Basic Thermometer

Summary

      A basic thermometer build with Arduino using the Arduino Micro board to read the temperature and humidity.

Description

      The device will read the temperature and humidity from the DHT 11 sensor. Afterware, it will display the data in the LCD 1602 and at the same time it will have an RGB Led that will change it color depending on the temperature. For the RGB Led I build a class to make it easy to use and export it as a library.

Tools & Technologies

• Hardware & Software - Arduino
• CAD - Autodesk Fusion
• Electronic Circuit Design - Circuit Maker
• Language - C++

Funtional Architecture

Electronic Circuit Schematic

3D Model

Thermometer Images

Code

Importing Libraries and Defining variables

#include <LiquidCrystal.h>
#include <TemperatureLed.h>
#include <DHT.h>

#define LCD_CONTRAST_PIN 6
#define LCD_BACKLIGHT_PIN 10

#define DHT_TYPE DHT11
#define DHT_PIN 8

#define RED_PIN 18
#define GREEN_PIN 19
#define BLUE_PIN 20

Creating the Objects

LiquidCrystal lcd(13, 12, 5, 4, 3, 2);  
TemperatureLed led(RED_PIN, GREEN_PIN, BLUE_PIN);
DHT dht(DHT_PIN, DHT_TYPE);

Setup function

void setup() {  

    Serial.begin(9600);

    // Temperature Sensor Begin
    dht.begin();

    pinMode(9, OUTPUT);

    analogWrite(9, 100);

    analogWrite(LCD_BACKLIGHT_PIN, 255);

    analogWrite(LCD_CONTRAST_PIN, 150);

    // Display Begin
    lcd.begin(16, 2);

    // Led Begin
    led.begin();
}

Loop function

void loop() {  

    // Read sensor data
    float humidity = dht.readHumidity();

    float fahrenheit = dht.readTemperature(true);

    // This Condition Section verify the temperature and then change the Led color
    if(fahrenheit <= 68.5) {

        led.changeLedColor(led.blueColor);

    } else if((fahrenheit >= 68.6) && (fahrenheit <= 72.5)) {
        
        led.setCustomLedColor(0, 255, 255);

    } else if((fahrenheit >= 72.6) && (fahrenheit <= 76.5)) {
        
        led.changeLedColor(led.greenColor);

    } else if((fahrenheit >= 76.6) && (fahrenheit <= 80.5)) {
        
        led.setCustomLedColor(255, 255, 0);

    } else if(fahrenheit >= 80.6) {
        
        led.changeLedColor(led.redColor);
    }

    // LCD print Section
    lcd.setCursor(0, 0);

    lcd.print("Temp: ");
    lcd.print(fahrenheit, 0);
    lcd.print((char)223);
    lcd.print("F");


    lcd.setCursor(0, 1);

    lcd.print("Humidity: ");
    lcd.print(humidity, 0);
    lcd.print("%");

    delay(10000);
}

The class for the RGB Led is build

class RGBLed
{
    public:
        RGBLed(int redPin, int greenPin, int bluePin);
        int redColor[3] = {255,0,0};
        int greenColor[3] = {0,255,0};
        int blueColor[3] = {0,0,255};

        void begin();
        void changeLedColor(int color[3]);
        void setCustomLedColor(int redColor, int greenColor, int blueColor);

    private:
        int _redPin;
        int _greenPin;
        int _bluePin;
};

Here in the constructor the pins are assigned

RGBLed::RGBLed(int redPin, int greenPin, int bluePin) {
    _redPin = redPin;
    _greenPin = greenPin;
    _bluePin = bluePin;
}

This function set the pins to Output

void RGBLed::begin() {
    pinMode(_redPin, OUTPUT);
    pinMode(_greenPin, OUTPUT);
    pinMode(_bluePin, OUTPUT);
}

This function change the Led Color with predefined colors

void RGBLed::changeLedColor(int color[3]) {
    analogWrite(_redPin, color[0]);
    analogWrite(_greenPin, color[1]);
    analogWrite(_bluePin, color[2]);
}

This function change the color to the color we want

void RGBLed::setCustomLedColor(int redColor, int greenColor, int blueColor) {
    analogWrite(_redPin, redColor);
    analogWrite(_greenPin, greenColor);
    analogWrite(_bluePin, blueColor);
}