Matrix - LED

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1 Introduction

LED

LED

LED

The Matrix-LED is an LED module with three 2.54 mm spacing pins: V(supply voltage),G(ground) and S(signal) which is connected to a triode to turn the LED on or off. You can write high or low, or PWN signals(3.3V or 5V) to S. When you write high to S the LED will turn on and become brightest. When you write low to S the LED will turn off. If you write PWM signals to S the LED's brightness will vary depending on the PWM's signal variances.

2 Features

• GPIO/PWM interface, 3.3/5V, PWM brightness control
• Small, easy to be used in various situations
• 2.54 mm spacing pin
• PCB Dimension(mm): 8 x 24

• Pin Description:

Pin	Description
S	GPIO
V	Supply Voltage 5V
G	Ground

3 Basic Device Operation

The module has three 2.54 mm spacing pins: V(supply voltage),G(ground) and S(signal) which is connected to a triode to turn the LED on or off. You can write high or low, or PWN signals(3.3V or 5V) to S. When you write high to S the LED will turn on and become brightest. When you write low to S the LED will turn off. If you write PWM signals to S the LED's brightness will vary depending on the PWM's signal variances.

4 Download Matrix Source Code

All the matrix modules' code samples are open source. They are maintained on GitHub - https://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 nanopi 2 branch contains the matrix modules' code samples for the NanoPi 2
• 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 https://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-LED和NanoPi 2：

连接说明：

Matrix-LED	NanoPi
S	Pin7
V	Pin4
G	Pin6

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-LED对应的测试程序为matrix-led。
硬件驱动模块位于modules目录下，对应的驱动源码都包含在在NanoPi 2的Linux内核仓库里：https://github.com/friendlyarm/linux-3.4.y.git

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-LED的测试程序。

$ matrix-led

运行效果如下：

可以看到LED在不停地闪烁。

5.4 代码展示

int main(int argc, char ** argv) 
{
    int ledPin = GPIO_PIN(7); 
    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 Connect to NanoPi

6.1 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

6.2 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

6.3 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".

6.4 Run Test Program

Please copy the library files and test program to the NanoPi

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

Power on the NanoPi and run the following command in Debian's terminal

$ matrix-led

6.5 Code Sample

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;
}

7 Connect to Tiny4412

7.1 Preparations

Please refer to the Tiny4412's user's manual to install a UbuntuCore on the Tiny4412 and install an appropriate cross compiler on a PC.
Note: only the Tiny4412SDK-1506 carrier board can work with this module.

7.2 Hardware Connection

Please refer to the following diagram to connect the Matrix-LED to the Tiny4412

Connection Details:

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

7.3 Compile Test Program

Please login the Matrix hub and enter the matrix-tiny4412 branch

$ cd matrix
$ git checkout tiny4412

Compile the matrix code

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

Note: please make sure to install the cross compiler "arm-linux-gnueabihf-gcc-4.7.3" on your PC, which is used to compile files for the Tiny4412-UbuntuCore.
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".

7.4 Run Test Program

Please copy the library files and test program to the Tiny4412

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

Power on the Tiny4412 and run the following command in UbuntuCore's terminal

$ matrix-led

7.5 Code Sample

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;
}