Sound Sensor with micro:bit

Step 1 The Module

• 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 micro:bit

  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.

Step 2 Connect module to breadboard

Step 3 Connect P1 to AO

Step 4 Connect GND to GND

Step 5 Connect 3.3V to +

Step 6 Connect P5 to DO

Step 7 Add a resistor

Step 8 Connect GND to LED (Negative lead)

Step 9 Connect P2 to resistor

Step 10 The MakeCode

let soundLevel = 0
basic.forever(function () {
    soundLevel = pins.analogReadPin(AnalogPin.P1)
    basic.showNumber(soundLevel)
    basic.pause(100)
})
basic.forever(function () {
    if (soundLevel >= 32) {
        pins.digitalWritePin(DigitalPin.P2, 1)
    } else {
        pins.digitalWritePin(DigitalPin.P2, 0)
    }
    basic.pause(100)
})

• Click on 'New Project'

• Add the following code in the Javascript interface.

Step 11 The code

const int sensorPin = 1; // analog input pin for sound sensor
const int ledPin = 2; // pin for LED
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);
  Serial.println (sensorValue, DEC);
  digitalWrite (ledPin, HIGH);
  delay (1000);
  digitalWrite (ledPin, LOW);
  delay (1000);
}

• We connected the analog pin (AO) of the sound sensor to Pin 1 on the micro:bit, therefore the value of int sensorPin is A1 here.

• We connected the positive leg of the LED to pin 2 of the micro:bit, so int ledPin is set to 2.

• We will also create a variable, 'sensorValue' to store the value coming from the sound sensor.

  • While the circuit has current flowing through it, the LED will blink on and off with a delay of 1 second in between. Feel free to change the delay value. Right now it is set at '1000' which is 1 second.

  • Serial.println (sensorValue, DEC);' outputs the analog value to the serial monitor

Step 12 Open Arduino IDE

• We can also use the Arduino IDE to program the micro:bit.

• Open up the Arduino IDE.

• If you have not already got it installed, please follow our previous guide on how to install and set up the Arduino IDE for the micro:bit!

Step 13 Serial monitor values

• Click on Tools > Serial monitor Now you can see the the output values you are getting in a quiet room.

Step 14 Making adjustments

• You can update the sound detection threshold level so that when a loud sound is made, the LED comes on. You can do so by changing '32' in 'sensorValue >= 32' to a higher value.

Step 15 Sound level goes above threshold

const int sensorPin = 1; // pin for sound sensor
const int ledPin = 2; // select the pin for the LED
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 >= 32){
    digitalWrite (ledPin, HIGH);
    }
  else{
    digitalWrite (ledPin, LOW);
  }
  Serial.println (sensorValue, DEC);
  delay(1000);
}

• The code has been updated so that when the sensorValue goes above or equal 32, the LED will light up. If not, the LED will not light up. Upload this sketch to the micro:bit.

Step 16 Upload the sketch

• Click on the upload button next to it to upload the sketch

• Click on the tick icon on the top left hand-corner to verify the code