Introduction

The EagLED can be used with external components such as a sound sensor module. 

In this guide, create a sound-activated light-up accessory with the EagLED, a sound sensor module, conductive thread, and felt fabric.

Complete this simple guide and incorporate it into your next wearable electronic costume or accessory.
    • Sound is a type of energy made by vibrations. When we hear something, we are sensing the vibrations in the air. 

      Infrasound are waves below 20Hz and are very difficult for humans to hear. You may have also heard of the term, ultrasound, which are sound waves above 20,000 Hz (20kHz). In this guide, we're interested in sound waves in the hearing range of a human ear (20 to 20,000 Hz).

    • To create a sound-reactive device, we'll use a sound sensor module. A sound sensor module has a microphone, an amplifier and other on-board circuitry. Through the use of the microphone, the module detects audio signals and converts the sound signal into a small voltage or current proportional to the detected signal. However, a microphone alone is insufficient. This is because without an amplifier, it would only produce very small electrical signals. So, the signal is fed through the on-board amplifier.

    • This sound sensor module can provide a binary indication of the presence of sound as well as an analog representation of its amplitude. Let's take a closer look at the Sound Sensor Module.

      It has four pins:

      DO: Digital Output 

      3.3V  : This pin is marked as '+' on the module. We'll connect it to 3.3V on the EagLED.

      GND: In electronics, we define a point in a circuit to be a kind of zero volts or 0V reference point, on which to base all other voltage measurements. This point is called ground or GND.

      AO: Analog Output

    • Voltage is the difference in potential between two points. As it is difficult to talk about voltage without a reference point, we need another point to compare it to. 

    • Connect '+' on the LED to '#10' on the EagLED

    • Connect '-' on the LED to 'GND' on the EagLED

    • Connect Sound Sensor Module with EagLED: '+' to '3.3V'

    • Connect 'GND' to 'GND'

    • Connect 'AO' to '#A9'

  1. const int sensorPin = A9; // analog input pin for sound sensor
    const int ledPin = 10; // pin for LED
    const int threshold = 850;
    int sensorValue = 0; // variable to store the value coming from the sensor
    
    
    void setup ()
    {
      pinMode(sensorPin, INPUT);
      pinMode (ledPin, OUTPUT);
      Serial.begin (9600);
    }
    
    void loop ()
    {
      sensorValue = analogRead(sensorPin);
      if (sensorValue >= threshold){
        digitalWrite (ledPin, HIGH);
        }
      else{
        digitalWrite (ledPin, LOW);
      }
      Serial.println (sensorValue, DEC);
    }
    • Upload this sketch to the EagLED.

    • Open up the Serial Plotter:

      On the Arduino IDE, click Tools > Serial Plotter

    • Make sure the baud rate is set to '9600 baud' found at the bottom right corner of the Serial Plotter window.

    • With the sound sensor nearby, clap your hands or tap the table. You should see a changing analog value resembling waves with its peaks and troughs.

    • If the LED does not light up, adjust the threshold value in the sketch from before. As we're using the 'AO' pin on the sound sensor, it will output analog values ranging from 0 to 1023. 

      Decrease the threshold value to increase sensitivity i.e. from '850' to '650'
      Increase the threshold value to decrease sensitivity.  i.e. from '850' to '1000'.

    • Now that the prototype is complete, it's time to create the accessory out of fabric.
      For this guide, we will create an bracelet out of felt fabric, a material that is easy to use with conductive thread. Cut out a rectangular piece of felt fabric.

    • It's time to sew the components onto the fabric. To connect the sound sensor to the EagLED, we will solder wires directly to them: Connect the 'F' end of a M-F jumper wire to 'AO' on the sound sensor module, then solder the 'M' end to the EagLED's '#A9' pin

    • Connect 'F' end of a jumper wire to '+', and then solder the 'M' end to EagLED '3.3V'

    • Connect 'F' end of another jumper wire to '-' on sound sensor module, then solder other end to 'GND' on EagLED

    • Next, connect the LED to EagLED. Stitch a line of conductive thread from the '+' on the LED to '#10' on the EagLED. 

    • Stitch another line from '-' to 'GND'. 

    • Finally, connect a coin cell battery holder to make the project portable. Connect '+' to '3.3V' 

    • Connect '-' to 'GND'

    • To add more LEDs, connect:

        '+' sew tab on second LED to '#6' on the EagLED

    • Connect the third LED's '+' sew tab to '#12' on the EagLED.

    • Finally, they will all be connected to the same 'GND' pin on the EagLED. So, connect the '-' sew tabs of the second and third LED to '-' on the first LED.

    • Stitch both ends of the rectangular piece of fabric together to complete the bracelet.

  2. const int sensorPin = A9; // analog input pin for sound sensor
    const int ledPins[] = {6, 10, 12}; // pins for LEDs
    const int threshold = 850;
    int sensorValue = 0; // variable to store the value coming from the sensor
    int pinCount = 3; //the number of pins used (i.e. the length of the array)
    
    void setup ()
    {
      pinMode(sensorPin, INPUT);
      for (int thisPin = 0; thisPin < pinCount; thisPin++) {
        pinMode(ledPins[thisPin], OUTPUT);
      }
      Serial.begin (9600);
    }
    
    void loop ()
    {
      sensorValue = analogRead(sensorPin);
      if (sensorValue >= threshold) {
        for (int thisPin = 0; thisPin < pinCount; thisPin++) {
          digitalWrite(ledPins[thisPin], HIGH);
        }
      }
      else {
        for (int thisPin = 0; thisPin < pinCount; thisPin++) {
          digitalWrite(ledPins[thisPin], LOW);
        }
      }
      Serial.println (sensorValue, DEC);
    }
    • Upload this sketch to the EagLED.

    • Clap your hands or knock on the table, the LEDs should light up!