Add function to get temperature to DS3231

Read temperature from register 0x11 of DS3231
Change the example accordingly

RTClib.cpp

@@ -504,3 +504,22 @@ void RTC_DS3231::writeSqwPinMode(Ds3231SqwPinMode mode) {
 
   //Serial.println( read_i2c_register(DS3231_ADDRESS, DS3231_CONTROL), HEX);
 }
+
+float RTC_DS3231::getTemperature()
+{
+  uint8_t msb, lsb;
+  Wire.beginTransmission(DS3231_ADDRESS);
+  Wire._I2C_WRITE(DS3231_TEMPERATUREREG);
+  Wire.endTransmission();
+  
+  Wire.requestFrom(DS3231_ADDRESS, 2);
+  msb = Wire._I2C_READ();
+  lsb = Wire._I2C_READ();
+  
+//  Serial.print("msb=");
+//  Serial.print(msb,HEX);
+//  Serial.print(", lsb=");
+//  Serial.println(lsb,HEX);
+
+  return (float) msb + (lsb >> 6) * 0.25f;
+}

RTClib.h

@@ -19,6 +19,7 @@ class TimeSpan;
 #define DS3231_ADDRESS  0x68
 #define DS3231_CONTROL  0x0E
 #define DS3231_STATUSREG 0x0F
+#define DS3231_TEMPERATUREREG	0x11
 
 #define SECONDS_PER_DAY 86400L
 
@@ -103,6 +104,7 @@ public:
     static DateTime now();
     static Ds3231SqwPinMode readSqwPinMode();
     static void writeSqwPinMode(Ds3231SqwPinMode mode);
+	static float getTemperature();		// in Celcius degree
 };
 
 

examples/ds3231/ds3231.ino

@@ -72,6 +72,10 @@ void loop () {
     Serial.print(future.second(), DEC);
     Serial.println();
     
+    Serial.print("Temperature: ");
+    Serial.print(rtc.getTemperature());
+    Serial.println(" C");
+    
     Serial.println();
     delay(3000);
 }