Added ability to read TC voltage. Also changed return type from float to double precision

Author: JHSawatzki

src/utility/THERMOCOUPLE/MAX31855.cpp

@@ -134,7 +134,7 @@ double MAX31855Class::mvtoTemp(double voltage) {
     return polynomial(voltage, tableEntries, table);
 }
 
-float MAX31855Class::readTCTemperature() {
+double MAX31855Class::readTCVoltage() {
     uint32_t rawword;
     int32_t measuredTempInt;
     int32_t measuredColdInt;
@@ -189,6 +189,12 @@ float MAX31855Class::readTCTemperature() {
 
     measuredVolt = tempTomv(measuredCold - _coldOffset) + (measuredTemp - measuredCold) * 0.041276f;
 
+    return measuredVolt;
+}
+
+double MAX31855Class::readTCTemperature() {
+    measuredVolt = readTCVoltage();
+
     // finally from the cold junction compensated voltage we calculate the temperature
     // using NIST polynomial approximation for the thermocouple type we are using
     return mvtoTemp(measuredVolt);

src/utility/THERMOCOUPLE/MAX31855.h

@@ -27,7 +27,8 @@ class MAX31855Class {
     bool begin();
     void end();
 
-    float readTCTemperature();
+    double readTCVoltage();
+    double readTCTemperature();
     float readReferenceTemperature();
     void setColdOffset(float offset);