Added temperature and relay nodes

lib/HomieNodes/SensorNode.cpp

@@ -0,0 +1,48 @@
+/*
+ * SensorNode.hpp
+ * Homie Node for genric sensors.
+ * Provides a limit method for measurement values
+ *
+ * Version: 1.0
+ * Author: Lübbe Onken (http://github.com/luebbe)
+ */
+
+#include "SensorNode.hpp"
+
+SensorNode::SensorNode(const char *name, const char *type)
+    : HomieNode(name, type, "sensor")
+{
+}
+
+float SensorNode::computeAbsoluteHumidity(float temperature, float percentHumidity) {
+  // Calculate the absolute humidity in g/m³
+  // https://carnotcycle.wordpress.com/2012/08/04/how-to-convert-relative-humidity-to-absolute-humidity/
+
+  float absHumidity;
+  float absTemperature;
+  absTemperature = temperature + 273.15;
+
+  absHumidity = 6.112;
+  absHumidity *= exp((17.67 * temperature) / (243.5 + temperature));
+  absHumidity *= percentHumidity;
+  absHumidity *= 2.1674;
+  absHumidity /= absTemperature;
+
+  return absHumidity;
+}
+
+void SensorNode::fixRange(float *value, float min, float max)
+{
+  if (isnan(*value))
+  {
+    return;
+  }
+  else if (*value < min)
+  {
+    *value = min;
+  }
+  else if (*value > max)
+  {
+    *value = max;
+  };
+}