SHT85 with Arduino

Temperature and humidity monitoring is a common thing in many projects.

normally we are using DHT11/22 for normal prototype building. But it has some limitations in the sense of some product building.

For DHT 11 :

• Ultra low cost
• 3 to 5V power and I/O
• 2.5mA max current use during conversion (while requesting data)
• Good for 20-80% humidity readings with 5% accuracy
• Good for 0-50°C temperature readings ±2°C accuracy
• No more than 1 Hz sampling rate (once every second)
• Body size 15.5mm x 12mm x 5.5mm
• 4 pins with 0.1" spacing

For DHT 22:

• Low cost
• 3 to 5V power and I/O
• 2.5mA max current use during conversion (while requesting data)
• Good for 0-100% humidity readings with 2-5% accuracy
• Good for -40 to 80°C temperature readings ±0.5°C accuracy
• No more than 0.5 Hz sampling rate (once every 2 seconds)
• Body size 15.1mm x 25mm x 7.7mm
• 4 pins with 0.1" spacing

But sometimes we need accuracy more than these sensors. at that time the good option is SHT85 sensor by Sensirion.

• Humidity Range: 0% to 100% Relative Humidity
• Humidity Accuracy: ± 1.5% RH
• Temperature Accuracy: ± 0.1°C
• RH Response Time: 8s
• Temperature Response Time: 2s
• Sensor Interface Type: I2C
• Sensor Case Style: SIP
• No. of Pins: 4Pins
• Operating Temperature Min: -40°C
• Operating Temperature Max: 105°C
• Supply Voltage : 2.15V - 5.5V

Here sensor interface using I2C. So follow below connection diagram.

For SDA and SCL pin config:

Board:I2C / TWI pins

Uno, Ethernet A4 (SDA), A5 (SCL)

Mega2560 20 (SDA), 21 (SCL)

Leonardo 2 (SDA), 3 (SCL)

Due 20 (SDA), 21 (SCL), SDA1, SCL1

Here I'm using Arduino Uno.

After connecting setup library and upload code.

To get SHT library Goto to this link Download as zip >> ADD library as a zip in Arduino IDE.

Then:

• Import the Wire library like this: From the menu bar, select Sketch > Import Library > Wire
• Import the arduino-sht library: From the menu bar, select Sketch > Import Library > arduino-sht
• Create an instance of the SHTSensor class (SHTSensor sht;)
• In setup(), make sure to init the Wire library with Wire.begin()
• If you want to use the serial console, remember to initialize the Serial library with Serial.begin(9600)
• Call sht.readSample() in the loop() function, which reads a temperature and humidity sample from the sensor
• Use sht.getHumidity() and sht.getTemperature() to get the values from the last sample

Upload Example sketch to get Temperature and Humidity :

#include <Wire.h>
#include "SHTSensor.h"
SHTSensor sht;
// To use a specific sensor instead of probing the bus use this command:
// SHTSensor sht(SHTSensor::SHT3X);
void setup() {
// put your setup code here, to run once:
Wire.begin();
Serial.begin(9600);
delay(1000); // let serial console settle
if (sht.init()) {
Serial.print("init(): success\n");
} else {
Serial.print("init(): failed\n");
}
sht.setAccuracy(SHTSensor::SHT_ACCURACY_MEDIUM); // only supported by SHT3x
}
void loop() {
// put your main code here, to run repeatedly:
if (sht.readSample()) {
Serial.print("SHT:\n");
Serial.print("  RH: ");
Serial.print(sht.getHumidity(), 2);
Serial.print("\n");
Serial.print("  T:  ");
Serial.print(sht.getTemperature(), 2);
Serial.print("\n");
} else {
Serial.print("Error in readSample()\n");
}
delay(1000);
}

Then view your result via Serial Monitor;

Credits : https://github.com/Sensirion/arduino-sht