Have you ever walked in the kitchen after a long days work or after a long night and noticed that your fridge was not properly closed and hasn't been properly cooling all you food? Well we decided to solve this terrible problem by creating a fridge monitoring system so you never have to get rid of spoiled food or drink warm drinks because the door was left open again. Using knowledge and IOT skills we gained throughout the class and project we have created a argon to argon system that communicates readings and monitors vital elements of the fridge to keep you from ever having a problem again. This project was made with accessibility and ease of construction in mind so anybody can replicate what we created and reap the benefits of this great creation.
The Refrigerator Monitoring System
Throughout the IOT project there were multiple prototypes using multiple sensors and breadboard configurations. The final configurations were chosen because they were simple to make and easy to code. An initial design for the temperature sensor implemented a bmp-180 but this sensor proved to be hard to code and wire correctly, plus each sensor needed to be soldered together for proper use, so we replaced it with a much simpler tmp36 thermistor. The temperature breadboard uses a simple wiring schematic with an analog output to aid in functionality.
Final Temperature sensor breadboard
The photocell board setup also went through multiple iterations like the temperature sensor board to simplify and speed up the creation of the board. The final design just consists of the photocell one 220ohm resistor and jumper wires to connect and extend the wires of the photocell. This simple breakdown can be seen below before the photocycle is extended by jumper cables into the fridge.
Photocell Breadboard Off the Fridge
The two different argons publish and subscribe to events to talk to each other and communicate what they need to execute. The photocell sees if the the fridge light is on or not and publishes a event saying either the fridge light is on or the fridge light is off. Once it publishes the first event the temperature argon then subscribes and can either not do anything if the light is published off or start taking temperature readings if the light is published as on. Once the temperature readings are started to be taken they are uploaded to a external graphing system then when the data cycle stops the temperature argon publishes an event saying its done that the photocell argon can subscribe to and then it checks for the light being on or not and starts the cycle over again. This can be better understood in the flow chart below.
Simple Flow Chart
After the cycle is complete part of the output is the temperature argon sending data to a google sheet that records the different temperature readings that can be graphed inside the sheet. This data can be monitored to see what temperature the fridge is sitting at if the photocell publishes the fridge light is on. A sample run was completed and can be seen in the google sheet picture below. A picture of the photocell argon publishing events for the open and closed door is also below.
This is the code used to operate the light senor circuit.
intled2=D7;intphotoresistor=A0;intanalogValue;voidsetup(){pinMode(led2,OUTPUT);pinMode(photoresistor,INPUT);Particle.variable("photoresistor",analogValue);Particle.subscribe("Temp",value,"e00fce68ed5a561dfd850454");}voidloop(){delay(10000);analogValue=analogRead(photoresistor);if(analogValue>50){digitalWrite(led2,HIGH);Particle.publish("Open","The fridge is open",PRIVATE);delay(1000);}else{digitalWrite(led2,LOW);Particle.publish("Closed","The fridge is closed",PRIVATE);delay(1000);}}
Temperature Sensor Code
C/C++
This is the code used to operate our temp sensor circuit.
#define sensorPin A0voidsetup(){Particle.subscribe("Open",value,"e00fce68ed5a561dfd850454");Particle.subscribe("Closed",close,"e00fce68ed5a561dfd850454");// Begin serial communication at a baud rate of 9600:Serial.begin(9600);}voidloop(){// Get a reading from the temperature sensor:intreading=analogRead(sensorPin);// Convert the reading into voltage:floatvoltage=reading*(590/1024.0);// Convert the voltage into the temperature in Celsius:floattemperature=(voltage-500)/10;Particle.publish("temp",temp,PRIVATE);// Print the temperature in the Serial Monitor:Serial.print(temperature);Serial.print(" \xC2\xB0");// shows degree symbolSerial.println("C");delay(1000);// wait a second between readings}
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