Matrix - One Touch Sensor

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1 Introduction

• The Matrix One_Touch_Sensor is a digital one capacitive touch key module. It uses the one key capacitive touch pad detector IC TTP223. It has a touch key with stable touching detection. It is designed for replacing traditional direct button key with diverse pad size.By default it outputs low. When a finger touches the touch key it outputs high.

2 Features

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

• Pin Description:

Pin	Description
S	GPIO
V	Supply Voltage 5V
G	Ground

3 Basic Device Operation

TTP223是一颗单键电容式触摸检测IC,它是利用电荷转移技术，通过检测压克力、塑料、玻璃、陶瓷、木材等绝缘介质上的按键电极与地的寄生电容电荷的微小改变来进行检测。

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-One_Touch_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:
Matrix-One_Touch_Sensor_nanopi_2

Connection Details:

Matrix-One_Touch_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-One_Touch_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:
Matrix-One_Touch_Sensor_NanoPC-T2

Connection Details:

Matrix-One_Touch_Sensor	NanoPC-T2
S	Pin15
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-gpio_int

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：

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

用手指按压模块时会检测到事件。

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-gpio_int，内容如下:

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]);
        }
    }
    sensorDeinit(devFD);
err:    
    system("rmmod "DRIVER_MODULE);
    return 0;
}

API说明参考维基：Matrix API reference manual