Example Code for Arduino-Temperature & Humidity Alarm
This project demonstrates how to configure temperature and humidity thresholds, where the INT pin generates an alarm signal whenever the measured value exceeds the set limit.
Hardware Preparation
- DFRduino UNO R3 (or similar) x 1
- SHT30 Temperature and Humidity Sensor x 1
- Connectors x 1
Software Preparation
- Arduino IDE
- Download and install the SHT3x Library and Example Programs. (About how to install the library?)
Wiring Diagram
- Connect the sensor’s INT pin to the main board’s interrupt pin (refer to the code for pin correspondence).
Sample Code
The INT pin only works in period measurement mode.
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:
/*!
* @file alert.ino
* @brief Temperature and humidity over-threshold alarm.
* @n Experimental phenomenon: The user can customize the temperature and humidity thresholds,
* and the ALERT pin generates an alarm signal once the values exceed the user-defined threshold.
* @n NOTE: The ALERT pin on the sensor should be connected to the interrupt pin on the main panel when using this function.
* @copyright Copyright (c) 2010 DFRobot Co.Ltd (https://www.dfrobot.com)
* @licence The MIT License (MIT)
* @author [fengli]([email protected])
* @version V1.0
* @date 2019-08-26
* @get from https://www.dfrobot.com
* @url https://github.com/DFRobot/DFRobot_SHT3x
*/
#include <DFRobot_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.
*/
//DFRobot_SHT3x sht3x(&Wire,/*address=*/0x45,/*RST=*/4);
DFRobot_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);
}
Result
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