Published April 21, 2023

MEGR 3171 IoT 2 Refrigerator Check

Learn how to monitor your refrigerator temperature. This allows users to protect the food against the heat.

BeginnerFull instructions provided12 hours3

Things used in this project

Hardware components

Particle Argon

Ultrasonic Sensor - HC-SR04 (Generic)

Resistor 100 ohm

Jumper wires (generic)

Breadboard (generic)

DHT11 Temperature & Humidity Sensor (3 pins)

Resistor 330 ohm

LED (generic)

Resistor 220 ohm

Software apps and online services

Particle Build Web IDE

Adafruit IO

Story

This project aims to check the temperature inside your refrigerator without opening it. Knowing the temperature inside of your refrigerator allows you to determine whether your food is staying at a safe temperature and know when your favorite beverage is cold. Each time you open the door to the refrigerator, heat enters the

This project was made by two people; each had a Particle Argon. The data was published in the particle console and, by bidirectional communication, was sent to each other device. The Figure shows the measurement of temperature and "HOLA" sent to the other device to establish the communication.

Ultrasonic Distance Measurements as seen in Particle.io

Webhooks Integration

This tool allowed us to integrate all the data from the sensors used in the Adafruit Io website. The first step to making this integration was to include the Adrafuit IO library in the Particle Web IDE. Next, we had to configure the parameters that Adafruit IO needs to recognize our data measured from the sensors.

Webhooks Config

After the configuration was done, we built the Adafruit IO page and fed the graphs from the data collected. For the Adrafuit page, we needed to create a feed app and a URL that would be necessary to paste into the Webhook configuration to send the data acquired by the sensors.

Data

The data was collected and plotted live. Also, it is possible to set notifications and send those to our phones. When the temperature exceeds 15 degrees C, we will get a notification to solve the problem inside the refrigerator. The distance represents the measurements over time. This measurement is taken in inches, and the user must be farther than 6 inches from the sensor to get a valid notification to be sent to the temperature Argon.

https://io.adafruit.com/Rig0/dashboards/iot

Ultrasonic Sensor To DHT11 Temp Sensor Flowchart

Code

Ultrasonic Distance Sensor

C/C++

Activating this code calculates distance based on the sound waves emitted by the ultrasonic sensor. If the sensor reads out of range or within 6 inches, it returns a value of 0. This value indicates that an individual is not within range of the refrigerator. If the distance is recorded in the correct range, Verify is published. This notifies the Argon with the temperature sensor to report its temperature to this Argon. When doing this, it activates the LED connected to pin D7. This notifies the user that the temperature reading is requested so that one can know the temperature inside of the refrigerator. The distance reading is also sent to io.adafruit and graphed over time.

// This #include statement was automatically added by the Particle IDE.
#include <HC_SR04.h>

// This #include statement was automatically added by the Particle IDE.
#include <Adafruit_IO_Particle.h>



double cm = 0.0;
double inches = 0.0;

int trigPin = D4;
int echoPin = D5;
int receivedinteger = 0;
int led = D7;
int readings = 0;
/*
Connect an HC-SR04 Range finder as follows:
Spark   HC-SR04
GND     GND
5V      VCC
D4      Trig
D5      Voltage divider output - see below

Echo --|
       >
       < 470 ohm resistor
       >
       ------ D5 on Spark
       >
       < 470 ohm resistor
       >
GND ---|

Test it using curl like this:
curl https://api.spark.io/v1/devices/<deviceid>/cm?access_token=<accesstoken>

The default usable rangefinder is 10cm to 250cm. Outside of that range -1 is returned as the distance.

You can change this range by supplying two extra parameters to the constructor of minCM and maxCM, like this:

HC_SR04 rangefinder = HC_SR04(trigPin, echoPin, 5.0, 300.0);

*/

HC_SR04 rangefinder = HC_SR04(trigPin, echoPin);
//receivedfloat = String(data).toFloat();



void setup() 
{
    //Particle.publish("")
    Spark.variable("cm", &cm, DOUBLE);
    Spark.variable("inches", &inches, DOUBLE);
    //Particle.subscribe("Craigs_Distance", Craigs_Distance_Handler);
    pinMode(led, OUTPUT);
    digitalWrite(led, LOW);
    Particle.subscribe("readings", temp);
}

void loop() 
{



    cm = rangefinder.getDistanceCM();
    inches = rangefinder.getDistanceInch();
    delay(100);
    
    
    
    //Particle.publish("reading", String::format("%4.2f", inches));
    
    if (inches >= 6 && inches != -1){
        Particle.publish("Verify", String::format("%4.2f", inches));
        }
        else{
            Particle.publish("Craigs_Distance","0", PUBLIC);
        }
        
        //Particle.publish("Craigs_Distance", String(inches), PUBLIC);
    
    delay(1000);
}

void temp(const char *event, const char *data){
    readings = atoi(data);
    if (readings>=0){
    digitalWrite(led, HIGH);
    delay(500);
    digitalWrite(led, LOW);
    delay(500);
    }
    else{
        }
}
        //Particle.publish("Subscribed_Data", receivedfloat);
    
   // receivedinteger = String(data).toInt();
    //Particle.publish("YES", "%4d", receivedinteger);

DHT-11 Temperature Sensor

C/C++

This code activates an Adafruit DHT-11, a thermometer, and a humidity sensor. The part for the humidity sensor was deleted. This sensor would be located inside the refrigerator and measures the inside temperature of this. The measurements would be sent to the Particle console and to Particle #1. Each time Particle #2 sends data to Particle #1, the LED blinks every 4 seconds. The pin used for it is D7, the same as when Particle #2 receives data from Particle#1. It is connected to Adafruit IO through Webhooks to send the data and get some graphs with the values measured.

#include <ThingSpeak.h>

#include <Adafruit_IO_Particle.h>

#include "Adafruit_DHT_Particle.h"

#define DHTPIN D2   

#define DHTTYPE DHT11		


DHT dht(DHTPIN, DHTTYPE);
int loopCount;
int i = 0;
int led = D7;
void setup() {
    Particle.subscribe("Verify", Craigs_Distance_Handler);
	Serial.begin(9600); 
	Serial.println("DHTxx test!");
	Particle.publish("state", "DHTxx test start");

	dht.begin();
	loopCount = 0;
	delay(2000);
	
	
    pinMode(led, OUTPUT);
    digitalWrite(led, LOW);
    
}
void loop() {
    digitalWrite(led, HIGH);
    Particle.publish("Temp", "HOLA", PUBLIC);
    delay(300);
    digitalWrite(led, LOW);
    delay(4000);

	float h = dht.getHumidity();
	float t = dht.getTempCelcius();
	float f = dht.getTempFarenheit();
  
	if (isnan(h) || isnan(t) || isnan(f)) {
		Serial.println("Failed to read from DHT sensor!");
		return;
	}


	float hi = dht.getHeatIndex();
	float dp = dht.getDewPoint();
	float k = dht.getTempKelvin();


	Serial.print("Temp: "); 
	Serial.print(t);
	Serial.print("*C ");
	
	Serial.println(Time.timeStr());
	//String timeStamp = Time.timeStr();
	Particle.publish("readings", String::format("%4.2f", t));
	delay(20000);
	

	
   
}

SerialLogHandler logHandler; 
void Craigs_Distance_Handler(const char *event, const char *data) {
    int distance = atoi(data);
    if (distance == 0) {
        digitalWrite(led, HIGH);
    } else {
        digitalWrite(led, LOW);
    }
}

Credits

Craig Blackwell

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Rigo Marulanda

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MEGR 3171 IoT 2 Refrigerator Check

Things used in this project

Hardware components

Software apps and online services

Story

Schematics

Ultrasonic Distance Sensor Wiring Diagram

Ultrasonic Sensor with Argon and LED

DHT-11 Temperature Sensor

Code

Ultrasonic Distance Sensor

DHT-11 Temperature Sensor

Credits

Craig Blackwell

Rigo Marulanda

Comments

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MEGR 3171 IoT 2 Refrigerator Check

MEGR 3171 IoT 2 Refrigerator Check

Things used in this project

Hardware components

Software apps and online services

Story

Schematics

Ultrasonic Distance Sensor Wiring Diagram

Ultrasonic Sensor with Argon and LED

DHT-11 Temperature Sensor

Code

Ultrasonic Distance Sensor

DHT-11 Temperature Sensor

Credits

Craig Blackwell

Rigo Marulanda

Comments

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