seeed studio Grove Reference manual

Grove - Loudness Sensor
Introduction
3.3V 5.0V Analog
The Grove - Loudness Sensor is designed to detect the loudness of environmental
sound. Based on amplifier LM2904 and a built-in microphone, it amplifies and filters
the high frequency signal that received from the microphone, and outputs a positive
envelop. This will make for Arduino’s signal acquisition. The output value depends on
the level of sound input. In order to avoid unnecessary signal disturbances, input
signal will go through two times’ filtering inside the module. Lastly, there is a screw
potentiometer that enables manual adjustments to the output gain.
Previous Version: v0.9b
Specifications
•Voltage ：3.5~10 VDC
•Working Frequency ：50~2000 Hz
•Sensitivity : -48~66 dB
•Signal-to-noise Ratio : >58 dB
•Output Signal range : Analog Signal (0-1023)
Tip
More details about Grove modules please refer to Grove System

Platforms Supported
Arduino Wio BeagleBone
Raspberry
Pi
LinkIt
ONE
Caution
The platforms mentioned above as supported is/are an indication of the module's hardware or theoritical compatibility. We only
provide software library or code examples for Arduino platform in most cases. It is not possible to provide software library /
demo code for all possible MCU platforms. Hence, users have to write their own software library.
Demonstration
With Arduino
This module uses the chip LM2904 to amplify the electronic signal produced by the
mini microphone. At last, you’ll get the analog-to-digital conversion value. Let’s try to
read the output value.
•As the picture on the below indicates, the Loudness sensor is connected to analog port
A0 of the Grove - Base Shield.
•Connect Arduino/Seeeduino to PC by using a USB cable.

•Copy and paste code below to a new Arduino sketch.
int val;
void setup()
{
Serial.begin(9600);
}
void loop()
{
analogRead(0);
delay(10);
val = analogRead(0);
Serial.println(val);
delay(200);
}
•Upload the code.
•Then open the serial monitor to observe the output results. There will be a significant
change when blow to the sensor.

The blue line is the original signal from microphone and the yellow is the sig pin of
Loudness Sensor. It is the original signal envelope that the module outputs. Here is
the test screenshot from the oscilloscope.
Blowing to the sensor:
Speaking to the sensor：
With Raspberry Pi
1.You should have a raspberry pi and a grovepi or grovepi+.
2.You should have completed configuring the development enviroment, otherwise
follow here.
3.Connection
•Plug the sensor to grovepi socket A0 by using a grove cable.

4.Navigate to the demos’ directory:
cd yourpath/GrovePi/Software/Python/
•To see the code
nano grove_loudness_sensor.py # "Ctrl+x" to exit #
import time
import grovepi
# Connect the Grove Loudness Sensor to analog port A0
# SIG,NC,VCC,GND
loudness_sensor = 0
while True:
try:
# Read the sound level
sensor_value = grovepi.analogRead(loudness_sensor)
print "sensor_value =", sensor_value
time.sleep(.5)
except IOError:
print "Error"
5.Run the demo.
sudo python grove_loudness_sensor.py