Difference between revisions of "SHT31 Temperature and Humidity Sensor"

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((2) Period Measurement)
(Demo for Arduino)
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=='''Demo for Arduino'''==
 
=='''Demo for Arduino'''==
 
+
Demo code: [[Media:SHT3x-arduino-demo.zip]]
 
===(1) Single Measurement===
 
===(1) Single Measurement===
 
In single measurement mode, the sensor collects data every time the controller board sends out the data collecting command. The power consumption could be very low in this mode since users can read data according to their needs.
 
In single measurement mode, the sensor collects data every time the controller board sends out the data collecting command. The power consumption could be very low in this mode since users can read data according to their needs.

Revision as of 02:56, 31 July 2020

Introduction

SHT31-DIS-F digital temperature and humidity sensor is based upon the Sensirion SHT31-F sensor IC. Thanks to Sensirion’s CMOSens® technology, highly integrated capacitive humidity sensing components and band-gap temperature sensing components, the SHT31-F offers high reliability and long-term stability with low power consumption, fast response and strong anti-interference ability. The sensor supports I2C communication, and is compatible with 3.3V/5V controllers like Arduino, micro:bit, ESP32. It is easy to achieve precise and high-reliability temperature and humidity sensing for urban environment monitoring, intelligent buildings, industrial automation, smart home and other Internet of Things applications.

SHT31-DIS-F is the standard version of the SHT3x series. It provides humidity accuracy Plus/Minus 2% RH @ 0%RH to 100%RH (at 25 Degree Celsius), and temperature accuracy Plus/Minus 0.2 Degree Celsius @ 0 Degree Celsius to 90 Degree Celsius (typical).

The SHT31-DIS-F chip features a PTFE membrane dedicated to protecting the sensor opening from liquids and dust according to IP67. It thus allows the sensor to work under harsh environmental conditions, where spray water and high exposure to dust might be challenging for accurate sensor performance. Due to minimal package volume and the membrane’s high water vapor permeability, the response time of the relative humidity and temperature signal is identical to the value achieved by the uncovered sensor. Although the membrane option provides perfect protection against water and dust ingress, it does not in general prevent contamination from volatile chemicals.


Features

  • Onboard SHT31-DIS-F chip, IP67 dust-proof protective film.
  • Compatible with 3.3V/5V controllers, Compatible with Raspberry Pi/Arduino Motherboard.
  • Ocean: 22AWG environmentally friendly high temperature resistant silicone wire, JST-PA 2.0mm 4-Pin to DuPont female single head, wire length 210mm.
  • High precise, internal auto-calibrated, digital output, Low power consumption, fast response, and strong anti-interference.

Applications

  • Smart buildings, Furniture
  • Weather Station
  • Warehouse Storage
  • Animal and Plant Breeding
  • Animal Incubator
  • Plant Seed Germination Box

Product Size

SHT31 Temperature and Humidity Sensor-73.jpg
SHT31 Temperature and Humidity Sensor-74.jpg

Pin and DIP Switch Description

SHT31 Temperature and Humidity Sensor-75.jpg

Connection Diagram

Connect to Arduino:

  • Note: Do not connect the DuPont female single-head wire directly to the UNO R3 control board. You need to stack the sensor expansion board on the UNO R3 control board or connect the male-to-male Dupont wire on the Dupont female single-head wiring(bread wire).
  • We connected the 4pin interface of the sensor to the UNO R3 control board in the experiment.
  • Dial the DIP switch to 0X45
SHT31 Temperature and Humidity Sensor-71.jpg

Connect to Raspberry Pi:

  • We connected the 4pin interface of the sensor to the Raspberry Pi 4B control board in the experiment.
  • Dial the DIP switch to 0X44
SHT31 Temperature and Humidity Sensor-72.jpg

Specifications

Sensor Specifications

  • Operating Voltage: 2.15V to 5.5V
  • Operating Current: Less Than 1.5mA
  • Humidity Detection Range: 0%RH to 100%RH
  • Humidity Accuracy: Plus/Minus 2%RH@0%RH to 100%RH(at 25 Degree Celsius)
  • Temperature Detection Range: -40 Degree Celsius to 125 Degree Celsius
  • Temperature Accuracy: Plus/Minus 0.2 Degree Celsius @0 Degree Celsius to 90 Degree Celsius (Typical)
  • Communication: I2C (JST PA SMT 4-Pin interface to 2.54mm pitch pin header interface)
  • Outline Dimension: 22.36mm * 31.35mm
  • Mounting Hole Size: 3mm
  • Mounting Hole Pitch: 15mm

Ocean Wire Specifications

  • Cable Specifications: 22AWG
  • Material: Silicone
  • Withstand Voltage: Less Than 50V
  • Withstand Current: Less Than 1000MA
  • Length: 21cm
  • Line Sequence: Black negative power supply, Red positive power supply, Green-SDA, Blue-SDA

Demo for Arduino

Demo code: Media:SHT3x-arduino-demo.zip

(1) Single Measurement

In single measurement mode, the sensor collects data every time the controller board sends out the data collecting command. The power consumption could be very low in this mode since users can read data according to their needs.

/*!
 * @brief Construct the function
 * @param pWire IIC bus pointer object and construction device, can both pass or not pass parameters, Wire in default.
 * @param address Chip IIC address, two optional addresse.
*/
/*!
 * @file singleMeasurement.ino
 * @brief Read ambient temperature (C/F) and relative humidity (%RH) in single-read mode.
 * @n Experimental phenomenon: the chip defaults in this mode, we need to send instructions to enable the chip collect data,
 * which means the repeatability of the read needs to be set (the difference between the data measured by the chip under the same measurement conditions)
 * then read the temperature and humidity data and print the data in the serial port.
 * @n Single measure mode: read data as needed, power consumption is relatively low, the chip idle state only costs 0.5mA. 
*/
#include <SHT3x.h>
/*!
 * @brief Construct the function
 * @param pWire IIC bus pointer object and construction device, both can pass or not pass parameters, 
 * Wire in default.
 * @param address Chip IIC address, two optional addresses 0x44 and 0x45(0x45 in default).
 * @param RST RST Chip reset pin, 4 in default.
 * @n IIC address is determined by the pin addr on the chip.
 * @n When the ADR is connected to VDD, the chip IIC address is 0x45.
 * @n When the ADR is connected to GND, the chip IIC address is 0x44.
 */
//SHT3x sht3x(&Wire,/*address=*/0x45,/*RST=*/4);
SHT3x   sht3x;
void setup() {
	Serial.begin(9600);
	//Initialize the chip
	while (sht3x.begin() != 0) {
		Serial.println("Failed to Initialize the chip, please confirm the wire connection");
		delay(1000);
	}
	/**
   * readSerialNumber Read the serial number of the chip.
   * @return Return 32-digit serial number.
   */
	Serial.print("Chip serial number");
	Serial.println(sht3x.readSerialNumber());
	/**
   * softReset Send command resets via IIC, enter the chip's default mode single-measure mode, 
   * turn off the heater, and clear the alert of the ALERT pin.
   * @return Read the register status to determine whether the command was executed successfully, 
   * and return true indicates success.
   */
	if(!sht3x.softReset()) {
		Serial.println("Failed to Initialize the chip....");
	}
	/**
   * heaterEnable(): Turn on the heater inside the chip to enable the sensor get correct humidity value in wet environments.
   * @return Read the status of the register to determine whether the command was executed successfully,
   * and return true indicates success.
   * @note Heaters should be used in wet environments, and other cases of use will result in incorrect readings
   */
	//if(!sht3x.heaterEnable()){
	// Serial.println("Failed to turn on the heater....");
	//}
	Serial.println("------------------Read adta in single measurement mode-----------------------");
}
void loop() {
	Serial.print("Ambient Temperature(°C/F):");
	/**
   * getTemperatureC Get the meansured temperature(℃).
   * @return Return float temperature data.
   */
	Serial.print(sht3x.getTemperatureC());
	Serial.print(" C/");
	/**
   * getTemperatureF:Get the meansured temperature(℉).
   * @return Return float temperature data.
   */
	Serial.print(sht3x.getTemperatureF());
	Serial.print(" F ");
	Serial.print("Relative Humidity(%RH):");
	/**
   * getHumidityRH: Get the meansured humidity (%RH)
   * @return Return float humidity data
   */
	Serial.print(sht3x.getHumidityRH());
	Serial.println(" %RH");
	/**
   * @brief Get temperature and humidity data in single measurement mode.
   * @param repeatability Set repeatability to read temperature and humidity data with the type eRepeatability_t.
   * @note  Optional parameters:
               eRepeatability_High /**In high repeatability mode, the humidity repeatability is 0.10%RH, the temperature repeatability is 0.06°C
               eRepeatability_Medium,/**In medium repeatability mode, the humidity repeatability is 0.15%RH, the temperature repeatability is 0.12°C.
               eRepeatability_Low, /**In low repeatability mode, the humidity repeatability is0.25%RH, the temperature repeatability is 0.24°C
   * @return Return a structure containing celsius temperature (°C), Fahrenheit temperature (°F), relative humidity(%RH), status code.
   * @n Return O indicates right data return.
  SHT3x::sRHAndTemp_t data = sht3x.readTemperatureAndHumidity(sht3x.eRepeatability_High);
  if(data.ERR == 0){
    Serial.print("Ambient Temperature(°C/F):");
    Serial.print(data.TemperatureC);
    Serial.print(" C/");
    Serial.print(data.TemperatureF);
    Serial.print(" F ");
    Serial.print("Relative Humidity(%RH):");
    Serial.print(data.Humidity);
    Serial.println(" %RH");
  }
  */
	delay(1000);
}

Test Methods and Results

Print out the temperature and humidity information from the serial port.

Sht31-single.png

(2) Period Measurement

In period measurement mode, the sensor collects data at the user-set frequency.

#include <SHT3x.h>
/*!
 * @brief Construct the function
 * @param pWire IIC bus pointer object and construction device, can both pass or not pass parameters, Wire in default.
 * @param address Chip IIC address, two optional addresses 0x44 and 0x45(0x45 in default).
 * @param RST Chip reset pin, 4 in default.
 * @n The IIC address is determined by the pin addr on the chip.
 * @n When the ADR is connected to VDD, the chip IIC address is 0x45.
 * @n When the ADR is connected to GND, the chip IIC address is 0x44.
 */
//SHT3x sht3x(&Wire,/*address=*/0x45,/*RST=*/4);
SHT3x sht3x;
void setup() {
	Serial.begin(9600);
	//Initialize the chip to detect if it can communicate properly.
	while (sht3x.begin() != 0) {
		Serial.println("Failed to initialize the chip, please confirm the chip connection");
		delay(1000);
	}
	/**
   * readSerialNumber Read the serial number of the chip
   * @return Return 32-digit serial number
   */
	Serial.print("chip serial number: ");
	Serial.println(sht3x.readSerialNumber());
	/**
   * softReset Send command resets via IIC, enter the chip's default mode single-measure mode, 
   * turn off the heater, and clear the alert of the ALERT pin.
   * @return Read the status register to determine whether the command was executed successfully, 
   * and return true indicates success.
   */
	if(!sht3x.softReset()) {
		Serial.println("Failed to reset the chip");
	}
	/**
   * pinReset Reset through the chip's reset pin, enter the chip's default mode single-measure mode, 
   * turn off the heater, and clear the alert of the ALERT pin.
   * @return The status register has a data bit that detects whether the chip has been reset, 
   * and return true indicates success.
   * @note When using this API, the reset pin of the chip nRESET should be connected to RST (default to pin4) of arduino.
   */
	//if(!sht3x.pinReset()){
	//Serial.println("Failed to reset the chip");
	//}
	/**
   * heaterEnable() Turn on the heater inside the chip so that the sensor can have accurate humidity data even in humid environment.
   * @return Read the status register to determine whether the command was executed successfully, and return true indicates success.
   * @NOTE Heaters should be used in wet environment, and other cases of use will result in incorrect readings.
   */
	//if(!sht3x.heaterEnable()){
	// Serial.println("Failed to turn on the heater");
	//}
	/**
   * startPeriodicMode Enter cycle measurement mode and set repeatability and read frequency.
   * @param measureFreq Read the eMeasureFrequency_t data frequency.
   * @note  Selectable parameters:
               eMeasureFreq_Hz5,   /**the chip collects data in every 2s
               eMeasureFreq_1Hz,   /**the chip collects data in every 1s 
               eMeasureFreq_2Hz,   /**the chip collects data in every 0.5s 
               eMeasureFreq_4Hz,   /**the chip collects data in every 0.25s 
               eMeasureFreq_10Hz   /**the chip collects data in every 0.1s 
   * @param repeatability Read the repeatability of temperature and humidity data, the default parameter is eRepeatability_High.
   * @note  Optional parameters:
               eRepeatability_High /**In high repeatability mode, the humidity repeatability is 0.10%RH, the temperature repeatability is 0.06°C
               eRepeatability_Medium,/**In medium repeatability mode, the humidity repeatability is 0.15%RH, the temperature repeatability is 0.12°C.
               eRepeatability_Low, /**In low repeatability mode, the humidity repeatability is0.25%RH, the temperature repeatability is 0.24°C
   * @return Read the status of the register to determine whether the command was executed successfully, and return true indicates success
   */
	if(!sht3x.startPeriodicMode(sht3x.eMeasureFreq_1Hz)) {
		Serial.println("Failed to enter the periodic mode");
	}
	Serial.println("------------------Read data in cycle measurement mode-----------------------");
}
void loop() {
	Serial.print("Ambient temperature(°C/F):");
	/**
   * getTemperatureC Get the measured temperature (in degrees Celsius).
   * @return Return the float temperature data.
   */
	Serial.print(sht3x.getTemperatureC());
	Serial.print(" C/");
	/**
   * getTemperatureF Get the measured temperature (in degrees Fahrenheit).
   * @return Return the float temperature data. 
   */
	Serial.print(sht3x.getTemperatureF());
	Serial.print(" F ");
	Serial.print("Relative humidity(%RH):");
	/**
   * getHumidityRH Get measured humidity(%RH)
   * @return Return the float humidity data
   */
	Serial.print(sht3x.getHumidityRH());
	Serial.println(" %RH");
	//Please adjust the frequency of reading according to the frequency of the chip collection data.
	//The frequency to read data must be greater than the frequency to collect the data, otherwise the returned data will go wrong.
	delay(100);
	if(millis() > 10000 && millis() < 10200) {
		/**
     * stopPeriodicMode() Exit from the cycle read data
     * @return Read the status of the register to determine whether the command was executed successfully, 
     * and return true indicates success.
     */
		sht3x.stopPeriodicMode();
		Serial.println("Exited from the cycle measurement mode, enter the single measurement mode");
	}
	/**
   * readTemperatureAndHumidity Get temperature and humidity data in cycle measurement mode and use structures to receive data
   * @return Return a structure containing celsius temperature (°C), Fahrenheit temperature (°F), relative humidity (%RH), status code.
   * @n A status of 0 indicates that the right return data.
  SHT3x::sRHAndTemp_t data = sht3x.readTemperatureAndHumidity();
  if(data.ERR == 0){
    Serial.print("ambient temperature(°C/F):");
    Serial.print(data.TemperatureC);
    Serial.print("C/");
    Serial.print(data.TemperatureF);
    Serial.print("F");
    Serial.print("relative humidity(%RH):");
    Serial.print(data.Humidity);
    Serial.println("%RH");
  }
  */
}

Test Methods and Results

Serial print the temperature and humidity information in period measurement mode for 10s, then exit from this mode and enter single measurement mode, and print the information.

Sht31-period.png

(3) Temperature & Humidity Alarm

Set the temperature and humidity threshold. The pin INT generates alarm signal when exceeding the threshold.

When using this example, the pin INT of the sensor needs to be connected to the corresponding interrupt pin of main-board, refer to the pin list in the code below:

Note: the pin INT only works properly in period measurement mode.

#include <SHT3x.h>
/*!
 * @brief Construct the function
 * @param pWire IIC bus pointer object and construction device, can both pass or not pass parameters, Wire in default.
 * @param address Chip IIC address, two optional addresses 0x44 and 0x45(0x45 in default).
 * @param RST Chip reset pin, 4 in default.
 * @n IIC address is determined by the pin addr on the chip.
 * @n When the ADR is connected to VDD, the chip IIC address is 0x45.
 * @n When the ADR is connected to GND, the chip IIC address is 0x44.
 */
//SHT3x sht3x(&Wire,/*address=*/0x45,/*RST=*/4);
SHT3x sht3x;
//The non-alarm status of the alert pin is low;
volatile  int alertState = 0;
void alert() {
	alertState = 1 - alertState;
}
void setup() {
	Serial.begin(9600);
	#ifdef ARDUINO_ARCH_MPYTHON 
	/*                    The Correspondence Table of ESP32 Interrupt Pins And Terminal Numbers
   * -----------------------------------------------------------------------------------------------------
   * |            |  DigitalPin  | P0-P20 can be used as an external interrupt                           |
   * |    esp32   |--------------------------------------------------------------------------------------|
   * |            | Interrupt No |  DigitalPinToInterrupt (Pn) can be used to query the interrupt number |
   * |---------------------------------------------------------------------------------------------------|
   */
	attachInterrupt(digitalPinToInterrupt(P16)
	/*Query the interrupt number of the P16 pin*/
	,alert,CHANGE);
	//Open esp32's P16 pin for external interrupt, bilateral edge trigger, ALERT connected to P16
	# else
	/*    The Correspondence Table of AVR Series Arduino Interrupt Pins And Terminal Numbers
   * ---------------------------------------------------------------------------------------
   * |                                        |  DigitalPin  | 2  | 3  |                   |
   * |    Uno, Nano, Mini, other 328-based    |--------------------------------------------|
   * |                                        | Interrupt No | 0  | 1  |                   |
   * |-------------------------------------------------------------------------------------|
   * |                                        |    Pin       | 2  | 3  | 21 | 20 | 19 | 18 |
   * |               Mega2560                 |--------------------------------------------|
   * |                                        | Interrupt No | 0  | 1  | 2  | 3  | 4  | 5  |
   * |-------------------------------------------------------------------------------------|
   * |                                        |    Pin       | 3  | 2  | 0  | 1  | 7  |    |
   * |    Leonardo, other 32u4-based          |--------------------------------------------|
   * |                                        | Interrupt No | 0  | 1  | 2  | 3  | 4  |    |
   * |--------------------------------------------------------------------------------------
   */
	/*                      The Correspondence Table of micro:bit Interrupt Pins And Terminal Numbers
   * ---------------------------------------------------------------------------------------------------------------------------------------------
   * |             micro:bit                       | DigitalPin |P0-P20 can be used as an external interrupt                                     |
   * |  (When using as an external interrupt,      |---------------------------------------------------------------------------------------------|
   * |no need to set it to input mode with pinMode)|Interrupt No|Interrupt number is a pin digital value, such as P0 interrupt number 0, P1 is 1 |
   * |-------------------------------------------------------------------------------------------------------------------------------------------|
   */
	attachInterrupt(
	/*Interrupt No*/
	0,alert,CHANGE);
	//Open the external interrupt 0, connect ALERT to the digital pin of the main control: 
	//UNO(2), Mega2560(2), Leonardo(3), microbit(P0).
	#endif
	    //Initialize the chip to detect if it can communicate properly
	while (sht3x.begin() != 0) {
		Serial.println("The initialization of the chip is failed, please confirm whether the chip connection is correct");
		delay(1000);
	}
	/**
   * readSerialNumber Read the serial number of the chip
   * @return Return 32-digit serial number
   */
	Serial.print("The chip serial number");
	Serial.println(sht3x.readSerialNumber());
	/**
   * softReset Send command resets via iiC, enter the chip's default mode single-measure mode, turn off the heater, 
   * and clear the alert of the ALERT pin.
   * @return Read the status register to determine whether the command was executed successfully, and returning true indicates success.
   */
	if(!sht3x.softReset()) {
		Serial.println("Failed to reset the chip");
	}
	/**
   * @brief All flags (Bit 15, 11, 10, 4) in the status register can be cleared (set to zero).
   * @n ALERT can work properly only when the bit:15 is set to 0, otherwise it will remain high.
   */
	sht3x.clearStatusRegister();
	/**
   * startPeriodicMode Enter cycle measurement mode and set repeatability, read frequency, and only in this mode ALERT can work.
   * @param measureFreq Read the data frequency, data type eMeasureFrequency_t
   * @note  Selectable parameters:
               eMeasureFreq_Hz5,   /**the chip collects data in every 2s
               eMeasureFreq_1Hz,   /**the chip collects data in every 1s 
               eMeasureFreq_2Hz,   /**the chip collects data in every 0.5s 
               eMeasureFreq_4Hz,   /**the chip collects data in every 0.25s 
               eMeasureFreq_10Hz   /**the chip collects data in every 0.1s 
   * @param repeatability Read the repeatability of temperature and humidity data, the default parameter is eRepeatability_High.
   * @note  Optional parameters:
               eRepeatability_High /**In high repeatability mode, the humidity repeatability is 0.10%RH, the temperature repeatability is 0.06°C
               eRepeatability_Medium,/**In medium repeatability mode, the humidity repeatability is 0.15%RH, the temperature repeatability is 0.12°C.
               eRepeatability_Low, /**In low repeatability mode, the humidity repeatability is0.25%RH, the temperature repeatability is 0.24°C
   * @return Read the status of the register to determine whether the command was executed successfully, and return true indicates success.
   */
	if(!sht3x.startPeriodicMode(sht3x.eMeasureFreq_10Hz)) {
		Serial.println("Failed to enter the periodic mode");
	}
	/**
   * setTemperatureLimitC Set the threshold temperature and alarm clear temperature(°C)
   * setTemperatureLimitF Set the threshold temperature and alarm clear temperature(°F)
   * @param highset High temperature alarm point, when the temperature is greater than this value, the ALERT pin generates an alarm signal.
   * @param highClear High temperature alarm clear point, alarming when the temp higher than the highset, otherwise the alarm signal will be cleared.
   * @param lowset Low temperature alarm point, when the temperature is lower than this value, the ALERT pin generates an alarm signal.
   * @param lowclear Low temperature alarm clear point, alarming when the temp lower than the highset, otherwise the alarm signal will be cleared.
   * @note The filled value should be an integer (range: -40 to 125 degrees Celsius), -40 to 257 (Fahrenheit)highset>highClear>lowclear>lowset)
   */
	//sht3x.setTemperatureLimitF(/*highset=*/35,/*highClear=*/34,/*lowSet=*/18,/*lowClear=*/20)
	if(sht3x.setTemperatureLimitC(
	/*highset=*/
	35,
	/*highClear=*/
	34,
	/*lowSet=*/
	18,
	/*lowClear=*/
	20) != 0) {
		Serial.println("Failed to set the temperature limit");
	}
	/**
   * setHumidityLimitRH Set the relative humidity threshold temperature and the alarm clear humidity(%RH)
   * @param highset High humidity alarm point, when the humidity is greater than this value, the ALERT pin generates an alarm signal.
   * @param highClear High humidity alarm clear point, alarming when the humidity higher than the highset, otherwise the alarm signal will be cleared.
   * @param lowset Low humidity alarm point, when the humidity is lower than this value, the ALERT pin generates an alarm signal.
   * @param lowclear Low humidity alarm clear point, alarming when the humidity lower than the highset, otherwise the alarm signal will be cleared.
   * @note The filled value should be an integer (range: 0 - 100 %RH,highset>highClear>lowclear>lowset) 
   */
	if(sht3x.setHumidityLimitRH(
	/*highset=*/
	70,
	/*highClear=*/
	68,
	/*lowSet=*/
	19,
	/*lowClear=*/
	20) != 0) {
		Serial.println("Failed to set the humidity limit");
	}
	//Serial.println(F("string") Save stings to flash to save the dynamic ram when compiling.
	Serial.println(F("----------------------Alarm Detection-------------------------------"));
	Serial.println(F("Alarms raised when temp and humidity are out of the threshold range. Please connect ALERT to the main control board interrupt pin"));
	Serial.println(F("-Different main contorl UNO(2), Mega2560(2), Leonardo(3), microbit(P0), mPython(P16)----"));
	Serial.println(F("----------------------the humidity limit(%RH)-----------------------------------"));
	/**
   * @brief Measure relative humidity threshold temperature and alarm clear humidity
   * @return Return true indicates successful data acquisition
   */
	if(sht3x.measureHumidityLimitRH()) {
		Serial.print("high set:");
		//getHumidityHighSetRH() Get the high humidity alarm point
		Serial.print(sht3x.getHumidityHighSetRH());
		Serial.print("               low clear:");
		//getHumidityHighClearRH() Get the high humidity alarm clear point
		Serial.println(sht3x.getHumidityLowClearRH());
		Serial.print("high clear:");
		//getHumidityLowClearRH() Get the low humidity alarm clear point
		Serial.print(sht3x.getHumidityHighClearRH());
		Serial.print("               low set:");
		//getHumidityLowSetRH() Get the low humidity alarm point
		Serial.println(sht3x.getHumidityLowSetRH());
	} else {
		Serial.println("Failed to get the humidity limit");
	}
	/**
   * measureTemperatureLimitC Measure the threshold temperature and alarm clear temperature(°C)
   * measureTemperatureLimitF Measure the threshold temperature and alarm clear temperature(°F)
   * @return Return true indicates successful data acquisition
   */
	Serial.println("----------------------temperature limit(°C)---------------------------------");
	//Serial.println(F("----------------------temperature limit(°F)---------------------------------"));
	if(sht3x.measureTemperatureLimitC()) {
		Serial.print("high set:");
		//getTemperatureHighSetC() Get high temperature alarm points(°C)
		//getTemperatureHighSetF() Get high temperature alarm points(°F)
		Serial.print(sht3x.getTemperatureHighSetC());
		Serial.print("               low clear:");
		//getTemperatureHighClearC() Get high temperature alarm clear points(°C)
		//getTemperatureHighClearF() Get high temperature alarm clear points(°F))
		Serial.println(sht3x.getTemperatureLowClearC());
		Serial.print("high clear:");
		//getTemperatureLowClearC() Get low temperature alarm clear points(°C)
		//getTemperatureLowClearF() Get low temperature alarm clear points(°F)
		Serial.print(sht3x.getTemperatureHighClearC());
		Serial.print("               low set:");
		//getTemperatureLowSetC() Get low temperature alarm points(°C)
		//getTemperatureLowSetF() Get low temperature alarm points(°F)
		Serial.println(sht3x.getTemperatureLowSetC());
		Serial.println("------------------------------------------------------------------");
	} else {
		Serial.println("Failed to get temperature limit");
	}
	/**
   * readAlertState Read the status of the ALERT pin.
   * @return High returns 1, low returns 0.
   */
	//To initialize the state of ALERT
	if(sht3x.readAlertState() == 1) {
		alertState = 1;
	} else {
		alertState = 0;
	}
}
void loop() {
	Serial.print("environment temperature(°C/F):");
	/**
   * getTemperatureC Get the measured temperature (in degrees Celsius)
   * @return Return temperature data of the type float
   */
	Serial.print(sht3x.getTemperatureC());
	Serial.print(" C/");
	/**
   * getTemperatureF Get the measured temperature (in degrees Celsius)
   * @return Return temperature data of the type float
   */
	Serial.print(sht3x.getTemperatureF());
	Serial.print(" F      ");
	Serial.print("relative humidity(%RH):");
	/**
   * getHumidityRH Get measured humidity (in %RH)
   * @return Return humidity data of the type float
   */
	Serial.print(sht3x.getHumidityRH());
	Serial.println(" %RH");
	//The read data frequency should greater than the frequency to collect data, otherwise the return data will make errors.
	if(alertState == 1) {
		/**
     * @brief Determine if the temperature and humidity are out of the threshold range
     * @return Return the status code, representing as follows
     * @n 01 Indicates that the humidity exceeds the lower threshold range
     * @n 10 Indicates that the temperature exceeds the lower threshold range
     * @n 11 Indicates that both the humidity and the temperature exceed the lower threshold range
     * @n 02 Indicates that the humidity exceeds the upper threshold range
     * @n 20 Indicates that the temperature exceeds the upper threshold range
     * @n 22 Indicates that both the humidity and the temperature exceed the upper threshold range
     * @n 12 Indicates that the temperature exceeds the lower threshold range,
     //and the humidity exceeds the upper threshold range
     * @n 21 Indicates that the temperature exceeds the upper threshold range,
     //and the humidity exceeds the lower threshold range
     * @n 0  Back to normal, but the alarm is not cleared.
     */
		uint8_t state = sht3x.environmentState();
		//Serial.println(F("string") Save stings to flash to save the dynamic ram when compiling.
		if(state == 1)  Serial.println(F("The humidity exceeds the lower threshold range!")); else if(state == 10)  Serial.println(F("The temperature exceeds the lower threshold range!")); else if(state == 11)  Serial.println(F("The humidity and the temperature exceed the lower threshold range!")); else if(state == 2)   Serial.println(F("The humidity exceeds the upper threshold range!")); else if(state == 20)  Serial.println(F("The temperature exceeds the upper threshold range!")); else if(state == 22)  Serial.println(F("The humidity and the temperature exceed the upper threshold range!")); else if(state == 12)  Serial.println(F("The temperature exceeds the lower threshold range,the humidity exceeds the upper threshold range!")); else if(state == 21)  Serial.println(F("The temperature exceeds the upper threshold range, and the humidity exceeds the lower threshold range!")); else Serial.println(F("T&H back to normal, but the alarm is not cleared!"));
	} else {
		Serial.println(F("T&H in normal range, alarm cleared"));
	}
	delay(1000);
}

Test Methods and Results

Sht31-alert.png

Demo for Raspberry Pi

import smbus
import time
i2c = smbus.SMBus(1)
addr=0x44
i2c.write_byte_data(addr,0x23,0x34)
time.sleep(0.5)
while 1:
	i2c.write_byte_data(addr,0xe0,0x0)
	data = i2c.read_i2c_block_data(addr,0x0,6)
	rawT = ((data[0]) << 8) | (data[1])
	rawR = ((data[3]) << 8) | (data[4])
	temp = -45 + rawT * 175 / 65535
	print (str(temp) +"C")
	RH = 100 * rawR / 65535
	print (str(RH) +"%")
	time.sleep(1)
	print ("*************")

Test Methods and Results

1. Save the test code as a folder in the Raspberry Pi system.

2. The I2C communication function is used in the code. Since the Raspberry Pi does not enable the I2C function by default, you need to enable that before running the code.

A. Enter “sudo raspi-config” in the terminal to start the Raspberry Pi configuration interface.

B. Turn on the I2C function of Raspberry Pi according to the steps below.

Long long.jpg

Execute the following commands in the terminal to run the program. The temperature and humidity data of the current environment will be displayed in the terminal.

sudo python3 SHT31.py