Youtube Video

Published April 17, 2018 © GPL3+

IOT Particle Temperature Sensor

Are you ever sitting in your room gaming with your friends and your room gets really warm? Our solution, an IOT temperature sensor!

IntermediateShowcase (no instructions)12 hours1,230

Things used in this project

Hardware components

Particle Photon

Resistor 10k ohm

DHT11 Temperature & Humidity Sensor (4 pins)

FAN

Jumper wires (generic)

Software apps and online services

Particle IDE

Story

For this project we had to come up with a problem that could be solved using particles and their WiFi capabilities. Most college kids enjoy playing video games. Its a break from school, a way to interact with friends, and just a fun way to relax on the weekend. But sitting in your tiny dorm room after a few games of PUBG, your room starts to get warm from your system overheating. It's especially worse when all your friends are gathered together. To fix this issue we wired our particles a DHT11 sensor, to monitor the temperature and fan to cool down the temperature.

To begin this project we started by ordering a DHT11 sensor, which monitors temperature and humidity in a room. To code our particle to be able to read this data, we downloaded the code from the particle library. Next we had to wire the DHT11 sensor to constant voltage and connecting the data port to one of the digital ports on the particle. After this we had to code the particle to publish events based on the temperature in the room; these events are published through the cloud onto the particle console page. From there we began connecting the second particle. We ordered a fan online, which was a lot smaller than expected. To account for this we set the HOTROOM temperature to above 80, this way you can see the fan shut off when it cools down the temperature (in our video). We had to code the second particle to subscribe to the events from the first particle and send HIGH or LOW digitalwrite to the ports; this will turn the fan on or off. This particle then sends a publish to the first particle telling it whether the fan is on or off. If the fan is on the d7 led will light up.

Youtube Video

Temperature Graph

https://thingspeak.com/channels/495571/private_show

The initial error in the graph comes from the start up of the particle.

Code

// This #include statement was automatically added by the Particle IDE.
#include "Adafruit_DHT.h"

// DHT parameters
#define DHTPIN 2
#define DHTTYPE DHT11



// Variables
int temperature;
int humidity;
int LED=D7;

// DHT sensor
DHT dht(DHTPIN, DHTTYPE);


void setup() {
Particle.subscribe("jl_boardled", LEDON, "39002b000651353530373132");
Particle.subscribe("jl_boardledoff", LEDOFF, "39002b000651353530373132");
pinMode(LED,OUTPUT);
digitalWrite(LED,LOW);
    // Start DHT sensor
    dht.begin();
}


void LEDON(const char*event, const char *data){
digitalWrite(LED,HIGH);
}
void LEDOFF(const char*event, const char *data){
  digitalWrite(LED,LOW);
}

void loop() {


    // Humidity measurement
    temperature = dht.getTempFarenheit();

    // Humidity measurement
    humidity = dht.getHumidity();



    Particle.publish ("temperature", String(temperature) + " °F");
     delay(500);
     Particle.publish ("humidity", String(humidity) + "%");
     delay(500);

     String temp = String(temperature);
     Particle.publish("temp", temp, PRIVATE);
 delay(30000);


 if( temperature > 80 ) {
 // if condition is true then print the following
  Particle.publish("jl_HOTROOM", "True");
} else {
 // if condition is false then print the following
  Particle.publish("jl_COLDROOM", "True");
}
}

int fan = D2;
int fan2 = D3;
int fan3 = D4;
int fan4 =D5;

 
void setup() {
    
     Particle.subscribe("jl_HOTROOM", FANON, "23003a001247343438323536");
     Particle.subscribe("jl_COLDROOM", FANOFF, "23003a001247343438323536");
    
    pinMode(fan, OUTPUT);
    digitalWrite(fan, LOW);
    pinMode(fan2, OUTPUT);
    digitalWrite(fan2, LOW);
    pinMode(fan3, OUTPUT);
    digitalWrite(fan3, LOW);
    pinMode(fan4,OUTPUT);
    digitalWrite(fan4,LOW);
}
 

 void FANON(const char *event, const char *data){
 
    digitalWrite(fan, HIGH);
    digitalWrite(fan2, HIGH);
    digitalWrite(fan3, HIGH);
    digitalWrite(fan4,HIGH);
    Particle.publish("jl_fanon", "1");
    Particle.publish("jl_boardled","true");
}
 

 void FANOFF(const char *event, const char *data){
 
    digitalWrite(fan, LOW);
    digitalWrite(fan2, LOW);
    digitalWrite(fan3,LOW);
    digitalWrite(fan4,LOW);
    Particle.publish("jl_fanon", "0");
    Particle.publish("jl_boardledoff","true");
 }

/* DHT library
 *
 * MIT license
 * written by Adafruit Industries
 * modified for Spark Core by RussGrue
 * */

#include "Adafruit_DHT.h"

DHT::DHT(uint8_t pin, uint8_t type, uint8_t count) {
	_pin = pin;
	_type = type;
	_count = count;
	firstreading = true;
}

void DHT::begin(void) {
// set up the pins!
	pinMode(_pin, INPUT);
	digitalWrite(_pin, HIGH);
	_lastreadtime = 0;
}

float DHT::readTemperature() {
	float f;

	if (read()) {
		switch (_type) {
			case DHT11:
				f = data[2];
				return f;
			case DHT22:
			case DHT21:
				f = data[2] & 0x7F;
				f *= 256;
				f += data[3];
				f /= 10;
				if (data[2] & 0x80)
					f *= -1;
				return f;
		}
	}
	return NAN;
}

float DHT::getHumidity() {
	return readHumidity();
}

float DHT::getTempCelcius() {
	return readTemperature();
}

float DHT::getTempFarenheit() {
	return convertCtoF(readTemperature());
}

float DHT::getTempKelvin() {
	return convertCtoK(readTemperature());
}

float DHT::getHeatIndex() {
	return convertFtoC(computeHeatIndex(convertCtoF(readTemperature()), readHumidity()));
}

float DHT::getDewPoint() {
	return computeDewPoint(readTemperature(), readHumidity());
}

float DHT::convertFtoC(float f) {
	return (f - 32) * 5 / 9;
}

float DHT::convertCtoF(float c) {
	return c * 9 / 5 + 32;
}

float DHT::convertCtoK(float c) {
	return c + 273.15;
}

float DHT::readHumidity(void) {
	float f;

	if (read()) {
		switch (_type) {
			case DHT11:
				f = data[0];
				return f;
			case DHT22:
			case DHT21:
				f = data[0];
				f *= 256;
				f += data[1];
				f /= 10;
				return f;
		}
	}
	return NAN;
}

float DHT::computeHeatIndex(float tempFahrenheit, float percentHumidity) {
// Adapted from equation at: https://github.com/adafruit/DHT-sensor-library/issues/9 and
// Wikipedia: http://en.wikipedia.org/wiki/Heat_index
	return -42.379 +
		 2.04901523 * tempFahrenheit +
		10.14333127 * percentHumidity +
		-0.22475541 * tempFahrenheit * percentHumidity +
		-0.00683783 * pow(tempFahrenheit, 2) +
		-0.05481717 * pow(percentHumidity, 2) +
		 0.00122874 * pow(tempFahrenheit, 2) * percentHumidity +
		 0.00085282 * tempFahrenheit * pow(percentHumidity, 2) +
		-0.00000199 * pow(tempFahrenheit, 2) * pow(percentHumidity, 2);
}

float DHT::computeDewPoint(float tempCelcius, float percentHumidity) {
	double a = 17.271;
	double b = 237.7;
	double tC = (a * (float) tempCelcius) / (b + (float) tempCelcius) + log( (float) percentHumidity / 100);
	double Td = (b * tC) / (a - tC);
	return Td;
}


boolean DHT::read(void) {
	uint8_t laststate = HIGH;
	uint8_t counter = 0;
	uint8_t j = 0, i;
	unsigned long currenttime;

// Check if sensor was read less than two seconds ago and return early
// to use last reading.
	currenttime = millis();
	if (currenttime < _lastreadtime) {
// ie there was a rollover
		_lastreadtime = 0;
	}
	if (!firstreading && ((currenttime - _lastreadtime) < 2000)) {
		return true; // return last correct measurement
//		delay(2000 - (currenttime - _lastreadtime));
	}
	firstreading = false;
/*
	Serial.print("Currtime: "); Serial.print(currenttime);
	Serial.print(" Lasttime: "); Serial.print(_lastreadtime);
*/
	_lastreadtime = millis();

	data[0] = data[1] = data[2] = data[3] = data[4] = 0;

// pull the pin high and wait 250 milliseconds
	digitalWrite(_pin, HIGH);
	delay(250);

// now pull it low for ~20 milliseconds
	pinMode(_pin, OUTPUT);
	digitalWrite(_pin, LOW);
	delay(20);
	noInterrupts();
	digitalWrite(_pin, HIGH);
	delayMicroseconds(40);
	pinMode(_pin, INPUT);

// read in timings
	for ( i=0; i< MAXTIMINGS; i++) {
		counter = 0;
		while (digitalRead(_pin) == laststate) {
			counter++;
			delayMicroseconds(1);
			if (counter == 255) {
				break;
			}
		}
		laststate = digitalRead(_pin);

		if (counter == 255) break;

// ignore first 3 transitions
		if ((i >= 4) && (i%2 == 0)) {
// shove each bit into the storage bytes
			data[j/8] <<= 1;
			if (counter > _count)
				data[j/8] |= 1;
			j++;
		}

	}

	interrupts();

/*
	Serial.println(j, DEC);
	Serial.print(data[0], HEX); Serial.print(", ");
	Serial.print(data[1], HEX); Serial.print(", ");
	Serial.print(data[2], HEX); Serial.print(", ");
	Serial.print(data[3], HEX); Serial.print(", ");
	Serial.print(data[4], HEX); Serial.print(" =? ");
	Serial.println(data[0] + data[1] + data[2] + data[3], HEX);
*/

// check we read 40 bits and that the checksum matches
	if ((j >= 40) &&
	   (data[4] == ((data[0] + data[1] + data[2] + data[3]) & 0xFF)) ) {
		return true;
	}

	return false;

}

/* DHT library
 *
 * MIT license
 * written by Adafruit Industries
 * modified for Spark Core by RussGrue
 * */

#ifndef DHT_H
#define DHT_H

#include "application.h"
#include "math.h"

// how many timing transitions we need to keep track of. 2 * number bits + extra
#define MAXTIMINGS 85

#define DHT11 11
#define DHT22 22
#define DHT21 21
#define AM2301 21

class DHT {
	private:
		uint8_t data[6];
		uint8_t _pin, _type, _count;
		unsigned long _lastreadtime;
		boolean firstreading;
		float readTemperature();
		float convertFtoC(float);
		float convertCtoF(float);
		float convertCtoK(float);
		float computeHeatIndex(float tempFahrenheit, float percentHumidity);
		float computeDewPoint(float tempCelcius, float percentHumidity);
		float readHumidity(void);
		boolean read(void);

	public:
		DHT(uint8_t pin, uint8_t type, uint8_t count=6);
		void begin(void);
		float getHumidity();
		float getTempCelcius();
		float getTempFarenheit();
		float getTempKelvin();
		float getHeatIndex();
                float getDewPoint();

};
#endif

Credits

Jennifer Mericle

1 project • 0 followers

Luke Honbarger

1 project • 0 followers

IOT Particle Temperature Sensor

Things used in this project

Hardware components

Software apps and online services

Story

Youtube Video

Schematics

SetUp

Circuit Diagram

Temperature Readings

Circuit

Code

Temperature Sensor

Fan

Adafruit_DHT.cpp

Adafruit_DHT.h

Credits

Jennifer Mericle

Luke Honbarger

Comments

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IOT Particle Temperature Sensor

IOT Particle Temperature Sensor

Things used in this project

Hardware components

Software apps and online services

Story

Youtube Video

Schematics

SetUp

Circuit Diagram

Temperature Readings

Circuit

Code

Temperature Sensor

Fan

Adafruit_DHT.cpp

Adafruit_DHT.h

Credits

Jennifer Mericle

Luke Honbarger

Comments

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