WiFi Bathroom Humidity Sensor W/Fan Control, App & Automation Using Arduino

App Automation (1)

App Automation (1)

Step 1: The Board & ShieldsThe Board Shields (1)

Wemos D1 Mini

11 digital input/output pins, all pins have interrupt/pwm/I2C/one-wire supported(except D0)

1 analog input(3.2V max input) a Micro USB connection

Compatible with Arduino

Compatible with nodemcu


Temperature: -20~60°C Humidity: 20-95%RH (±5%RH) It uses D1 and D2 of the WEMOS Board and is extremely popular. They tones of information and code already written for it.


The relay is a basic 5v relay and can switch up to 15A @ 120V I\

Step 2: Code!CODE 3 (2)

Get the latest version here:


  Download latest Blynk library here:
    https://github.com/blynkkk/blynk-library/releases/latest  Blynk is a platform with iOS and Android apps to control
  Arduino, Raspberry Pi and the likes over the Internet.
  You can easily build graphic interfaces for all your
  projects by simply dragging and dropping widgets.    Downloads, docs, tutorials: http://www.blynk.cc
    Sketch generator:           http://examples.blynk.cc
    Blynk community:            http://community.blynk.cc
    Social networks:            https://www.fb.com/blynkapp
                                http://twitter.com/blynk_app  Blynk library is licensed under MIT license
  This example code is in public domain. *************************************************************
  This example runs directly on ESP8266 chip.  Note: This requires ESP8266 support package:
    https://github.com/esp8266/Arduino  Please be sure to select the right ESP8266 module
  in the Tools -> Board menu!  Change WiFi ssid, pass, and Blynk auth token to run 🙂
  Feel free to apply it to any other example. It's simple!
 *************************************************************////////////1////////////* Comment this out to disable prints and save space */
#define BLYNK_PRINT Serial#include 
#include /////////////2/////////////
// You should get Auth Token in the Blynk App.
// Go to the Project Settings (nut icon).
char auth[] = "";// Your WiFi credentials.
// Set password to "" for open networks.
char ssid[] = "";
char pass[] = "";/////////////3/////////////
// Setting up the pin and DHT version
#define DHTTYPE DHT11   // DHT Shield uses DHT 11
#define DHTPIN D4       // DHT Shield uses pin D4
DHT dht(DHTPIN, DHTTYPE);// Set Colors of LEDs
/* Not currently used
//Widget Colors
#define BLYNK_Green     "#23C48E"
#define BLYNK_Blue      "#04C0F8"
#define BLYNK_Red       "#D3435C"
//Set up of the Humiditly LED & override LED 
//these are software LEDs in app
WidgetLED humLED(V1); 
WidgetLED overrideLED(V2);//this timer is used for the blynk app/server and to call data from the sensor
BlynkTimer timer;
//this timer is used to shut off the fan after a cer
SimpleTimer overrideShutOffTimer;/////////////4/////////////
//Sensor varables
float h = 0;
float t = 0;//Fan varables
int fanState = 0;
bool fanOverride = false;// countdown variables and timer
int CountdownRemain;
int CountdownTimer;/////////////5/////////////
// this funtion gets the data from the sensro and send it to the blynk server for you to see on the app
void sendSensor()
  h = dht.readHumidity();
  t = dht.readTemperature(true); // or dht.readTemperature(true) for Fahrenheit  if (isnan(h) || isnan(t)) {
    Serial.println("Failed to read from DHT sensor!");
  // You can send any value at any time.
  // Please don't send more that 10 values per second.
  int hAsInt = int(h); // converts to int removing unessisary decimal points
  int tAsInt = int(t);
  Blynk.virtualWrite(V5, hAsInt);
  Blynk.virtualWrite(V6, tAsInt);
// Fan Override Button
  int buttonState = param.asInt();
Serial.print("button pressed: ");
  if(buttonState == 1){
    fanState = 1;
    fanOverride = true;
    CountdownRemain = 600;
Serial.print("button State: ");
Serial.print(" fan State: ");
Serial.print(" fan override: ");
    fanState = 0;
    fanOverride = true;
    CountdownRemain = 600;
    overrideLED.on(); /*Debug 
Serial.print("button State: ");
Serial.print(" fan State: ");
Serial.print(" fan override: ");
void fanControl()
    if(h > 60 && fanOverride != true){
      fanState = 1; //ON
      Blynk.virtualWrite(V0, fanState);
Serial.print("over 60H, ");
    else if(h < 50 && fanOverride != true){
      fanState = 0; //OFF
      Blynk.virtualWrite(V0, fanState);
Serial.print("less than 50H, ");   
Serial.print("fan override, ");
    digitalWrite(D1, fanState);
/* Debug
Serial.print(" fan State: ");
Serial.print(" fan override: ");
void CountdownTimerFunction() {
Serial.print("countdown function called ");
  CountdownRemain--; // remove 1 every second
  Blynk.virtualWrite(V3, CountdownRemain);
  if (!CountdownRemain) { // check if CountdownRemain == 0/FALSE/LOW
    overrideShutOffTimer.disable(CountdownTimer); // if 0 stop timer
    CountdownRemain = 600;
    fanOverride = false;
Serial.println("counter if");
  } else {
Serial.println("counter else");
void setup()
  // Debug console
  pinMode(D1, OUTPUT); // Set the relay output up
  Blynk.begin(auth, ssid, pass);
   // Setup a function to be called every 5 seconds
  timer.setInterval(5000L, sendSensor);
  //Shut off the manual over ride
  CountdownTimer = overrideShutOffTimer.setInterval(1000L, CountdownTimerFunction); 
void loop()

Step 3: The Blynk APPThe Blynk APP (1)

Get the interface I used for this project by scanning the QR code with the Blynk APP. Check out how to do it here: http://docs.blynk.cc/#sharing

About Blynk (from there website):

Blynk is a Platform with iOS and Android apps to control Arduino, Raspberry Pi and the likes over the Internet.
It’s a digital dashboard where you can build a graphic interface for your project by simply dragging and dropping widgets. It’s really simple to set everything up and you’ll start tinkering in less than 5 mins. Blynk is not tied to some specific board or shield. Instead, it’s supporting hardware of your choice. Whether your Arduino or Raspberry Pi is linked to the Internet over Wi-Fi, Ethernet or this new ESP8266 chip, Blynk will get you online and ready for the Internet Of Your Things.

Step 4: Wiring It Up!Wiring It Up (2)

I had some Christmas light that had burned out and last year when all the LED were on sale I upgraded. I have a few sets of light laying around so I cannibalized the plugs from both ends. I spliced one of the wires together using solder and heat shrinkable tubing. The other wire I tined (solder) both ends but not together. Once it had cooled I trimmed them so that none of the metal would stick out. I then screwed them into the normal open (NO) and common (COM) terminal blocks.

I used some electrical tape to cover any of the exposed circuitry and leads.

I used a ziptie blocks and a Zip tie to secure everything to the compartment.

Step 5: InstallInstall

Install was really easy (for me).

As you can see my fan has 2 plugs under the plastic cover. One will be for the fan and the other will for usb power.

I plugged everything in and fed it through where the light once was.

Once I had it all wired in and powered up I gave it a test, and when it worked I installed the zip tie block.


Read more: WiFi Bathroom Humidity Sensor W/Fan Control, App & Automation

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