Matrix - Buzzer

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1 Introduction

Buzzer

• The Matrix-Buzzer is a passive buzzer. To drive this buzzer an oscillating source generating 2K - 5K square waves is needed.
• It can be used in electronic devices that need sound generators.

2 Features

• 3 PIN interface
• PCB dimension (mm): 16 x 24

• Pin Description:

Pin	Description
V	Supply Voltage 5V
G	Ground
S	PWM Input

3 Basic Device Operation

A passive buzzer will not tweet if DC signals are used; instead, you need to use square waves whose frequency is between 2K and 5K to drive it. If you use GPIO signals to drive it you need to pull the GPIO high first and then low to generate oscillation. The oscillation frequency is generated by the time in which GPIO signals turn from high to low. The buzzer will generate different sounds based on different frequencies.

4 硬件连接

4.1 连接NanoPi 2

参考下图连接模块：

连接说明：

Matrix-Buzzer	NanoPi 2
G	Pin6
V	Pin4
S	Pin22

4.2 连接NanoPi M2 / NanoPi 2 Fire

NanoPi M2和NanoPi 2 Fire的40 Pin引脚定义是一模一样的，所以它们操作Matrix配件的步骤是一样的，这里仅以NanoPi M2为例。
参考下图连接模块：

连接说明：

Matrix-Buzzer	NanoPi M2
G	Pin6
V	Pin4
S	Pin12

4.3 连接NanoPC-T2

参考下图连接模块：
Matrix-Buzzer_nanopc_t2

连接说明：

Matrix-Buzzer	NanoPC-T2
S	Pin23
V	Pin29
G	Pin30

5 编译运行测试程序

启动开发板并运行Debian系统，进入系统后克隆Matrix代码仓库：

$ apt-get update && apt-get install git
$ git clone https://github.com/friendlyarm/matrix.git

克隆完成后会得到一个名为matrix的目录。

编译并安装Matrix：

$ cd matrix
$ make && make install

运行测试程序：

$ matrix-pwm

注意：此模块并不支持热插拔，启动系统前需要确保硬件连接正确。
运行效果如下：

Using default config: channel=0 freq=1000Hz duty=500
Press enter to stop PWM

可以听到蜂鸣器鸣叫，占空比的范围为0-1000，键盘敲入回车键停止pwm输出。

6 代码说明

所有的开发板都共用一套Matrix代码，本模块的测试示例代码为matrix-pwm，内容如下:

int main(int argc, char ** argv)
{
    int Hz, duty, board;
 
    if ((board = boardInit()) < 0) {
        printf("Fail to init board\n");
        return -1;
    } 
 
    system("modprobe "DRIVER_MODULE);
    signal(SIGINT, intHandler);
    if (argc == 4) {
        // Usage:matrix-pwm channel freq duty[0~1000]
        pwm = atoi(argv[1]);
        Hz = atoi(argv[2]);
        duty = atoi(argv[3]);
    } else {
        Hz = 1000;
        duty = 500;
        printf("Using default config: channel=%d freq=%dHz duty=%d\n", pwm, Hz, duty);
    }
    if (PWMPlay(pwm, Hz, duty) == -1) {
        printf("Fail to output PWM\n");
    }  
    printf("Press enter to stop PWM\n");
    getchar();
    PWMStop(pwm);
    system("rmmod "DRIVER_MODULE);
 
    return 0;
}

API说明参考维基：Matrix API reference manual

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