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
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 Applications

4.1 Connect to NanoPi M1

Refer to the following connection diagram to connect the module to the NanoPi M1:

Connection Details:

Matrix-Sound_Sensor NanoPi M1
S Pin7
V Pin4
G Pin6

4.2 Connect to NanoPi 2

Refer to the following connection diagram to connect the module to the NanoPi 2:

Connection Details:

Matrix-Sound_Sensor NanoPi 2
S Pin7
V Pin4
G Pin6

4.3 Connect to NanoPi M2 / NanoPi 2 Fire

Refer to the following connection diagram to connect the module to the NanoPi M2/ NanoPi 2 Fire:

Connection Details:

Matrix-Sound_Sensor NanoPi M2
S Pin7
V Pin4
G Pin6

4.4 Connect to NanoPC-T2

Refer to the following connection diagram to connect the module to the NanoPC-T2:

Connection Details:

Matrix-Sound_Sensor NanoPC-T2
S Pin15
V Pin29
G Pin30

5 Compile & Run Test Program

Boot your ARM board with Debian and copy the matrix code:

$ apt-get update && apt-get install git
$ git clone

If your cloning is done successfully a "matrix" directory will be generated.

Compile and install Matrix:

$ cd matrix
$ make && make install

Run test program:

$ matrix-gpio_int

Note: this module is not plug and play therefore before running the module please make sure it is connected to an ARM board.
Here is what you should observe:

Waiting event...
Device[0] value is 1

When there is a sound an event will be triggered and detected.

6 Code Sample

This Matrix code sample can work with all the ARM boards mentioned in this module's wiki. The name of this code sample is "matrix-gpio_int". Here is its source code:

int main(int argc, char ** argv)
    int i, board;
    int retSize = -1;
    char value[ARRAY_SIZE(dev)];
    if ((board = boardInit()) < 0) {
        printf("Fail to init board\n");
        return -1;
    if (argc == 2)
        dev[0].pin = atoi(argv[1]);
    system("modprobe "DRIVER_MODULE);
    signal(SIGINT, intHandler);
    if (board == BOARD_NANOPI_T2)
        dev[0].pin = GPIO_PIN(15);
    printf("Use GPIO_PIN(%d)\n", dev[0].pin);
    if ((devFD =sensorInit(dev, ARRAY_SIZE(dev))) == -1) {
        printf("Fail to init sensor\n");
        goto err;
    printf("Waiting event...\n");
    if ((retSize = sensorRead(devFD, value, ARRAY_SIZE(dev))) == -1) {
        printf("Fail to read sensors\n");
    if (retSize > 0) {
        i = 0;
        for (i=0; i<retSize; i++) {
            printf("Device[%d] value is %d\n", i, value[i]);
    system("rmmod "DRIVER_MODULE);
    return 0;

For more details about this APIs called in this code sample refer to Matrix API reference manual

7 Resources

8 Update Log

8.1 Feb-23-2016

  • Added the description for "NanoPi 2 branch" in Section 4
  • Added Section 5: Connect to NanoPi 2

8.2 June-24-2016

  • Re-organized and simplified wiki