Difference between revisions of "Matrix - Ball Rolling Switch"

Revision as of 10:13, 25 December 2015

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1 Introduction

BAll Rolling Switch

• The Matrix-Ball_Rolling_Switch module is a ball switch. Its electrical characteristics are very similar to a mercury switch's however a mercury switch is easily broken, oxidized, leaking and not environment-friendly. This ball switch prevents all these issues.
• The switch is free to move any angle and if that angle is between 15 degrees and 45 degrees a signal will be generated and used as an input to a Schmitt trigger.

2 Features

• GPIO
• Small
• 2.54 mm spacing pin header
• PCB Dimension(mm):16 x 16

• Pin Description:

3 Basic Device Operation

Please connect Pin V to a power supply, Pin G grounded and Pin S to a digital output. When you move the switch pushing the internal metal ball to connect the trigger point a high level signal will be generated and output to a Schmitt trigger which reverses this signal to output a low level signal. When you move the switch pushing the internal metal ball away from the trigger point a low level signal will be generated and output to a Schmitt trigger which reverses this signal to output a high level signal.

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 matrix-nanopi branch contains the matrix modules' code samples for the NanoPi
• The matrix-nanopi2 branch contains the matrix modules' code samples for the NanoPi 2
• The matrix-tiny4412 branch contains the matrix modules' code samples for the Tiny4412;
• The matrix-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 与NanoPi 2连接使用

5.1 硬件连接

参考下图连接模块Matrix-Ball_Rolling_Switch和NanoPi2：

连接说明：

5.2 编译测试程序

进入Matrix代码仓库，切换到nanopi2分支

$ cd matrix
$ git checkout nanopi2

编译Matrix配件代码

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

注意：请确保你的主机PC当前使用的交叉编译器为NanoPi 2配套的arm-linux-gcc-4.9.3。
编译成功后库文件位于install/lib目录下，而测试程序则位于install/usr/bin目录下，模块Matrix-Ball_Rolling_Switch对应的测试程序为matrix-ball_switch。

5.3 运行测试程序

将带有Debian系统的SD卡插入一台运行Linux的电脑，可以挂载SD卡上的boot和rootfs分区。
假设rootfs分区的挂载路径为/media/rootfs，执行以下命令将Matrix的硬件驱动、库文件和测试程序拷贝到NanoPi 2的文件系统上。

$ cp modules /media/rootfs/ -r
$ cp install/lib/* /media/rootfs/lib/ -d
$ cp install/usr/bin/* /media/rootfs/usr/bin/

将SD卡重新插入NanoPi 2，上电启动，在Debian的shell终端中执行以下命令运行模块Matrix-Ball_Rolling_Switch的测试程序。

$ matrix-ball_switch

运行效果如下：

将模块竖立起来，利用开关中的小珠的滚动，制造与金属端子的触碰或改变光线行进的路线，就能产生导通的效果。

5.4 代码展示

static struct sensor brSwitch[] = {
        {
                GPIO_PIN(7),
                IRQ_TYPE_EDGE_FALLING,
        }
};
 
int main(int argc, char ** argv)
{
    int i;
    int retSize = -1;
    char value[ARRAY_SIZE(brSwitch)];
    int devFD = -1;
 
    if (argc == 2) {
        brSwitch[0].pin = atoi(argv[1]);
    }
 
    printf("Using GPIO_PIN(%d)\n", brSwitch[0].pin);
    if ((devFD =sensorInit(brSwitch, ARRAY_SIZE(brSwitch))) == -1) {
        printf("Fail to init sensor\n");
        return -1;
    }
    printf("Lean the switch...\n");
    if ((retSize = sensorRead(devFD, value, ARRAY_SIZE(brSwitch))) == -1) {
        printf("Fail to read sensors\n");
    }
    if (retSize > 0) {
        i = 0;
        for (i=0; i<retSize; i++) {
            printf("Switch[%d]:%d\n", i, value[i]);
        }
    }
    sensorDeinit(devFD);
    return 0;
}