Matrix - LED

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1 Introduction

LED

LED

LED

Matrix-LED是一个简单的发光二极管模块。3-Pin 2.54mm排针，V接电源，G接地，S信号通过一个三极管放大控制LED的导通或关闭。您可以向S输出静态的高低电平信号，也可以输出变化的PWM信号，信号电平可以是3.3V或5V。当您向S输出高电平时LED以最大亮度发光，低电平就完全熄灭，可变占空比的PWM信号可以调节发光的亮度。

2 Features

• GPIO或PWM控制，3.3/5V电平，亮度通过PWM可调
• 体积小巧
• 2.54mm排针接口
• PCB尺寸（mm）：8x24

• Pin Description:

Pin	Description
S	GPIO
V	Supply Voltage 5V
G	Ground

3 Basic Device Operation

3-Pin 2.54mm排针，V接电源，G接地，S信号通过一个三极管放大控制LED的导通或关闭。您可以向S输出静态的高低电平信号，也可以输出变化的PWM信号，信号电平可以是3.3V或5V。当您向S输出高电平时LED以最大亮度发光，低电平就完全熄灭，可变占空比的PWM信号可以调节发光的亮度。

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 nanopi branch contains the matrix modules' code samples for the NanoPi
• The tiny4412 branch contains the matrix modules' code samples for the Tiny4412
• The 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 Connect to NanoPi

5.1 Preparations

Please install a Debian on a NanoPi and an appropriate cross compiler on a PC. Please refer to wiki:NanoPi
Compile a NanoPi kernel. Note: please use the kernel's source code from the nanopi-v4.1.y-matrix branch.

$ git clone https://github.com/friendlyarm/linux-4.x.y.git
$ cd linux-4.x.y
$ git checkout nanopi-v4.1.y-matrix
$ make nanopi_defconfig
$ touch .scmversion
$ make

5.2 Hardware Connection

Please refer to the following connection diagram to connect the Matrix-LED to the NanoPi

Connection Details:

Matrix-LED	NanoPi
S	Pin7
V	Pin4
G	Pin6

5.3 Compile Test Program

Please login the matrix hub and enter the nanopi branch

$ cd matrix
$ git checkout nanopi

Compile the matrix code

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

Note: please make sure to install the cross compiler "arm-linux-gcc-4.4.3" on your PC, which is used to compile files for the NanoPi-Debian.
Generated library files are under the "install/lib" directory. Applications are under the "install/usr/bin" directory. The test program for the "Matrix-LED" module is "matrix-led".

5.4 运行测试程序

拷贝库文件和测试程序到NanoPi的文件系统上

$ cp install/usr/bin/* nanopi_rootfs/usr/bin/
$ cp install/lib/* nanopi_rootfs/lib/ -d

然后启动NanoPi，在Debian的shell终端中执行如下命令运行模块Matrix-LED的测试程序

$ matrix-led

5.5 代码展示

int main(int argc, char ** argv) 
{
    int ledPin = GPIO_PIN1; 
    int i = 0;
    int ret = -1;
 
    if ((ret = exportGPIOPin(ledPin)) == -1) {   
        printf("exportGPIOPin(%d) failed\n", ledPin);
    }
    if ((ret = setGPIODirection(ledPin, GPIO_OUT)) == -1) {
        printf("setGPIODirection(%d) failed\n", ledPin);
    }
 
    for (i = 0; i < LED_BLINK_TIMES; i++) {
        if (i % 2) {
            ret = setGPIOValue(ledPin, GPIO_HIGH);
        } else {
            ret = setGPIOValue(ledPin, GPIO_LOW);
        }
        if (ret == -1) {
            printf("setGPIOValue(%d) failed\n", ledPin);
        }
        printf("LED blinking times %d\n", i);
        sleep(1);
    }
    unexportGPIOPin(ledPin);
    return 0;
}

6 与Tiny4412连接使用

6.1 准备工作

参考Tiny4412光盘里的《友善之臂Ubuntu使用手册》，在Tiny4412上运行UbuntuCore系统，然后在主机PC上安装并使用相应的编译器。
注意：只能使用Tiny4412SDK-1506的底板。

6.2 硬件连接

参考下图连接模块Matrix-LED和Tiny4412

连接说明：

Matrix-LED	Tiny4412
S	GPIO1 S
V	GPIO1 5V
G	GPIO1 GND

6.3 编译测试程序

进入Matrix代码仓库，切换到tiny4412分支

$ cd matrix
$ git checkout tiny4412

编译Matrix配件代码

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

注意：请确保你的主机PC当前使用的交叉编译器为Tiny4412-UbuntuCore配套的arm-linux-gnueabihf-gcc-4.7.3。
编译出来的库文件位于install/lib目录下，而测试程序则位于install/usr/bin目录下，模块Matrix-LED对应的测试程序为matrix-led。

6.4 运行测试程序

拷贝库文件和测试程序到Tiny4412的UbuntuCore的文件系统上

$ cp install/usr/bin/* tiny4412_rootfs/usr/bin/
$ cp install/lib/* tiny4412_rootfs/lib/ -d

然后启动Tiny4412，在UbuntuCore的shell终端中执行如下命令运行模块Matrix-LED的测试程序

$ matrix-led

6.5 代码展示

int main(int argc, char ** argv) 
{
    int ledPin = GPIO_PIN1; 
    int i = 0;
    int ret = -1;
 
    if ((ret = exportGPIOPin(ledPin)) == -1) {   
        printf("exportGPIOPin(%d) failed\n", ledPin);
    }
    if ((ret = setGPIODirection(ledPin, GPIO_OUT)) == -1) {
        printf("setGPIODirection(%d) failed\n", ledPin);
    }
 
    for (i = 0; i < LED_BLINK_TIMES; i++) {
        if (i % 2) {
            ret = setGPIOValue(ledPin, GPIO_HIGH);
        } else {
            ret = setGPIOValue(ledPin, GPIO_LOW);
        }
        if (ret == -1) {
            printf("setGPIOValue(%d) failed\n", ledPin);
        }
        printf("LED blinking times %d\n", i);
        sleep(1);
    }
    unexportGPIOPin(ledPin);
    return 0;
}