The HDC1000 is a digital humidity sensor with integrated temperature sensor that provides excellent measurement accuracy at very low power. The device measures humidity based on a novel capacitive sensor. The humidity and temperature sensors are factory calibrated. It is functional within the full -40°C to +125°C temperature range.

In this tutorial the interfacing of the HDC1000 sensor module with particle photon has been illustrated. To read the temperature and humidity values, we have used particle with an I2c adapter.This I2C adapter makes the connection to the sensor module easy and more reliable.

Step 1: Hardware Required:

The materials that we need for accomplishing our goal includes the following hardware components:

1. HDC1000

2. Particle Photon

3. I2C Cable

4. I2C Shield for particle photon

Step 2: Hardware Hookup:

The hardware hookup section basically explains the wiring connections required between the sensor and the particle photon. Ensuring correct connections is the basic necessity while working on any system for the desired output. So, the requisite connections are as follows:

The HDC1000 will work over I2C . Here is the example wiring diagram, demonstrating how to wire up each interface of the sensor.

Out-of-the-box, the board is configured for an I2C interface, as such we recommend using this hookup if you’re otherwise agnostic.

All you need is four wires! Only four connections are required Vcc, Gnd, SCL and SDA pins and these are connected with the help of I2C cable.

These connections are demonstrated in the pictures above.

Step 3: Code for Temperature and Humidity Measurement:

Let's start with the particle code now.

While using the sensor module with the particle, we include application.h and spark_wiring_i2c.h library. "application.h" and spark_wiring_i2c.h library contains the functions which facilitate the i2c communication between the sensor and the particle.

The entire particle code is given below for the convenience of the user:

<p>#include<application.h> </p><p>#include<spark_wiring_i2c.h> </p><p>// HDC1000 I2C address is 0x40(64)</p><p>#define Addr 0x40</p><p>double cTemp = 0.0, fTemp = 0.0, humidity = 0.0;</p><p>int temp = 0, hum = 0;</p><p>void setup()</p><p>{  </p><p>// Set variable  </p><p>Particle.variable("i2cdevice", "HDC1000");  </p><p>Particle.variable("humidity", humidity);  </p><p>Particle.variable("cTemp", cTemp);</p><p>// Initialise I2C communication  </p><p>Wire.begin();  </p><p>// Initialise Serial Communication, set baud rate = 9600  </p><p>Serial.begin(9600);</p><p>// Start I2C Transmission  </p><p>Wire.beginTransmission(Addr);  </p><p>// Select configuration register  </p><p>Wire.write(0x02);  </p><p>// Temperature, humidity enabled, resolultion = 14-bits, heater on  </p><p>Wire.write(0x30);  </p><p>// Stop I2C Transmission  </p><p>Wire.endTransmission();  </p><p>delay(300);</p><p>}</p><p>void loop()</p><p>{  </p><p>unsigned int data[2];</p><p>// Start I2C Transmission  </p><p>Wire.beginTransmission(Addr);  </p><p>// Send temp measurement command  </p><p>Wire.write(0x00);  </p><p>// Stop I2C Transmission  </p><p>Wire.endTransmission();  </p><p>delay(500);</p><p>// Request 2 bytes of data  </p><p>Wire.requestFrom(Addr, 2);</p><p>// Read 2 bytes of data  </p><p>// temp msb, temp lsb  </p><p>if (Wire.available() == 2)  </p><p>{    </p><p>data[0] = Wire.read();    </p><p>data[1] = Wire.read();  </p><p>}</p><p>// Convert the data  </p><p>temp = ((data[0] * 256) + data[1]);  </p><p>cTemp = (temp / 65536.0) * 165.0 - 40;  </p><p>fTemp = cTemp * 1.8 + 32;</p><p>// Start I2C Transmission  </p><p>Wire.beginTransmission(Addr);  </p><p>// Send humidity measurement command  </p><p>Wire.write(0x01);  </p><p>// Stop I2C Transmission  </p><p>Wire.endTransmission();  </p><p>delay(500);</p><p>// Request 2 bytes of data  </p><p>Wire.requestFrom(Addr, 2);</p><p>// Read 2 bytes of data  </p><p>// temp msb, temp lsb  </p><p>if (Wire.available() == 2)  </p><p>{    </p><p>data[0] = Wire.read();    </p><p>data[1] = Wire.read();  </p><p>}</p><p>// Convert the data  </p><p>hum = ((data[0] * 256) + data[1]);  </p><p>humidity = (hum / 65536.0) * 100.0;</p><p>// Output data to dashboard  </p><p>Particle.publish("Relative Humidity : ", String(humidity));  </p><p>delay(1000);  </p><p>Particle.publish("Temperature in Celsius : ", String(cTemp));  </p><p>delay(1000);  </p><p>Particle.publish("Temperature in Fahrenheit : ", String(fTemp));  </p><p>delay(1000);</p><p>}</p>

Particle.variable() function creates the variables to store the output of the sensor and Particle.publish() function displays the output on the dashboard of the site.

The sensor output is shown in the picture above for your reference.

Step 4: Applications:

HDC1000 can be employed in heating, ventilation and air conditioning (HVAC), Smart Thermostats and Room Monitors. This sensor also finds its application in Printers, Handheld Meters,Medical Devices,Cargo Shipping as well as Automotive Windshield Defog.