Created November 9, 2020

Lane Tech HS - Too Hot Flag

A little doohickey that gives a visual cue that your room is too hot while recording that time and temperature in a Google Sheet.

BeginnerShowcase (no instructions)5 hours49

Things used in this project

Hardware components

Particle Argon

DHT11 Temperature & Humidity Sensor (4 pins)

SG90 Micro-servo motor

Jumper wires (generic)

Breadboard (generic)

Software apps and online services

Particle Build Web IDE

Google Sheets

Story

This project was part of the Lane Tech HS Physical Computing Lab course. It was created as part of the Sensors and Me IoT project.

Summary

This project's objective is to visually alert the user when their room becomes too hot while recording the time and temperature on a Google Sheet. I decided to embark on this project as the room that has my computer tends to become much warmer than the rest of the house. This is due to the fact that it is above the central heating, but the most isolated from the thermostat. Combine this with the fact that the door tends to stay closed while I'm on the computer and the room becomes very warm, very quickly.

Steps

I started by identifying how I wanted to give a visual cue to the user. After considering multiple methods, I decided on a servo-attached flag that would pop up behind the user's monitor when the room became too hot.

Servo-attached Flag

After deciding the method of notification, I began to prototype my circuit. I attached a DHT11 sensor to a Particle Argon and tested the sensor using the Particle CLI. Using the Adafruit_DHT library was simple for this test, as I only had to use the example in the library. The sensor is quite cheap and as such has a tendency to fail to read.

Test Output

Once I knew that I had a functioning sensor, I then attached a servo to the circuit. I also made the flag by printing out a fire icon and taping it to a piece of cardboard. I then used some tape to affix the flag to the servo so that it would be hidden behind the monitor at 0 degrees. Due to the nature of the servo arm, the flag is initially tilted, but the only thing that matters is that it is straight when the servo is at 180 degrees.

1 / 3 • Circuit without Flag

After some more testing to make sure everything worked, I began to attach everything to my monitors. I decided to use some tape to mount the servo onto the back of my monitor and also extended the cables connecting it, as they were too short to fit in a desirable location.

1 / 2 • Full Implementation of Circuit

I then setup a webhook and Google Sheet to record whenever the flag was triggered, so that I could keep track of it.

Conclusion

The only thing left to do was to now fully test the implemented project. The only drawback was that the entire weekend I was doing this on had very nice weather, which meant the heating was not on and therefore, I had to improvise the difference in temperature with a hair dryer.

Demonstration

Code

#include "Adafruit_DHT.h"

// Written by ladyada, public domain. Modified by Marcin

#define DHTPIN D6

#define DHTTYPE DHT11

DHT dht(DHTPIN, DHTTYPE);
int servoPin = A3;
Servo myServo;
int servoPos = 0;
  
void setup() 
{
  Serial.begin(9600);
  Serial.println("DHT11 test!");
  // attaches the servo on the A3 pin to the servo object
	myServo.attach(A3);
	dht.begin();
}

void loop() 
{
// Wait a few seconds between measurements.
	delay(10000);

	float h = dht.getHumidity();
	float t = dht.getTempCelcius();
	float f = dht.getTempFarenheit();
	float k = dht.getTempKelvin();
// Check if any reads failed and exit early (to try again).
	if (isnan(h) || isnan(t) || isnan(f)) 
	{
		Serial.println("Failed to read from DHT sensor!");
		return;
	}

	Serial.print("\nHumid: "); 
	Serial.print(h);
	Serial.print("% - ");
	Serial.print("Temp: "); 
	Serial.print(t);
	Serial.print("*C ");
	Serial.print(f);
	Serial.print("*F ");
	Serial.print(k);
	Serial.println("*K ");
    
	if (t > 27.0)
	{
	  Serial.println("Room is too hot");
	  Particle.publish("RoomHot", String(t));
	  myServo.write(180);
        
	} else 
	{
	  myServo.write(0);
	}
}

// Enter sheet name where data is to be written below
var SHEET_NAME = "Room DHT Collection";

var SCRIPT_PROP = PropertiesService.getScriptProperties(); // new property service

// If you don't want to expose either GET or POST methods you can comment out the appropriate function
function doGet(e){
  return handleResponse(e);
}

function doPost(e){
  return handleResponse(e);
}

function handleResponse(e) { 
  var lock = LockService.getPublicLock();
  lock.waitLock(30000);  // wait 30 seconds before conceding defeat.

  try {
    // next set where we write the data - you could write to multiple/alternate destinations
    var doc = SpreadsheetApp.openById(SCRIPT_PROP.getProperty("key"));
    var sheet = doc.getSheetByName(SHEET_NAME);

    // we'll assume header is in row 1 but you can override with header_row in GET/POST data
    var headRow = e.parameter.header_row || 1;
    var headers = sheet.getRange(1, 2, 1, sheet.getLastColumn()).getValues()[0];
    var nextRow = sheet.getLastRow()+1; // get next row
    var row = [];

    // loop through the header columns
    for (i in headers){
      if (headers[i] == "Timestamp"){ // special case if you include a 'Timestamp' column
        row.push(new Date());
      } else { // else use header name to get data
        row.push(e.parameter[headers[i]]);
      }
    }
    // more efficient to set values as [][] array than individually
    sheet.getRange(nextRow, 1, 1, row.length).setValues([row]);
    // return json success results
    return ContentService
    .createTextOutput(JSON.stringify({"result":"success", "row": nextRow}))
          .setMimeType(ContentService.MimeType.JSON);
  } catch(e){
    // if error return this
    return ContentService
          .createTextOutput(JSON.stringify({"result":"error", "error": e}))
          .setMimeType(ContentService.MimeType.JSON);
  } finally { //release lock
    lock.releaseLock();
  }
}
function setup() {
    var doc = SpreadsheetApp.getActiveSpreadsheet();
    SCRIPT_PROP.setProperty("key", doc.getId());
}

Lane Tech HS - Too Hot Flag

Things used in this project

Hardware components

Software apps and online services

Story

Summary

Steps

Conclusion

Schematics

Sensors and Me Schematic

Code

Sensors and Me

Pushing Data Script for Google Sheets

Credits

Marcin Gruda

Comments

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Lane Tech HS - Too Hot Flag

Lane Tech HS - Too Hot Flag

Things used in this project

Hardware components

Software apps and online services

Story

Summary

Steps

Conclusion

Schematics

Sensors and Me Schematic

Code

Sensors and Me

Pushing Data Script for Google Sheets

Credits

Marcin Gruda

Comments