Raspberry Pi and SHT31 humidity sensor java example
In this example we will connect an SHT31 humidity sensor to a Raspberry Pi and use Java to display the temperature readings, there are other languages such as C and python which work as well but I wanted to try something a little different
The new digital SHT3x humidity sensor series takes sensor technology to a new level. As the successor of the SHT2x series it is determined to set the next industry standard in humidity sensing. The SHT3x humidity sensor series consists of a low-cost version with the SHT30 humidity sensor, a standard version with the SHT31 humidity sensor, and a high-end version with the SHT35 humidity sensor. The SHT3x humidity sensor series combines multiple functions and various interfaces (I2C, analog voltage output) with a applications-friendly, very wide operating voltage range (2.4 to 5.5 V). The SHT3x humidity sensor is available in both large and small volumes.
The SHT3x builds on a completely new and optimized CMOSens® chip, which allows for increased reliability and improved accuracy specifications. The SHT3x offers a range of new features, such as enhanced signal processing, two distinctive and user-selectable I2C addresses, an alert mode with programmable humidity and temperature limits, and communication speeds of up to 1 MHz.
You can read more – https://www.sensirion.com/en/environmental-sensors/humidity-sensors/digital-humidity-sensors-for-various-applications/
Parts List
Label | Part Type | |
---|---|---|
Part2 | Adafruit SHT31-D Sensirion Temperature/Humidity Sensor | |
Raspberry Pi1 | Raspberry Pi 2 |
Layout
Code
This time we explore the world of Java on the Raspberry Pi
First you need to install PI4j – http://pi4j.com/install.html . I’ll sum it up as its easy to install from a terminal
The simplest method to install Pi4J on your RaspberryPi is to execute the following command directly on your RaspberryPi.
curl -s get.pi4j.com | sudo bash
Now for the java code – this is courtesy of a controleverything example
[codesyntax lang=”java”]
// Distributed with a free-will license. // Use it any way you want, profit or free, provided it fits in the licenses of its associated works. // SHT31 // This code is designed to work with the SHT31_I2CS I2C Mini Module available from ControlEverything.com. // https://www.controleverything.com/content/Humidity?sku=SHT31_I2CS#tabs-0-product_tabset-2 import com.pi4j.io.i2c.I2CBus; import com.pi4j.io.i2c.I2CDevice; import com.pi4j.io.i2c.I2CFactory; import java.io.IOException; public class SHT31 { public static void main(String args[]) throws Exception { // Create I2CBus I2CBus bus = I2CFactory.getInstance(I2CBus.BUS_1); // Get I2C device, SHT31 I2C address is 0x44(68) I2CDevice device = bus.getDevice(0x44); // Send high repeatability measurement command // Command msb, command lsb byte[] config = new byte[2]; config[0] = (byte)0x2C; config[1] = (byte)0x06; device.write(config, 0, 2); Thread.sleep(500); // Read 6 bytes of data // temp msb, temp lsb, temp CRC, humidity msb, humidity lsb, humidity CRC byte[] data = new byte[6]; device.read(data, 0, 6); //Convert the data double cTemp = ((((data[0] & 0xFF) * 256) + (data[1] & 0xFF)) * 175.0) / 65535.0 - 45.0; double fTemp = ((((data[0] & 0xFF) * 256) + (data[1] & 0xFF)) * 315.0) / 65535.0 - 49.0; double humidity = ((((data[3] & 0xFF) * 256) + (data[4] & 0xFF)) * 100.0) / 65535.0; //Output data to screen System.out.printf("Temperature in Celsius : %.2f C %n", cTemp); System.out.printf("Temperature in Fahrenheit : %.2f F %n", fTemp); System.out.printf("Relative Humidity is : %.2f %%RH %n", humidity); } }
[/codesyntax]
Now you have to compile and run the program like this
$> sudo pi4j SHT31.java
Testing
You should see the following
Links
1PCS/LOT SHT31 Temperature & SHT31-D Humidity Sensor module Breakout Weather for Arduino