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WiFi Doorbell with ESP32 and DFPlayer

DFRobot Feb 18 2019 1168

Things used in this project

Hardware components
Everything ESP ESP32S *2
Resistor 1k ohm
LED (generic)
SparkFun Pushbutton switch 12mm
2×8 cm PCB

DFRobot dfplayer *1

Hand tools and fabrication machines

Soldering iron (generic)
3D Printer (generic)


When we moved in our house this year, one of the first things we missed was a doorbell. There was a bell button at the gate, but since the whole building had been gutted down to the concrete nobody knew where the cable ended. When I found a cut-off electric cable in the basement, I suspected that it could be the one leading to the button. With a little help of my beloved multimeter I could confirm that assumption.

However, that lead to the next problem: Not only was the cable cut 2 cm off the wall, there was also no way to extend it to the first floor. And a doorbell in the basement is pretty much useless. There are WiFi solutions available that allow to put the bell in a different room, but they are expensive and need a 220 V hookup. So we settled with a wireless doorbell for the time being but it turned out not to be completely reliable, pretty ugly in comparison to the existing button and I did not like the battery based solution. So I set out to revive the old doorbell with the help of a microcontroller. Or two.

Parts List

The concept is easy: The first microcontroller detects the push on the button and sends a request to the second microcontroller via the home WiFi. That second microcontroller is connected to a speaker and plays a bell sound. Since I am pretty new to the Arduino world and wanted to keep things easy, I used Espressif ESP32 boards that have integrated WiFi. To make it even easier, I added a cheap MP3 player module.

  • 2× Espressif ESP32 development boards
  • DFPlayer MP3 module with a micro SD card. I used a doorbell sound from orangefreesounds.com
  • Speaker: Adafruit 3" (4Ω 3W ADA1314)
  • 2× 1 kΩ resistor
  • 2× 3.3 V LEDs to indicate operation (optional)
  • Pushbutton to trigger the bell from the sender (optional)
  • One 4×8 cm PCB and one 5×7 cm PCB


Not much to see here. Basically just throwing all the modules together. In the end I left out the LED on the speaker side. (It is still addressed in the code, though.)


I designed the two cases in Onshape, one for the sender and one for the speaker unit. The speaker case has a thin grid at the bottom and a little stand that is glued on in order to let the sound pass out.


Some additional photos can be found on the project page: http://tilman.de/projekte/wifi-doorbell/


While the sender does not much more than blinking the LED slightly differently depending on what it is doing, the speaker unit offers a bit more: It starts up a tiny web server that provides the interface for the sender and can also be used directly via the browser. It allows also to set the speaker volume:


 * Sources:
 * https://www.arduino.cc/en/Tutorial/Button
 * https://techtutorialsx.com/2017/05/19/esp32-http-get-requests/

#include <WiFi.h>
#include <HTTPClient.h>
const char* ssid     = "WiFi SSID";
const char* password = "WiFi password";
const char* bellUrl = "";

const int buttonPin = 21;    // the number of the pushbutton pin
const int ledPin =  23;      // the number of the LED pin
int buttonState = 0;

void setup() {

  btStop(); // turn off bluetooth

  pinMode(ledPin, OUTPUT);
  pinMode(buttonPin, INPUT);


void loop() {
  if ((WiFi.status() == WL_CONNECTED)) {

    buttonState = digitalRead(buttonPin);

    if (buttonState == HIGH) {
      digitalWrite(ledPin, HIGH);
      HTTPClient http;
      Serial.print("GET ");
      int httpCode = http.GET();
      if (httpCode > 0) {
          //String payload = http.getString();
      else {
        Serial.println("Error on HTTP request");
    else {
      digitalWrite(ledPin, LOW); 
  else {
    Serial.println("WiFi not connected!");
    digitalWrite(ledPin, HIGH);
    digitalWrite(ledPin, LOW);
    digitalWrite(ledPin, HIGH);
    digitalWrite(ledPin, LOW);

void connectWifi() {
  boolean ledStatus = false;
  Serial.print("Connecting to ");
  WiFi.begin(ssid, password);
  while (WiFi.status() != WL_CONNECTED) {
    ledStatus = !ledStatus;
    digitalWrite(ledPin, ledStatus);
  Serial.println("WiFi connected.");
  Serial.println("IP address: ");