currentCoolingRate >= lastCoolingRate * HeaterSettledCoolingTimeRatio))
				{
					tuningPhase = 3;
					ReportTuningUpdate();
				}
				else
				{
					lastCoolingRate = currentCoolingRate;
					ClearCounters();
					++idleCyclesDone;
				}
			}
			else if (coolingRate.GetNumSamples() >= MinTuningHeaterCycles)
			{
				const bool isConsistent = dLow.DeviationFractionWithin(0.2)
										&& dHigh.DeviationFractionWithin(0.2)
										&& heatingRate.DeviationFractionWithin(0.1)
										&& coolingRate.DeviationFractionWithin(0.1);
				if (isConsistent || coolingRate.GetNumSamples() == MaxTuningHeaterCycles)
				{
					if (!isConsistent)
					{
						reprap.GetPlatform().Message(WarningMessage, "heater behaviour was not consistent during tuning\n");
					}

					if (tuningPhase == 3)
					{
						CalculateModel(fanOffParams);
						if (tuningFans.IsEmpty())
						{
							SetAndReportModel(false);
							break;
						}
						else
						{
							tuningPhase = 4;
							ClearCounters();
#if TUNE_WITH_HALF_FAN
							reprap.GetFansManager().SetFansValue(tuningFans, 0.5);		// turn fans on at half PWM
#else
							reprap.GetFansManager().SetFansValue(tuningFans, 1.0);		// turn fans on at full PWM
#endif
							ReportTuningUpdate();
						}
					}
#if TUNE_WITH_HALF_FAN
					else if (tuningPhase == 4)
					{
						CalculateModel(fanOnParams);
						tuningPhase = 5;
						ClearCounters();
						reprap.GetFansManager().SetFansValue(tuningFans, 1.0);			// turn fans fully on
						ReportTuningUpdate();
					}
#endif
					else
					{
						reprap.GetFansManager().SetFansValue(tuningFans, 0.0);			// turn fans off
						CalculateModel(fanOnParams);
						SetAndReportModel(true);
						break;
					}
				}
			}
			lastOnTime = peakTime = afterPeakTime = now;
			peakTemp = afterPeakTemp = temperature;
			lastPwm = tuningPwm;						// turn on heater at specified power
			mode = HeaterMode::tuning3;
		}
		else if (afterPeakTime == peakTime && tuningTargetTemp - temperature >= TuningPeakTempDrop)
		{
			afterPeakTime = now;
			afterPeakTemp = temperature;
		}
		return;

	case HeaterMode::tuning3:	// Heater is turned on, record the lowest temperature and time
#if HAS_VOLTAGE_MONITOR
		tuningVoltage.Add(reprap.GetPlatform().GetCurrentPowerVoltage());
#endif
		if (temperature <= peakTemp)
		{
			peakTemp = afterPeakTemp = temperature;
			peakTime = afterPeakTime = now;
		}
		else if (temperature >= tuningTargetTemp)
		{
			// We have reached the target temperature, so record a data point and turn the heater off
			dLow.Add((float)(peakTime - lastOnTime));
			tOn.Add((float)(now - lastOnTime));
			heatingRate.Add((temperature - afterPeakTemp) * SecondsToMillis/(now - afterPeakTime));
			lastOffTime = peakTime = afterPeakTime = now;
			peakTemp = afterPeakTemp = temperature;
			lastPwm = 0.0;								// turn heater off
			mode = HeaterMode::tuning2;
		}
		else if (afterPeakTime == peakTime && temperature - tuningTargetTemp >= TuningPeakTempDrop - TuningHysteresis)
		{
			afterPeakTime = now;
			afterPeakTemp = temperature;
		}
		return;

	default:
		// Should not happen, but if it does then quit
		break;
	}

	// If we get here, we have finished
	SwitchOff();								// sets mode and lastPWM, also deletes tuningTempReadings
}

// Calculate the heater model from the accumulated heater parameters
// Suspend the heater, or resume it
void LocalHeater::Suspend(bool sus) noexcept
{
	if (sus)
	{
		if (mode == HeaterMode::stable || mode == HeaterMode::heating || mode == HeaterMode::cooling)
		{
			mode = HeaterMode::suspended;
			SetHeater(0.0);
			lastPwm = 0.0;
		}
	}
	else if (mode == HeaterMode::suspended)
	{
		String<1> dummy;
		(void)SwitchOn(dummy.GetRef());
	}
}

void LocalHeater::RaiseHeaterFault(const char *format, ...) noexcept
{
	lastPwm = 0.0;
	SetHeater(0.0);
	if (mode != HeaterMode::fault)
	{
		mode = HeaterMode::fault;
		va_list vargs;
		va_start(vargs, format);
		reprap.GetPlatform().MessageF(ErrorMessage, format, vargs);
		va_end(vargs);
	}
	reprap.GetGCodes().HandleHeaterFault();
	reprap.FlagTemperatureFault(GetHeaterNumber());
}

// End