Published March 18, 2020 © CERN-OHL

Musical Soap Dispenser

Play your favorite tune for 20 seconds while you wash your hands.

IntermediateFull instructions provided3 hours1,838

Things used in this project

Hardware components

Microchip ATmega328

16 MHz Crystal

Multilayer Ceramic Capacitor, 20 pF

5V Power Supply

DFPlayer Mini

Resistor 1k ohm

Speaker: 0.25W, 8 ohms

Umbra Automatic Soap Dispenser

Micro SD Card

Software apps and online services

Patchr

I used the PCB design editor to design the final PCBs used in this project.

Audacity

I used this free, open source, audio editing software to create the 20 second clips.

Hand tools and fabrication machines

Soldering iron (generic)

Solder Wire, Lead Free

Bantam Tools Desktop PCB Milling Machine

Wire Stripper, STRIPAX

Wire Cutter / Stripper, 5.25 " Overall Length

Story

At the beginning of the COVID-19 outbreak I was given this handy automatic soap dispenser. With everyone coming up with different songs to sing while you wash your hands, I thought, there has to be a better way. I am a not a great singer and would rather hear the bands I love than try to match my voice to the Killers.

So, the Musical Soap Dispenser was born:

It’s a hacked Umbra Automatic Soap Dispenser with a speaker, MP3 circuit and micro controller. The Dispenser takes a microSD card with your favorite songs on it, each song is edited down to the chorus, playing 20 seconds while you wash your hands.

I have it loaded with three of my favorite hand washing songs:

1. Mr. Brightside by the Killers:

This is a re-enactment of my hand washing dance.

2. Africa by Toto:

3. Since You've Been Gone by Kelly Clarkson:

If you don't have an automatic soap dispenser, you can still build this, hop down to "Helpful Resources" to learn more.

Circuit Schematic

To build the circuit, use the following hookup guide:

I always suggest building it on a breadboard first, especially if you intend to design your own PCB. If you plan to just manufacture the PCBs using the Gerber files below, you can skip this step.

Putting It Together

With your PCBs in hand it's time to assemble your dispenser. I've built a diagram that should help with part placement and attaching to the soap dispenser.

Software

I'll be the first to admit I am not the greatest software developer. If anyone has suggestions here, I am totally open to comments/edits. I followed this tutorial by Nick Koumaris: http://educ8s.tv/arduino-mp3-player/. I ended up stripping it down significantly so that when you trigger the motion sensor on the dispenser you play the next song. After that song is finished, the song is paused.

The easiest way to program the Musical Soap Dispenser is to place your ATmega328p directly into an Arduino Uno, uploading the software, then removing the ATmega and placing it in the circuit.

Helpful Resources

Uploading new MP3s to your SD Card: https://wiki.dfrobot.com/DFPlayer_Mini_SKU_DFR0299#target_6

DFPlayer Mini Specs: https://wiki.dfrobot.com/DFPlayer_Mini_SKU_DFR0299#target_0

No Automatic Soap Dispenser?

Attach a limit switch or momentary button to the Soap Dispenser Data Line and Soap Dispenser Ground Line on the main controller board. Place the limit switch underneath the lip of the soap plunger so every time you press the plunger down it presses the button/limit switch!

Code

Musical Soap Dispenser

//Musical Soap Dispenser//
//Hardware by: Eric Schneider, 2020
//Adapted from Nick Koumaris' Arduino MP3 Player Tutorial//
/////////// http://educ8s.tv/arduino-mp3-player/ //////////


#include "SoftwareSerial.h"
SoftwareSerial mySerial (10,11); //Digital pins on ATmega328p
# define Start_Byte 0x7E
# define Version_Byte 0xFF
# define Command_Length 0x06
# define End_Byte 0xEF
# define Acknowledge 0x00 //Returns info with command 0x41 [0x01: info, 0x00: no info]

# define ACTIVATED HIGH

int buttonNext = 2; //Automatic Soap Dispenser Data Pin <--> ATmega328p
int buttonPause = 3; //DFPlayer Busy Pin <--> ATmega328p
boolean isPlaying = false;

void setup () {

  pinMode(buttonPause, INPUT);
  digitalWrite(buttonPause, LOW);
  pinMode(buttonNext, INPUT);
  digitalWrite(buttonNext, LOW);

  mySerial.begin (9600);
  delay(1000);
  isPlaying = true;
}

void loop () {
  if (digitalRead(buttonNext) == HIGH)
  {
    if (isPlaying)
    {
      playNext();
    }
    else if (digitalRead(buttonPause) == HIGH)
    {
      if (isPlaying)
      {
        pause();
        isPlaying = false;
        //delay(10000);
      } else
      {
        isPlaying = true;
        play();
      }
    }
  }
}

void playFirst()
{
  execute_CMD(0x3F, 0, 0);
  delay(500);
  setVolume(30);
  delay(500);
  execute_CMD(0x11, 0, 1);
  delay(500);
}

void pause()
{
  execute_CMD(0x0E, 0, 0);
  delay(500);
}

void play()
{
  execute_CMD(0x0D, 0, 1);
  delay(500);
}

void playNext()
{
  execute_CMD(0x01, 0, 1);
  delay(500);
}

void setVolume(int volume)
{
  execute_CMD(0x06, 0, volume); // Set the volume (0x00~0x30)
  delay(2000);
}

void execute_CMD(byte CMD, byte Par1, byte Par2)
// Excecute the command and parameters
{
  // Calculate the checksum (2 bytes)
  word checksum = -(Version_Byte + Command_Length + CMD + Acknowledge + Par1 + Par2);
  // Build the command line
  byte Command_line[10] = { Start_Byte, Version_Byte, Command_Length, CMD, Acknowledge,
                            Par1, Par2, highByte(checksum), lowByte(checksum), End_Byte
                          };
  //Send the command line to the module
  for (byte k = 0; k < 10; k++)
  {
    mySerial.write( Command_line[k]);
  }
}