Extend temperature conversion API

Add a stateful millisTowaitForConversion (class knows the resolution)

Make millisToWaitForConversion(uint8_t) static

Add celsiusToRaw

Return signed int from celsiusToRaw

Add a description to celsiusToRaw

Author: mkrzewic

DallasTemperature.cpp

@@ -469,6 +469,11 @@ uint16_t DallasTemperature::millisToWaitForConversion(uint8_t bitResolution) {
 
 }
 
+// returns number of milliseconds to wait till conversion is complete (based on IC datasheet)
+uint16_t DallasTemperature::millisToWaitForConversion() {
+  return millisToWaitForConversion(bitResolution);
+}
+
 // Sends command to one device to save values from scratchpad to EEPROM by index
 // Returns true if no errors were encountered, false indicates failure
 bool DallasTemperature::saveScratchPadByIndex(uint8_t deviceIndex) {
@@ -740,6 +745,19 @@ float DallasTemperature::rawToCelsius(int16_t raw) {
 
 }
 
+// Convert from Celsius to raw returns temperature in raw integer format.
+// The rounding error in the conversion is smaller than 0.01°C
+// where the resolution of the sensor is at best 0.0625°C (in 12 bit mode).
+// Rounding error can be verified by running:
+//  for (float t=-55.; t<125.; t+=0.01)
+//  {
+//    Serial.println( DallasTemperature::rawToCelsius(DallasTemperature::celsiusToRaw(t))-t, 4 );
+//  }
+int16_t DallasTemperature::celsiusToRaw(float celsius) {
+
+    return static_cast<uint16_t>( celsius * 128.f );
+}
+
 // convert from raw to Fahrenheit
 float DallasTemperature::rawToFahrenheit(int16_t raw) {
 

DallasTemperature.h

@@ -158,7 +158,9 @@ class DallasTemperature {
 	// Is a conversion complete on the wire? Only applies to the first sensor on the wire.
 	bool isConversionComplete(void);
 
-  int16_t millisToWaitForConversion(uint8_t);
+  static uint16_t millisToWaitForConversion(uint8_t);
+  
+  uint16_t millisToWaitForConversion();
 
   // Sends command to one device to save values from scratchpad to EEPROM by index
   // Returns true if no errors were encountered, false indicates failure
@@ -244,6 +246,9 @@ class DallasTemperature {
 	// convert from raw to Celsius
 	static float rawToCelsius(int16_t);
 
+    // convert from Celsius to raw
+	static int16_t celsiusToRaw(float);
+
 	// convert from raw to Fahrenheit
 	static float rawToFahrenheit(int16_t);