Matrix - Joystick

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1 Introduction

Joystick

• The matrix-joystick module is a two-axis stick module. It consists of two Sliding rheostats and one button. It has two analog outputs and one digital output. Its positional states can be measured as X and Y axis values as the calibrated resistance of the two potentiometers.
• When you move the joystick the sliding rheostats' resistance will change and the corresponding x/y values will change too. When you push the joystick the SW level will turn low.

2 Features

• X and Y axis, and one button
• 2.54mm spacing pin
• PCB dimension(mm): 24 X 32

• Pin Description:

Pin	Description
GND	Ground
5V	Supply Voltage 5V
SW	Button
X	X Axis
Y	Y Axis

3 Basic Device Operation

• It has two analog outputs and one digital output. The two analog outputs are measured as X and Y values as the calibrated resistance of the two potentiometers. The digital output is measured as Z value indicating whether or not the button is pressed.
  
• We extend all three outputs: X, Y and Z and users can use them easily.

4 硬件连接

模块Matrix-Joystick输出的是模拟信号，需要使用ADC转换模块Matrix-Analog_to_Digital_Converter将模拟信号转换为数字信号。
关于模块Matrix-Analog_to_Digital_Converter的使用方法可参考wiki：Matrix-Analog_to_Digital_Converter。

4.1 连接NanoPi M1

参考下图连接模块：

连接说明：

Matrix-Joystick
GND	NanoPi M1 Pin9
5V	NanoPi M1 Pin2
X	Matrix-Analog_to_Digital_Converter A1
Y	Matrix-Analog_to_Digital_Converter A2

4.2 连接NanoPi 2

参考下图连接模块：

连接说明：

Matrix-Joystick
GND	NanoPi 2 Pin9
5V	NanoPi 2 Pin2
X	Matrix-Analog_to_Digital_Converter A1
Y	Matrix-Analog_to_Digital_Converter A2

4.3 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：
Matrix_Joystick_nanopi_m2

连接说明：

Matrix-Joystick
GND	NanoPi M2 Pin9
5V	NanoPi M2 Pin2
X	Matrix-Analog_to_Digital_Converter A1
Y	Matrix-Analog_to_Digital_Converter A2

4.4 连接NanoPC-T2

参考下图连接模块：
Matrix_Joystick_NanoPC-T2

连接说明：

Matrix-Joystick
GND	NanoPC-T2 USB Host GND
5V	NanoPC-T2 USB Host 5V
X	Matrix-Analog_to_Digital_Converter A1
Y	Matrix-Analog_to_Digital_Converter A2

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-joystick

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：

x=1280 y=1280

拨动摇杆可以检测到x和y轴的变化。

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-joystick，内容如下:

int main(int argc, char ** argv)
{
    int i = 0;
    int x, y, board;
 
    x = y = 0;
    if ((board = boardInit()) < 0) {
        printf("Fail to init board\n");
        return -1;
    }
 
    system("modprobe "DRIVER_MODULE);
    signal(SIGINT, intHandler);
    for (i=0; i<PS2_READ_TIMES; i++) {
        if (pcf8591Read(1, &x) != -1 && pcf8591Read(2, &y) != -1) {
            printf("x=%4d y=%4d\n", x, y);
        }
    }
    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