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diff --git a/src/Heating/Sensors/CurrentLoopTemperatureSensor.cpp b/src/Heating/Sensors/CurrentLoopTemperatureSensor.cpp
new file mode 100644
index 00000000..388fdbc8
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+++ b/src/Heating/Sensors/CurrentLoopTemperatureSensor.cpp
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+/*
+ * LinearAdcTemperatureSensor.cpp
+ *
+ *  Created on: 8 Jun 2017
+ *      Author: David
+ */
+
+#include <Heating/Sensors/CurrentLoopTemperatureSensor.h>
+#include "RepRap.h"
+#include "Platform.h"
+#include "GCodes/GCodeBuffer.h"
+
+const uint32_t MCP3204_Frequency = 1000000;		// maximum for MCP3204 is 1MHz @ 2.7V, will be slightly higher at 3.3V
+
+// The MCP3204 samples input data on the rising edge and changes the output data on the rising edge.
+const uint8_t MCP3204_SpiMode = SPI_MODE_0;
+
+// Define the minimum interval between readings
+const uint32_t MinimumReadInterval = 100;		// minimum interval between reads, in milliseconds
+
+CurrentLoopTemperatureSensor::CurrentLoopTemperatureSensor(unsigned int channel)
+	: SpiTemperatureSensor(channel, "Current Loop", channel - FirstLinearAdcChannel, MCP3204_SpiMode, MCP3204_Frequency),
+	  tempAt4mA(DefaultTempAt4mA), tempAt20mA(DefaultTempAt20mA)
+{
+	CalcDerivedParameters();
+}
+
+// Initialise the linear ADC
+void CurrentLoopTemperatureSensor::Init()
+{
+	InitSpi();
+
+	for (unsigned int i = 0; i < 3; ++i)		// try 3 times
+	{
+		TryGetLinearAdcTemperature();
+		if (lastResult == TemperatureError::success)
+		{
+			break;
+		}
+		delay(MinimumReadInterval);
+	}
+
+	lastReadingTime = millis();
+
+	if (lastResult != TemperatureError::success)
+	{
+		reprap.GetPlatform().MessageF(GENERIC_MESSAGE, "Error: failed to initialise daughter board ADC: %s\n", TemperatureErrorString(lastResult));
+	}
+}
+
+// Configure this temperature sensor
+bool CurrentLoopTemperatureSensor::Configure(unsigned int mCode, unsigned int heater, GCodeBuffer& gb, StringRef& reply, bool& error)
+{
+	if (mCode == 305)
+	{
+		bool seen = false;
+		gb.TryGetFValue('L', tempAt4mA, seen);
+		gb.TryGetFValue('H', tempAt20mA, seen);
+		TryConfigureHeaterName(gb, seen);
+
+		if (seen)
+		{
+			CalcDerivedParameters();
+		}
+		else if (!gb.Seen('X'))
+		{
+			CopyBasicHeaterDetails(heater, reply);
+			reply.catf(", temperature range %.1f to %.1fC", tempAt4mA, tempAt20mA);
+		}
+	}
+	return false;
+}
+
+TemperatureError CurrentLoopTemperatureSensor::GetTemperature(float& t)
+{
+	if (!inInterrupt() && millis() - lastReadingTime >= MinimumReadInterval)
+	{
+		TryGetLinearAdcTemperature();
+	}
+
+	t = lastTemperature;
+	return lastResult;
+}
+
+void CurrentLoopTemperatureSensor::CalcDerivedParameters()
+{
+	minLinearAdcTemp = tempAt4mA - 0.25 * (tempAt20mA - tempAt4mA);
+	linearAdcDegCPerCount = (tempAt20mA - minLinearAdcTemp) / 4096.0;
+}
+
+// Try to get a temperature reading from the linear ADC by doing an SPI transaction
+void CurrentLoopTemperatureSensor::TryGetLinearAdcTemperature()
+{
+	// The MCP3204 waits for a high input input bit before it does anything. Call this clock 1.
+	// The next input bit it high for single-ended operation, low for differential. This is clock 2.
+	// The next 3 input bits are the channel selection bits. These are clocks 3..5.
+	// Clock 6 produces a null bit on its trailing edge, which is read by the processor on clock 7.
+	// Clocks 7..18 produce data bits B11..B0 on their trailing edges, which are read by the MCU on the leading edges of clocks 8-19.
+	// If we supply further clocks, then clocks 18..29 are the same data but LSB first, omitting bit 0.
+	// Clocks 30 onwards will be zeros.
+	// So we need to use at least 19 clocks. We round this up to 24 clocks, and we check that the extra 5 bits we receive are the 5 least significant data bits in reverse order.
+
+	static const uint8_t adcData[] = { 0xC0, 0x00, 0x00 };		// start bit, single ended, channel 0
+	uint32_t rawVal;
+	lastResult = DoSpiTransaction(adcData, 3, rawVal);
+	//debugPrintf("ADC data %u\n", rawVal);
+
+	if (lastResult == TemperatureError::success)
+	{
+		const uint32_t adcVal1 = (rawVal >> 5) & ((1 << 13) - 1);
+		const uint32_t adcVal2 = ((rawVal & 1) << 5) | ((rawVal & 2) << 3) | ((rawVal & 4) << 1) | ((rawVal & 8) >> 1) | ((rawVal & 16) >> 3) | ((rawVal & 32) >> 5);
+		if (adcVal1 >= 4096 || adcVal2 != (adcVal1 & ((1 << 6) - 1)))
+		{
+			lastResult = TemperatureError::badResponse;
+		}
+		else
+		{
+			lastTemperature = minLinearAdcTemp + (linearAdcDegCPerCount * (float)adcVal1);
+		}
+	}
+}
+
+// End