humidity sensor

The SHT2x series consists of a low-cost version with the SHT20 humidity sensor. the SHT2x provides calibrated, linearized sensor signals in digital, I2C format. The SHT2x humidity sensor series contains a capacitive-type humidity sensor, a band-gap temperature sensor, and specialized analog and digital integrated circuits – all on a single CMOSens® chip. This yields superior sensor performance in terms of accuracy and stability as well as minimal power consumption.

Every sensor is individually calibrated and tested. Furthermore, the resolution of the SHT2x humidity sensor can be changed on command (8/12 bit up to 12/14 bit for RH/T) and a checksum helps to improve communication reliability.

Parts List

Schematics/Layout

I couldnt find an exact part in fritzing

microbit and SHT20

Code

Again we use a library – https://github.com/DFRobot/DFRobot_SHT20

[codesyntax lang=”cpp”]

#include <Wire.h>
#include "DFRobot_SHT20.h"

DFRobot_SHT20    sht20;

void setup()
{
    Serial.begin(9600);
    Serial.println("SHT20 Example!");
    sht20.initSHT20();                                  // Init SHT20 Sensor
    delay(100);
    sht20.checkSHT20();                                 // Check SHT20 Sensor
}

void loop()
{
    float humd = sht20.readHumidity();                  // Read Humidity
    float temp = sht20.readTemperature();               // Read Temperature
    Serial.print("Time:");
    Serial.print(millis());
    Serial.print(" Temperature:");
    Serial.print(temp, 1);
    Serial.print("C");
    Serial.print(" Humidity:");
    Serial.print(humd, 1);
    Serial.print("%");
    Serial.println();
    delay(1000);
}

[/codesyntax]

Output

Open the serial monitor – this is what I saw

Time:136805 Temperature:22.2C Humidity:46.7%
Time:137953 Temperature:23.1C Humidity:46.8%
Time:139101 Temperature:24.5C Humidity:51.7%
Time:140249 Temperature:25.2C Humidity:58.0%
Time:141397 Temperature:25.5C Humidity:62.6%
Time:142545 Temperature:25.8C Humidity:65.6%
Time:143693 Temperature:26.0C Humidity:67.6%
Time:144841 Temperature:26.1C Humidity:69.0%

Links

Sensirion_Humidity_Sensors_SHT20_Datasheet.pdf

The SHT1x digital humidity sensor is a reflow solderable sensor. The SHT1x series consists of a low-cost version with the SHT10 humidity sensor, a standard version with the SHT11 humidity sensor, and a high-end version with the SHT15 humidity sensor. As with every other Sensirion sensor type from the SHTxx humidity sensor family, they are fully calibrated and provide a digital output.

The humidity sensors are seamlessly coupled to a 14-bit-analog-to-digital converter and a serial interface circuit. This results in superior signal quality, a fast response time, and insensitivity to external disturbances (EMC).

One thing to note is that these sensors have been effectively replaced by others in sensirion’s range such as the SHT31 but they are still usable and for the hobbyist

Layout

Code

You need to install the library from – https://github.com/practicalarduino/SHT1x

This is the built in example

[codesyntax lang="cpp"]

#include <SHT1x.h>

// Specify data and clock connections and instantiate SHT1x object
#define dataPin 3
#define clockPin 4
SHT1x sht1x(dataPin, clockPin);

void setup()
{
 Serial.begin(38400); // Open serial connection to report values to host
 Serial.println("Starting up");
}

void loop()
{
 float temp_c;
 float temp_f;
 float humidity;

 // Read values from the sensor
 temp_c = sht1x.readTemperatureC();
 temp_f = sht1x.readTemperatureF();
 humidity = sht1x.readHumidity();

 // Print the values to the serial port
 Serial.print("Temperature: ");
 Serial.print(temp_c, DEC);
 Serial.print("C / ");
 Serial.print(temp_f, DEC);
 Serial.print("F. Humidity: ");
 Serial.print(humidity);
 Serial.println("%");

 delay(2000);
}

[/codesyntax]

Testing

Open the serial monitor , all going well you should see something like this

Temperature: 25.5599994659C / 78.1159973145F. Humidity: 49.05%
Temperature: 26.1399993896C / 79.1599960327F. Humidity: 50.94%
Temperature: 28.5199985504C / 83.6599960327F. Humidity: 68.56%
Temperature: 30.2299976349C / 86.6119918823F. Humidity: 75.35%
Temperature: 31.2499980927C / 88.3939971924F. Humidity: 77.40%

Links

SHT31 is the next generation of Sensirion’s temperature and humidity sensors. It builds on a new CMOSens® sensor chip that is at the heart of Sensirion’s new humidity and temperatureplatform.

The SHT3x-DIS has increased intelligence, reliability and improved accuracy specifications compared to its predecessor. Its functionality includes enhanced signal processing, two distinctive and user selectable I2C addresses and communication speeds of up to 1 MHz. The DFN package has a footprint of 2.5 x 2.5 mm2 while keeping a height of 0.9 mm.

This allows for integration of the SHT3x-DIS into a great variety of applications.

Features

Fully calibrated, linearized, and temperature compensated digital output
Wide supply voltage range, from 2.4 V to 5.5 V
I2C Interface with communication speeds up to 1 MHz and two user selectable addresses

I bought the following module

If you’re using an Wemos simply connect the VIN pin to the 3v3 voltage pin, GND to ground, SCL to I2C Clock (D1) and SDA to I2C Data (D2).

Here is a layout drawn up in fritzing to illustrate this

Layout

microbit and sht31

Code

This example uses the adafruit sht31 library – https://github.com/adafruit/Adafruit_SHT31

[codesyntax lang=”cpp”]

#include <Arduino.h>
#include <Wire.h>
#include "Adafruit_SHT31.h"

Adafruit_SHT31 sht31 = Adafruit_SHT31();


void setup() 
{
  Serial.begin(9600);
  if (! sht31.begin(0x44)) 
  {
    Serial.println("Couldn't find SHT31");
    while (1) delay(1);
  }
}


void loop() 
{
  float t = sht31.readTemperature();
  float h = sht31.readHumidity();

  if (! isnan(t)) 
  {
    Serial.print("Temp *C = "); Serial.println(t);
  } 
  else 
  { 
    Serial.println("Failed to read temperature");
  }
  
  if (! isnan(h)) 
  {
    Serial.print("Hum. % = "); Serial.println(h);
  } 
  else 
  { 
    Serial.println("Failed to read humidity");
  }
  Serial.println();
  delay(1000);
}

[/codesyntax]

Output

Open the serial monitor window

Temp *C = 27.27
Hum. % = 32.90

Temp *C = 27.01
Hum. % = 32.20

Temp *C = 26.76
Hum. % = 31.83

Temp *C = 26.52
Hum. % = 31.79

Temp *C = 26.30
Hum. % = 31.91

Link

1PCS/LOT SHT31 Temperature & SHT31-D Humidity Sensor module Breakout Weather for Arduino