temperature: Support htu21d controller

   node lib/temperature '{ "controller": "htu21d" }'

Change-Id: Ifadc2e9d3199d260b48e41a661762bb672ce9cd3
Origin: https://github.com/dror3go/generic-sensors-lite/commit/6727023aa6420b645451780039b326f6d17b8521.patch
Author: Dror T <[email protected]>
Relate-to: #14

lib/temperature/index.js

@@ -19,9 +19,11 @@
 
 var console = require('console');
 var BMP085 = null;
+var HTU21D = null;
 
 try {
   BMP085 = require('@abandonware/bmp085-sensor');
+  HTU21D = require('htu21d-i2c');
 } catch (err){
   // console.log(err);
 }
@@ -59,20 +61,37 @@ TemperatureSensor.prototype.update = function update() {
   var self = this;
   try {
     self.hasReading = false;
-    self.sensor.read(function (err, data) {
-      if (err) {
-        return self.onerror(err);
-      }
-      if ((data === null) || (typeof data === 'undefined')) {
-        return self.onerror("Invalid data");
-      } else {
-        self.timestamp = new Date();
-        self.celsius = Number(data.temperature);
-        self.hasReading = true;
-        self.onreading();
-        self.hasReading = false;
-      }
-    });
+    if (typeof self.sensor.readTemperature === 'function') {
+      self.sensor.readTemperature(function (err, data) {
+        if (err) {
+          return self.onerror(err);
+        }
+        if ((data === null) || (typeof data === 'undefined')) {
+          return self.onerror("Invalid data");
+        } else {
+          self.timestamp = new Date();
+          self.celsius = data;
+          self.hasReading = true;
+          self.onreading();
+          self.hasReading = false;
+        }
+      });
+    } else {
+      self.sensor.read(function (err, data) {
+        if (err) {
+          return self.onerror(err);
+        }
+        if ((data === null) || (typeof data === 'undefined')) {
+          return self.onerror("Invalid data");
+        } else {
+          self.timestamp = new Date();
+          self.celsius = Number(data.temperature);
+          self.hasReading = true;
+          self.onreading();
+          self.hasReading = false;
+        }
+      });
+    }
   } catch (err) {
     self.onerror(err);
   }
@@ -96,6 +115,11 @@ TemperatureSensor.prototype.start = function start() {
                  (this.options.controller === 'bmp180')
                 ) {
         this.sensor = new BMP085(this.options.sensor);
+      } else if ((this.options.controller === 'htu21d') ||
+                 (this.options.controller === 'node-htu21d') ||
+                 (this.options.controller === 'htu21d-i2c')
+                ) {
+        this.sensor = new HTU21D(this.options.sensor);
       } else {
         throw new Error("TODO: unsupported controller:" + this.options.controller);
       }
@@ -107,18 +131,24 @@ TemperatureSensor.prototype.start = function start() {
   }
 
   try {
-    self.sensor.calibrate(function (err /* , data*/) {
-      if (err) {
-        throw err;
-      }
-      if (!self.interval) {
-        self.interval = setInterval(function() { self.update(); },
-                                    1000. / self.options.frequency);
-        self.onactivate();
-        self.state = 'activated';
-      }
-    });
-
+    if (typeof self.sensor.calibrate !== 'function') {
+      self.interval = setInterval(function() { self.update(); },
+                                  1000. / self.options.frequency);
+      self.onactivate();
+      self.state = 'activated';
+    } else {
+      self.sensor.calibrate(function (err /* , data*/) {
+        if (err) {
+          throw err;
+        }
+        if (!self.interval) {
+          self.interval = setInterval(function() { self.update(); },
+                                      1000. / self.options.frequency);
+          self.onactivate();
+          self.state = 'activated';
+        }
+      });
+    }
   } catch(err) {
     self.onerror(err);
   }