Matrix - Sound Sensor

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1 Introduction

Sound Sensor

• The Matrix-Sound_Sensor module is used to detect sound.
• The module has a variable resistor which can be used to control the threshold value of a sound level. Only when a sound level's value is greater than this threshold the module can detect it. Turning clockwise increases this threshold value. Turning anticlockwise decreases this value.
• By default this module's output level is high. When it detects sound signals its output level will turn low. When sound signals are not detected its output will turn high again without time delay.

2 Features

• Variable threshold value
• 2.54mm spacing pin interface
• PCB dimension (mm): 16 x 24

• Pin Description:

Pin	Description
S	GPIO
V	Supply Voltage 5V
G	Ground

3 Basic Device Operation

• 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.
• This sound sensor functions like a microphone which receives sound waves and convert them to images which show the sound waves' vibration. When it receives a sound wave it will output 1 but cannot measure its strength.

4 Download Matrix Source Code

All the matrix modules' code samples are open source. They are maintained on GitHub - git://github.com/friendlyarm/matrix.git
Each branch in this hub contains the matrix modules' code samples for a board that the matrix modules can work with.

• The nanopi branch contains the matrix modules' code samples for the NanoPi
• The tiny4412 branch contains the matrix modules' code samples for the Tiny4412
• The raspberrypi branch contains the matrix modules' code samples for the RaspberryPi

Please follow the steps below to get the source code:
Install the git utility on a PC running Ubuntu14.04

$ sudo apt-get install git

Clone the matrix code from GitHub

$ git clone git://github.com/friendlyarm/matrix.git

If this is successful a "matrix" directory will be generated, which will contain all the matrix modules' code samples.

5 Connect to NanoPi

5.1 Preparations

Please install a Debian on a NanoPi and an appropriate cross compiler on a PC. Please refer to wiki :NanoPi
Compile a NanoPi kernel. Note: please use the kernel's source code from the nanopi-v4.1.y-matrix branch.

$ git clone https://github.com/friendlyarm/linux-4.x.y.git
$ cd linux-4.x.y
$ git checkout nanopi-v4.1.y-matrix
$ make nanopi_defconfig
$ touch .scmversion
$ make

5.2 Hardware Connection

Please refer to the following connection diagram to connect the Matrix-Sound_Sensor to the NanoPi

Connection Details:

Matrix-Sound_Sensor	NanoPi
S	Pin7
V	Pin4
G	Pin6

5.3 Compile Test Program

Please login the matrix hub and enter the nanopi branch

$ cd matrix
$ git checkout nanopi

Compile the matrix code

$ make CROSS_COMPILE=arm-linux- clean
$ make CROSS_COMPILE=arm-linux-
$ make CROSS_COMPILE=arm-linux- install

Note: please make sure to install the cross compiler "arm-linux-gcc-4.4.3" on your PC, which is used to compile files for the NanoPi-Debian.
Generated library files are under the "install/lib" directory. Applications are under the "install/usr/bin" directory. The test program for the "Matrix-Sound_Sensor" module is "matrix-sound_sensor".

5.4 Run Test Program

Please copy the library files and test program to the NanoPi

$ cp install/usr/bin/* nanopi_rootfs/usr/bin/
$ cp install/lib/* nanopi_rootfs/lib/ -d

Power on the NanoPi and run the following command in Debian's terminal

$ matrix-sound_sensor

5.5 Code Sample

static struct sensor sound[] = {
        {
                GPIO_PIN1,
                IRQ_TYPE_EDGE_BOTH,
        }
};
 
int main(void)
{
    int i;
    int retSize = -1;
    char value[ARRAY_SIZE(sound)];
    int devFD = -1;
    if ((devFD =sensorInit(sound, ARRAY_SIZE(sound))) == -1) {
        printf("Fail to init sensor\n");
        return -1;
    }
 
    if (( retSize = sensorRead(devFD, value, ARRAY_SIZE(sound)) ) == -1) {
        printf("Fail to read sensors\n");
    }
    if (retSize > 0) {
        i = 0;
        for(i=0; i<retSize; i++)
        {
            printf("sound[%d]:%d\n", i, value[i]);
        }
        printf("\n");
    }
    sensorDeinit(devFD);
    return 0;
}

6 Connect to Tiny4412

6.1 Preparations

Please refer to the Tiny4412's user's manual to install a UbuntuCore on the Tiny4412 and install an appropriate cross compiler on a PC.
Note: only the Tiny4412SDK-1506 carrier board can work with this module.

6.2 Hardware Connection

Please refer to the following diagram to connect the Matrix-Sound_Sensor to the Tiny4412

Connection Details:

Matrix-Sound_Sensor	Tiny4412
S	GPIO1 S
V	GPIO1 5V
G	GPIO1 GND

6.3 Compile Test Program

Please login the Matrix hub and enter the matrix-tiny4412 branch

$ cd matrix
$ git checkout tiny4412

Compile the matrix code

$ make CROSS_COMPILE=arm-linux-gnueabihf- clean
$ make CROSS_COMPILE=arm-linux-gnueabihf-
$ make CROSS_COMPILE=arm-linux-gnueabihf- install

Note: please make sure to install the cross compiler "arm-linux-gnueabihf-gcc-4.7.3" on your PC, which is used to compile files for the Tiny4412-UbuntuCore.
Generated library files are under the "install/lib" directory. Applications are under the "install/usr/bin" directory. The test program for the "Matrix-Sound_Sensor" module is "matrix-sound_sensor".

6.4 Run Test Program

Please copy the library files and test program to the Tiny4412

$ cp install/usr/bin/* tiny4412_rootfs/usr/bin/
$ cp install/lib/* tiny4412_rootfs/lib/ -d

Power on the Tiny4412 and run the following command in UbuntuCore's terminal
Note: this module is not plug and play therefore before running the module please make sure it is connected to a Tiny4412.

$ matrix-sound_sensor

6.5 Code Sample

static struct sensor sound[] = {
        {
                GPIO_PIN1,
                IRQ_TYPE_EDGE_BOTH,
        }
};
 
int main(void)
{
    int i;
    int retSize = -1;
    char value[ARRAY_SIZE(sound)];
    int devFD = -1;
    if ((devFD =sensorInit(sound, ARRAY_SIZE(sound))) == -1) {
        printf("Fail to init sensor\n");
        return -1;
    }
 
    if (( retSize = sensorRead(devFD, value, ARRAY_SIZE(sound)) ) == -1) {
        printf("Fail to read sensors\n");
    }
    if (retSize > 0) {
        i = 0;
        for(i=0; i<retSize; i++)
        {
            printf("sound[%d]:%d\n", i, value[i]);
        }
        printf("\n");
    }
    sensorDeinit(devFD);
    return 0;
}