Published August 7, 2017 © GPL3+

Cooler Status Monitor

Keep your drinks nearby and cool on hot summer days!

IntermediateFull instructions provided5 hours1,103

Things used in this project

Hardware components

Onion Corporation Omega2 Plus

Onion Corporation Onion Arduino Dock 2

Buzzer

Photo resistor

LED (generic)

I used a white one, but anything works.

Temperature Sensor

Breadboard (generic)

Jumper wires (generic)

You need a lot of these

Resistor 330 ohm

You need this to connect the photoelectric sensor (aka photo resistor). A 220 ohm one also will do the job.

Resistor 1k ohm

You need a resistor to connect the LED, I used a 1K

Software apps and online services

Losant Platform

Story

Intro

My family and I enjoy visiting the beach, especially on hot summer days. We always bring out a cooler full of ice and cold drinks, which are extremely refreshing when sitting on the beach for a long time on a hot day. However, we sometimes find the drinks hotter than they should be, and we also sometimes forget to close our cooler, making the ice melt a lot quicker.

(Photo from Wikimedia to make this long section more interesting)

For this contest I decided to build a device that will remind us to close the lid of the cooler, allow us to monitor the temperature from our phones, and also play a loud, obnoxious noise when someone tries to move the cooler.

Part 1

The heart of this device is the Omega 2+, which I used with an Arduino Dock 2 to make the programming and connectivity with sensors easier. Ignoring the messy wires in the picture below, you can see the Omega 2+ (covered by a piece of paper because my information is written on it) on the Arduino Dock 2 connected to a photoelectric sensor, a piezo buzzer, a very accurate temperature sensor, and a tilt sensor. A more clear schematic is also included below. The LED is also included for testing (so my ears are not damaged by the very obnoxious noise from the buzzer); when the buzzer is supposed to be silent, the LED is on.

Sorry for the messy wiring, but this is my project.

Part 2

The temperature data is sent via WiFi to Losant, so you can view the temperature data in a graph as well as in real time from your phone. The graph (of temperature readings when the device is in a hot room) is shown below.

Graph of temperature data sent to Losant from the temperature sensor

In order to set up Losant, I used the tutorial on Onion's free Omega2 Project Book. The project I followed was the Smart Plant project, and I modified the code to fit my needs. My code is linked below. If you follow it, be sure to add in your own Losant device ID, key, and secret code into the losant.json file (not included in my github repository).

Conclusions

In the future, the OLED expansion can be added on top of the Omega2+ to allow you to view temperature data without your phone or an internet connected device, as well as a GPS module connected to the USB port so you can locate the cooler if someone does steal it. I will also be 3D printing a case to install this project in my family cooler.

Code

/*
 * Jerry Zhang's 2017 Omega-thon Project
 * Cooler Status Monitor
 * 
 * Some code samples from Sparkfun's SIK Guide
 */
float MAXTEMP = 90; // Set maximum temperature (in Fahrenheit) before the buzzer goes off
int COOLER_OPEN_LIGHT_LEVEL = 100; // Set light level when cooler is open, between 0 and 255

// Calibrating the light sensor
int lightLevel;
int calibratedlightLevel;
int maxThreshold = 0;
int minThreshold = 1023;


// Analog Pins
const int temperaturePin = 0;
const int photoresistorPin = 1;

// Digital Pins
const int buzzerPin = 9;
const int tiltSensorPin = 7;
const int ledPin = 12; // LED for testing purposes

void setup() {
  pinMode(buzzerPin, OUTPUT);
  pinMode(tiltSensorPin, INPUT);
  pinMode(ledPin, OUTPUT);
}

void loop() {
  // Temp sensor
  float voltage = getVoltage(temperaturePin); // getVoltage function written below
  float degreesF = (voltage - 0.5) * 100.0 * (9.0/5.0) + 32.0;

  bool tilt = digitalRead(tiltSensorPin); // The tilt sensor acts like a button: if it's tilted the value is true, otherwise it's false

  lightLevel = analogRead(photoresistorPin); // Read voltage on sensorPin
  calibratedlightLevel = map(lightLevel, 0, 1023, 0, 255); // scale to 0-255 range. Map is a built in arduino function

  if (degreesF > MAXTEMP || tilt || lightLevel > COOLER_OPEN_LIGHT_LEVEL) { // if it's too hot or the cooler is being tilted (it's being rolled away), then the buzzer goes off
    digitalWrite(ledPin, LOW);
    tone(buzzerPin, 523, 1000); // the tone function takes the pin, the frequency of the note, and how long (in ms) the note should go for.
  } else {
    digitalWrite(ledPin, HIGH);
  }

  

  delay(1000);
}

float getVoltage(int pin) {
  return (analogRead(pin) * 0.004882814);
  
  // This equation converts the 0 to 1023 value that analogRead()
  // returns, into a 0.0 to 5.0 value that is the true voltage
  // being read at that pin.
}

Credits

Jerry Zhang

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