Arduino – Raspberry Pi Web Based Fan Switch

In this project we are going to use an Arduino to get the room temperature, and be able to turn on a regular house fan. The Arduino sends the temperature value to the Raspberry Pi using the Serial Communication, the Pi’s Python script takes the value and saves it to a text file. A PHP script then dynamically builds a web page and includes a link to turn the fan on or off. When clicked this changes the value in a text file, the python script reads the text file, and sends a command to the Arduino.

Prerequisites

Functional Parts in the Project:

Arduino Uno – https://store.arduino.cc/usa/arduino-uno-rev3
560 Piece Jumper Wire Kit – https://amzn.to/2MsCLjL
Breadboard Kit – https://amzn.to/2Xih5ei
Analog Temperature Sensor – https://amzn.to/2Rkkl3k
Raspberry Pi
USB Cable
DLI IoT Relay – https://amzn.to/2zPR3ou
Fan or Other Plugin electric Device

Arduino Sketch

String command;

#define sensorPin A0
#define fan 8

void setup() {
  Serial.begin(9600);
  pinMode(fan, OUTPUT);
}

void loop() {
  int reading = analogRead(sensorPin);
  float voltage = reading * 5.0;
  voltage /= 1024.0;
  float temperatureC = (voltage - 0.5) * 100 ;
  float temperatureF = (temperatureC * 9.0 / 5.0) + 32.0;

  Serial.println(temperatureF);
  
  if (Serial.available()) {
    command = Serial.readStringUntil('\n');
    command.trim();
    if (command.equals("on")) {
      digitalWrite(fan, HIGH);
    }
    else if (command.equals("off")) {
      digitalWrite(fan, LOW);
    }
    else {
      digitalWrite(fan, HIGH);
      delay(500);
      digitalWrite(fan, LOW);
    }

  }
  delay(1000);
}

Linux Setup

sudo apt-get install apache2

sudo apt-get install php

sudo chown pi /var/www/html

sudo chmod 777 /var/www/html/data.txt

sudo chmod 777 /var/www/html/fanStatus.txt

fanApp.py

import serial

if __name__ == '__main__':
    ser = serial.Serial('/dev/ttyACM0',9600, timeout=1)
    ser.flush()
    
    while True:

        if ser.in_waiting > 0:
            line = ser.readline().decode('utf-8').rstrip()
            tempFile = open("/var/www/html/data.txt","w")
            tempFile.write(line)
            tempFile.close()
            
            print("***")

            fanFile = open("/var/www/html/fanStatus.txt","r")
            command = fanFile.read()
            fanFile.close()
            
            print(line)
            if command == 'on':
                ser.write(b"on\n")
                print(command)
            elif command == 'off':
                ser.write(b"off\n")
                print(command)
            else:
                print("error")

fanApp.php

<meta http-equiv="refresh" content="5">

<?php
print "<h1 style='text-align:center;'>Arduino/Raspberry Pi Temp Web Device</h1>";
print "<br>";

$temp = file_get_contents("data.txt");
$fanSwitch;
$fanTrigger = $_GET["fanSwitch"];

if ($fanTrigger == "on" || $fanTrigger == "off"){
file_put_contents("fanStatus.txt", $fanTrigger);
}

$fanStatus = file_get_contents("fanStatus.txt");

if ($temp > 70){
	$color="red";
	}else {
		$color="green";
	}

if ($fanStatus == "on"){
	$fanSwitch = "off";
} else if ($fanStatus == "off"){
	$fanSwitch = "on";
} else {
	$fanSwitch = "problem";
}
	
print "<p style='text-align:center; font-size:200px; margin-top: 10px; margin-bottom: 10px;color:".$color.";'>".$temp."</p>";


print "<p>Fan is ".$fanStatus."</p>";

print "<a href='fanApp.php?fanSwitch=".$fanSwitch."'>Turn Fan ".$fanSwitch."</p></a>";

?>