Paper Piano

Reference from the project of the same name by Electronics club, IIT Guwahati.

Hardware

• Arduino Uno

• Speaker(5W)

• 8* 1M ohm Resistors

• A4 sheet or any good paper

• Breadboard

• Graphite Pencil

Schematics

1. Connect 2nd DigitalPin to all the 8 resistors.

2. Connect pins 3-10 to another end of the resistors.

3. Connect pin 11 and GND pin to the buzzer.

4. Connect pins 3-11 to the paper shaded with graphite pencil.

Software(Library)

We use the capacitive sensing library to complete our project. Download the Zip file from the site. On your Arduino IDE select Sketch>Include Library>Add.ZIP Library>Select the file downloaded.

//include capacitive sensing library
#include<CapacitiveSensor.h>

Including the library required

//Capacitive Sensor Function
CapacitiveSensor cs_i_o = CapacitiveSensor(o,i);
//i=input,o=output pins.

In our Schematic pin2 is the output and pins 3-10 are inputs.

//calibration
cs_o_i.set_CS_Autocal_Millis(0xFFFFFFFF);

Calibration of the pins.

long total = cs_o_i.capacitiveSensor(sensitivity);

Set pin sensitivities and receive input.

if (total > threshold) tone(speakerPin, frequency)

Set the threshold value required to play particular tones strong enough, save the world:

#include <CapacitiveSensor.h>
 
#define speaker 11

// Set the Send Pin & Receive Pin.
CapacitiveSensor   cs_2_3 = CapacitiveSensor(2,3);        
CapacitiveSensor   cs_2_4 = CapacitiveSensor(2,4);         
CapacitiveSensor   cs_2_5 = CapacitiveSensor(2,5);     
CapacitiveSensor   cs_2_6 = CapacitiveSensor(2,6);     
CapacitiveSensor   cs_2_7 = CapacitiveSensor(2,7);      
CapacitiveSensor   cs_2_8 = CapacitiveSensor(2,8);         
CapacitiveSensor   cs_2_9 = CapacitiveSensor(2,9);  
CapacitiveSensor   cs_2_10 = CapacitiveSensor(2,10);  

void setup() 
{
  cs_2_6.set_CS_AutocaL_Millis(0xFFFFFFFF);     // turn off re calibration
  // Start serial
  Serial.begin(9600);
}


void loop() {
   // Set a timer.
  long start = millis();
  
  // Set the sensitivity of the sensors.
  long key1 =  cs_2_3.capacitiveSensor(3000);
  long key2 =  cs_2_4.capacitiveSensor(3000);
  long key3 =  cs_2_5.capacitiveSensor(3000);
  long key4 =  cs_2_6.capacitiveSensor(3000);
  long key5 =  cs_2_7.capacitiveSensor(3000);
  long key6 =  cs_2_8.capacitiveSensor(3000);
  long key7 =  cs_2_9.capacitiveSensor(3000);
  long key8 =  cs_2_10.capacitiveSensor(3000);
  int thres = 5000;

  Serial.print(millis() - start);        // check on performance in milliseconds
  Serial.print("\t");                    // tab character for debug windown spacing
  // Print outputs
  Serial.print(key1);                  
  Serial.print("\t");                   
  Serial.print(key2);   
  Serial.print("\t");                  
  Serial.print(key3);            
  Serial.print("\t");                   
  Serial.print(key4);                
  Serial.print("\t");                    
  Serial.print(key5);            
  Serial.print("\t");                
  Serial.print(key6);
  Serial.print("\t");                  
  Serial.print(key7);                                                    
  Serial.print("\t");
  Serial.println(key8);            
  
  // Produce tone on touching the capacitive sensor
  // Set the threshold for each key
  // visit https://www.arduino.cc/en/Tutorial/toneMelody for frequency settings
  if (key1 > thres) tone(speaker,131);   
  if (key2 > thres) tone(speaker,147);   
  if (key3 > thres) tone(speaker,165);
  if (key4 > thres) tone(speaker,175);
  if (key5 > thres) tone(speaker,196);
  if (key6 > thres) tone(speaker,220);
  if (key7 > thres) tone(speaker,247);
  if (key8 > thres) tone(speaker,262);
  
  // When none of them is touched no tone is produced.
  if (key1<=thres  &  key2<=thres  &  key3<=thres & key4<=thres  &  key5<=thres &  key6<=thres &  key7<=thres &  key8<=thres)
    noTone(speaker);
  delay(10); // arbitrary delay to limit data to serial port 
                               
}

Tuning

Paper clips can be used to connect the Arduino pins to the paper piano you designed. Turn on the system, check the serial monitor for the input values, and then set the threshold accordingly.

Link to Project by Electronics Club is Here