BakeBit - Sound Sensor

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1 Introduction

Sound Sensor

• The BakeBit - Sound Sensor is a sound detection module. The module contains an electret condenser microphone. Sound waves impinging on the diaphragm cause the capacitance between it and the back plate to change synchronously, this in turn induces an AC voltage on the back plate, which is amplified with LM358 as output.
• Its default output is high. When it detects a sound wave it will output low. When no sounds are detected it will output high.

2 Hardware Spec

• Standard 2.0mm 4-Pin BakeBit Interface

• Pin Description:

Pin	Description
GND	Ground
5V	5V Supply Voltage
NC	Not Connected
SIG	Signal

3 Code Sample:Sound Sensor

When this program runs if surrounding environment’s sounds reach a threshold value the LED will be turned on.

3.1 Hardware Setup

Connect the Sound Sensor module to the NanoHat-Hub's A0 and the LED module to the NanoHat-Hub's D5:

3.2 Source Code

import time
import bakebit
 
# Connect the BakeBit Sound Sensor to analog port A0
# SIG,NC,VCC,GND
sound_sensor = 0
 
# Connect the BakeBit LED to digital port D5
# SIG,NC,VCC,GND
led = 5
 
bakebit.pinMode(sound_sensor,"INPUT")
bakebit.pinMode(led,"OUTPUT")
 
# The threshold to turn the led on 400.00 * 5 / 1024 = 1.95v
threshold_value = 400
 
while True:
    try:
        # Read the sound level
        sensor_value = bakebit.analogRead(sound_sensor)
 
        # If loud, illuminate LED, otherwise dim
        if sensor_value > threshold_value:
            bakebit.digitalWrite(led,1)
        else:
            bakebit.digitalWrite(led,0)
 
        print("sensor_value = %d" %sensor_value)
        time.sleep(.2)
 
    except IOError:
        print ("Error")

Github

3.3 Run Code Sample

Before you run the code sample you need to follow the steps in bakebit tutorial to install the BakeBit package.
Enter the "BakeBit/Software/Python" directory and run the "bakebit_sound_sensor.py" program:

cd ~/BakeBit/Software/Python
sudo python bakebit_sound_sensor.py

3.4 Observation

When you make some sounds to the sound sensor and if the sounds are big enough the LED will be turned on.

4 Resources

• [Schematic](BakeBit - Sound Sensor.pdf)
• [BakeBit Github Project Page](https://github.com/friendlyarm/BakeBit)
• [BakeBit Starter Kit User's Manual](http://wiki.friendlyarm.com/bakebit/bakebit_starter_kit_manual_en.pdf)

5 Update Log

5.1 December-14-2016

• Released English version

5.2 Jan-19-2016

• Renamed "NEO-Hub" to "NanoHat-Hub"