sht21_logger.ino

//Webhook setup for Particle Console
/*
"event": "sensor_1",
"url": "https://api.thingspeak.com/update",
"requestType": "POST",
"form": {
		"api_key": "{{k}}",
		"field1": "{{1}}",
		"field2": "{{2}}",
		"field3": "{{3}}",
		"field4": "{{4}}",
		"field5": "{{5}}",
		"field6": "{{6}}",
		"field7": "{{7}}",
		"field8": "{{8}}",
		"lat": "{{a}}",
		"long": "{{o}}",
		"elevation": "{{e}}",
		"status": "{{s}}"
},
"mydevices": true,
"noDefaults": true
}
*/

#include "SHT2x.h"

SHT2x sht;
FuelGauge fuel;

int led = 7;

String Temp;
String Humidity;
String bat_v;
String SoC;
String Now;
String POST;
const String key = "<API_KEY>";

void setup() {
  Serial.begin(9600);
  Wire.begin();
  pinMode(D7, OUTPUT);
}

void loop() {
  Now = String(Time.now());
  Temp = String(sht.GetTemperature());
  Humidity = String(sht.GetHumidity());
	bat_v = String(fuel.getVCell());
	SoC = String(fuel.getSoC());

	String item_1 = "{ \"1\": \"" + Now + "\",";
	String item_2 = "\"2\": \"" + Temp + "\",";
	String item_3 = "\"3\": \"" + Humidity + "\",";
	String item_4 = "\"4\": \"" + bat_v + "\",";
	String item_5 = "\"5\": \"" + SoC + "\",";
	String item_k = "\"k\": \"" + key + "\" }";
	POST = item_1 + item_2 + item_3 + item_4 + item_5 + item_k;
	Serial.println(POST);
  Particle.publish("sensor_1", POST, 60, PRIVATE); // publish to cloud

	digitalWrite(D7, HIGH);
  delay(250);
  digitalWrite(D7, LOW);
  delay(750);
	for(int i = 0; i < 1; i++) {
		delay(60000);
	}

}

SHT2x.cpp

/*
  SHT2x - A Humidity Library for Arduino.

  Supported Sensor modules:
    SHT21-Breakout Module - http://www.moderndevice.com/products/sht21-humidity-sensor
  SHT2x-Breakout Module - http://www.misenso.com/products/001

  Created by Christopher Ladden at Modern Device on December 2009.
  Modified by Paul Badger March 2010

  Modified by www.misenso.com on October 2011:
  - code optimisation
  - compatibility with Arduino 1.0

  This library is free software; you can redistribute it and/or
  modify it under the terms of the GNU Lesser General Public
  License as published by the Free Software Foundation; either
  version 2.1 of the License, or (at your option) any later version.

  This library 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
  Lesser General Public License for more details.

  You should have received a copy of the GNU Lesser General Public
  License along with this library; if not, write to the Free Software
  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
*/

#include "SHT2x.h"

/******************************************************************************
 * Global Functions
 ******************************************************************************/

/**********************************************************
 * GetHumidity
 *  Gets the current humidity from the sensor.
 *
 * @return float - The relative humidity in %RH
 **********************************************************/
float SHT2x::GetHumidity(void)
{
  return (-6.0 + 125.0 / 65536.0 * (float)(readSensor(eRHumidityHoldCmd)));
}

/**********************************************************
 * GetTemperature
 *  Gets the current temperature from the sensor.
 *
 * @return float - The temperature in Deg C
 **********************************************************/
float SHT2x::GetTemperature(void)
{
  return (-46.85 + 175.72 / 65536.0 * (float)(readSensor(eTempHoldCmd)));
}


/******************************************************************************
 * Private Functions
 ******************************************************************************/

uint16_t SHT2x::readSensor(uint8_t command)
{
    uint16_t result;

    Wire.beginTransmission(eSHT2xAddress);  //begin
    Wire.write(command);          //send the pointer location
    delay(100);
    Wire.endTransmission();                 //end

    Wire.requestFrom(eSHT2xAddress, 3);
    while(Wire.available() < 3) {
      ; //wait
    }

    //Store the result
    result = ((Wire.read()) << 8);
    result += Wire.read();
  result &= ~0x0003;   // clear two low bits (status bits)
    return result;
}

SHT2x.h

/*
  SHT2x - A Humidity Library for Arduino.

  Supported Sensor modules:
    SHT21-Breakout Module - http://www.moderndevice.com/products/sht21-humidity-sensor
  SHT2x-Breakout Module - http://www.misenso.com/products/001

  Created by Christopher Ladden at Modern Device on December 2009.

  Modified by www.misenso.com on October 2011:
  - code optimisation
  - compatibility with Arduino 1.0

  This library is free software; you can redistribute it and/or
  modify it under the terms of the GNU Lesser General Public
  License as published by the Free Software Foundation; either
  version 2.1 of the License, or (at your option) any later version.

  This library 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
  Lesser General Public License for more details.

  You should have received a copy of the GNU Lesser General Public
  License along with this library; if not, write to the Free Software
  Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
*/


#ifndef SHT2X_H
#define SHT2X_H

#include <inttypes.h>
#include "application.h"
#include "math.h"

typedef enum {
    eSHT2xAddress = 0x40,
} HUM_SENSOR_T;

typedef enum {
    eTempHoldCmd    = 0xE3,
    eRHumidityHoldCmd = 0xE5,
    eTempNoHoldCmd      = 0xF3,
    eRHumidityNoHoldCmd = 0xF5,
} HUM_MEASUREMENT_CMD_T;

class SHT2x
{
  private:
  uint16_t readSensor(uint8_t command);

  public:
    float GetHumidity(void);
    float GetTemperature(void);
};

// extern SHT2xClass SHT2x;

#endif