Added HTU21 Sensor (#588)

* Added HTU21 Sensor Support

Co-authored-by: Jonathan Wells <jonathan-wells@oist.jp>

main/ZsensorHTU21.ino

@@ -0,0 +1,125 @@
+/*  
+  OpenMQTTGateway Addon  - ESP8266 or Arduino program for home automation 
+ 
+   Act as a wifi or ethernet gateway between your 433mhz/infrared IR signal  and a MQTT broker
+   Send and receiving command by MQTT
+   
+   This is the Climate Addon:
+   - Measures Temperature, Humidity and Pressure
+   - Generates Values for: Temperature in degrees C and F, Humidity in %, Pressure in Pa, Altitude in Meter and Feet
+   - Required Hardware Module: HTU21
+   - Required Library: SparkFun HTU21 Library v1.1.3
+
+   Connection Schemata:
+   --------------------
+
+   HTU21 ------> Arduino Uno ----------> ESP8266
+   ==============================================
+   Vcc ---------> 5V -------------------> Vu (5V)
+   GND ---------> GND ------------------> GND
+   SCL ---------> Pin A5 ---------------> D1
+   SDA ---------> Pin A4 ---------------> D2
+   
+    This file is part of OpenMQTTGateway.
+    
+    OpenMQTTGateway is free software: you can redistribute it and/or modify
+    it under the terms of the GNU General Public License as published by
+    the Free Software Foundation, either version 3 of the License, or
+    (at your option) any later version.
+
+    OpenMQTTGateway is distributed in the hope that it will be useful,
+    but WITHOUT ANY WARRANTY; without even the implied warranty of
+    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+    GNU General Public License for more details.
+
+    You should have received a copy of the GNU General Public License
+    along with this program.  If not, see <http://www.gnu.org/licenses/>.
+*/
+#include "User_config.h"
+
+#ifdef ZsensorHTU21
+#include "Wire.h" // Library for communication with I2C / TWI devices
+#include <stdint.h>
+#include "SparkFunHTU21D.h"
+#include "config_HTU21.h"
+
+//Time used to wait for an interval before resending measured values
+unsigned long timehtu21 = 0;
+
+//Global sensor object
+HTU21D htuSensor;
+
+void setupZsensorHTU21()
+{
+  delay(10); // Gives the Sensor enough time to turn on
+  Log.notice(F("HTU21 Initialized - begin()" CR));
+
+#if defined(ESP32)
+  Wire.begin(I2C_SDA, I2C_SCL);
+  htuSensor.begin(Wire);
+#else
+#endif
+  htuSensor.begin();
+}
+
+void MeasureTempHum()
+{
+
+  if (millis() > (timehtu21 + TimeBetweenReadinghtu21))
+  {
+    Log.trace(F("Read HTU21 Sensor" CR));
+
+    timehtu21 = millis();
+    static float persisted_htu_tempc;
+    static float persisted_htu_hum;
+
+    float HtuTempC = htuSensor.readTemperature();
+    float HtuHum = htuSensor.readHumidity();
+
+    if (HtuTempC >= 998 || HtuHum >= 998 )
+    {
+      Log.error(F("Failed to read from sensor HTU21!" CR));
+      return;
+    }
+
+    // Check if reads failed and exit early (to try again).
+    if (isnan(HtuTempC) || isnan(HtuHum))
+    {
+      Log.error(F("Failed to read from sensor HTU21!" CR));
+    }
+    else
+    {
+      Log.notice(F("Creating HTU21 buffer" CR));
+      StaticJsonBuffer<JSON_MSG_BUFFER> jsonBuffer;
+      JsonObject &HTU21data = jsonBuffer.createObject();
+      // Generate Temperature in degrees C
+      if (HtuTempC != persisted_htu_tempc || htu21_always)
+      {
+        float HtuTempF = (HtuTempC*1.8)+32;
+        HTU21data.set("tempc", (float)HtuTempC);
+        HTU21data.set("tempf", (float)HtuTempF);
+      }
+      else
+      {
+        Log.notice(F("Same Temp. Don't send it" CR));
+      }
+
+      // Generate Humidity in percent
+      if (HtuHum != persisted_htu_hum || htu21_always)
+      {
+        HTU21data.set("hum", (float)HtuHum);
+      }
+      else
+      {
+        Log.notice(F("Same Humidity. Don't send it" CR));
+      }
+
+      if (HTU21data.size() > 0)
+        pub(HTUTOPIC, HTU21data);
+    }
+    persisted_htu_tempc = HtuTempC;
+    persisted_htu_hum = HtuHum;
+  }
+}
+
+#endif