Seeed Grove User manual

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Grove - Loudness Sensor
Version：1.0
Release date：9/20/2015
Wiki: http://www.seeedstudio.com/wiki/Grove_-_Loudness_Sensor
Bazaar: http:/www.seeedstudio.com/depot/Grove-Loudness-Sensor-p-1382.html?cPath=25_128

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Document Revision History
Revision
Date
Author
Description
1.0
Sep 21, 2015
Victor.He
Create file

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Contents
Document Revision History···································································································2
1. Introduction ···················································································································2
2. Specifications ·················································································································3
3. Demonstration ···············································································································4
3.1 With Arduino····················································································································· 4
3.2 With Raspberry Pi ············································································································· 6
4. Resource·························································································································8

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Disclaimer
For physical injuries and possessions loss caused by those reasons which are not related to product quality,
such as operating without following manual guide, natural disasters or force majeure, we take no
responsibility for that.
Under the supervision of Seeed Technology Inc., this manual has been compiled and published which
covered the latest product description and specification. The content of this manual is subject to change
without notice.
Copyright
The design of this product (including software) and its accessories is under tutelage of laws. Any action to
violate relevant right of our product will be penalized through law. Please consciously observe relevant local
laws in the use of this product.

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1. Introduction
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.

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2. 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)

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3. Demonstration
3.1 With Arduino
This module uses the chip LM2904 to amplify the electronic signal produced by the mini microphone. At
last, you will 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 - Basic 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);

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}
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:

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Speak to the sensor：
3.2 With Raspberry Pi
1. You should have got a raspberry pi and a grovepi or grovepi+.
2. You should have completed configuring the development environment, 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)

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except IOError:
print "Error"
5. Run the demo.
sudo python grove_loudness_sensor.py

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4. Resource
Grove - Loudness Sensor Eagle File
Grove - loudness sensor pdf
LM2904DR Datasheet

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