Difference between revisions of "Matrix - Photoresistor"

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*The module has a photoresistor. The resistance of a photoresistor decreases with increasing incident light intensity; in other words, it exhibits photoconductivity.If incident light on a photoresistor exceeds a certain frequency, photons absorbed by the semiconductor give bound electrons enough energy to jump into the conduction band. The resulting free electrons (and their hole partners) conduct electricity, thereby lowering resistance.
 
*The module has a photoresistor. The resistance of a photoresistor decreases with increasing incident light intensity; in other words, it exhibits photoconductivity.If incident light on a photoresistor exceeds a certain frequency, photons absorbed by the semiconductor give bound electrons enough energy to jump into the conduction band. The resulting free electrons (and their hole partners) conduct electricity, thereby lowering resistance.
  
−
==硬件连接==
+
==Applications==
−
模块Matrix-Photoresistor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。<br>
+
The Matrix-Photoresistor module outputs analog signals which can be converted to digital signals through an ADC converter e.g. the Matrix-Analog_to_Digital_Converter module.<br>
−
关于模块Matrix-Analog_to_Digital_Converter的使用方法可参考wiki：[[Matrix_-_Analog_to_Digital_Converter/zh|Matrix-Analog_to_Digital_Converter]]。<br>
+
For more details about the Matrix-Analog_to_Digital_Converter module refer to wiki: [[Matrix_-_Analog_to_Digital_Converter]].<br>
  
−
===连接NanoPi M1===
+
===Connect to NanoPi M1===
−
参考下图连接模块：<br>
+
Refer to the following connection diagram to connect the module to the NanoPi M1:<br>
 
[[File:Matrix-Photoresistor_nanopi_m1.jpg|frameless|600px|Matrix-Photoresistor_nanopi_m1]]
 
[[File:Matrix-Photoresistor_nanopi_m1.jpg|frameless|600px|Matrix-Photoresistor_nanopi_m1]]
  
−
连接说明：
+
Connection Details:
 
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===连接NanoPi 2===
+
===Connect to NanoPi 2===
−
参考下图连接模块：<br>
+
Refer to the following connection diagram to connect the module to the NanoPi 2:<br>
 
[[File:Matrix-Photoresistor_nanopi_2.jpg|frameless|600px|Matrix-Photoresistor_nanopi_2]]
 
[[File:Matrix-Photoresistor_nanopi_2.jpg|frameless|600px|Matrix-Photoresistor_nanopi_2]]
  
−
连接说明：
+
Connection Details:
 
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===连接NanoPi M2 / NanoPi 2 Fire===
+
===Connect to 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。<br>
+
Refer to the following connection diagram to connect the module to the NanoPi M2/ NanoPi 2 Fire.<br>
−
参考下图连接模块：<br>
+
 
[[File:Matrix-Photoresistor_nanopi_m2.jpg|frameless|600px|Matrix-Photoresistor_nanopi_m2]]
 
[[File:Matrix-Photoresistor_nanopi_m2.jpg|frameless|600px|Matrix-Photoresistor_nanopi_m2]]
  
−
连接说明：
+
Connection Details:
 
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===连接NanoPC-T2===
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===Connect to NanoPC-T2===
−
参考下图连接模块：<br>
+
Refer to the following connection diagram to connect the module to the NanoPC-T2:<br>
 
[[File:Matrix-Photoresistor_NanoPC-T2.jpg|frameless|600px|Matrix-Photoresistor_NanoPC-T2]]
 
[[File:Matrix-Photoresistor_NanoPC-T2.jpg|frameless|600px|Matrix-Photoresistor_NanoPC-T2]]
  
−
连接说明：
+
Connection Details:
 
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==编译运行测试程序==
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==Compile & Run Test Program==
−
启动开发板并运行Debian系统，进入系统后克隆Matrix代码仓库：
+
Boot your ARM board with Debian and copy the matrix code:
 
<syntaxhighlight lang="bash">
 
<syntaxhighlight lang="bash">
 
$ apt-get update && apt-get install git
 
$ apt-get update && apt-get install git
 
$ git clone https://github.com/friendlyarm/matrix.git
 
$ git clone https://github.com/friendlyarm/matrix.git
 
</syntaxhighlight>
 
</syntaxhighlight>
−
克隆完成后会得到一个名为matrix的目录。
+
If your cloning is done successfully a "matrix" directory will be generated.
  
−
编译并安装Matrix：
+
Compile and install Matrix:
 
<syntaxhighlight lang="bash">
 
<syntaxhighlight lang="bash">
 
$ cd matrix
 
$ cd matrix
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</syntaxhighlight>
 
</syntaxhighlight>
  
−
运行测试程序：
+
Run test program:
 
<syntaxhighlight lang="bash">
 
<syntaxhighlight lang="bash">
 
$ matrix-adc
 
$ matrix-adc
 
</syntaxhighlight>
 
</syntaxhighlight>
−
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。<br>
+
Note: this module is not plug and play therefore before running the module please make sure it is connected to an ARM board.<br>
−
运行效果如下：<br>
+
Here is what you should observe:<br>
 
<syntaxhighlight lang="bash">
 
<syntaxhighlight lang="bash">
 
The channel0 value is 2460
 
The channel0 value is 2460
 
</syntaxhighlight>
 
</syntaxhighlight>
−
光照强度越强，读到的值越小。
+
The resistance of a photoresistor decreases with increasing incident light intensity.
  
−
==代码说明==
+
==Code Sample==
−
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-analog_to_digital_converter，内容如下:
+
This Matrix code sample can work with all the ARM boards mentioned in this module's wiki. The name of this code sample is "matrix-3_axis_digital_compass". Here is its source code:
 
<syntaxhighlight lang="c">
 
<syntaxhighlight lang="c">
 
int main(int argc, char ** argv)
 
int main(int argc, char ** argv)
Line 152: Line 151:
 
}
 
}
 
</syntaxhighlight>
 
</syntaxhighlight>
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API说明参考维基：[[Matrix API reference manual/zh|Matrix API reference manual]] <br>
+
For more details about this APIs called in this code sample refer to [[Matrix API reference manual]] <br>
  
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==相关资料==
+
==Resources==
 +
 
 +
==Update Log==
 +
===June-22-2016===
 +
* Created English wiki
  
 
<!---
 
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Latest revision as of 00:46, 22 June 2016

查看中文

1 Introduction

Photoresistor
  • The Matrix-Photoresistor is a photoresistor module. It has a 3 pin 2.54mm spacing pin-header of which V is supply voltage, G is ground and s is output analog signal. The output signal decreases with increasing incident light intensity. Users can convert its output analog signal to a digital signal via ADC conversion.
  • Output Voltage: 0 ~ Vcc

2 Features

  • GPIO 3.3/5V
  • Small
  • 2.54mm spacing pin-header
  • PCB Dimension(mm): 8 x 24

Photoresistor.PCB

  • Pin Description:
Pin Description
S Analog GPIO
V Supply Voltage 5V
G Ground

3 Basic Device Operation

  • The module has a photoresistor. The resistance of a photoresistor decreases with increasing incident light intensity; in other words, it exhibits photoconductivity.If incident light on a photoresistor exceeds a certain frequency, photons absorbed by the semiconductor give bound electrons enough energy to jump into the conduction band. The resulting free electrons (and their hole partners) conduct electricity, thereby lowering resistance.

4 Applications

The Matrix-Photoresistor module outputs analog signals which can be converted to digital signals through an ADC converter e.g. the Matrix-Analog_to_Digital_Converter module.
For more details about the Matrix-Analog_to_Digital_Converter module refer to wiki: Matrix_-_Analog_to_Digital_Converter.

4.1 Connect to NanoPi M1

Refer to the following connection diagram to connect the module to the NanoPi M1:
Matrix-Photoresistor_nanopi_m1

Connection Details:

Matrix-Photoresistor
GND NanoPi M1 Pin9
5V NanoPi M1 Pin2
S Matrix-Analog_to_Digital_Converter A0

4.2 Connect to NanoPi 2

Refer to the following connection diagram to connect the module to the NanoPi 2:
Matrix-Photoresistor_nanopi_2

Connection Details:

Matrix-Photoresistor
GND NanoPi 2 Pin9
5V NanoPi 2 Pin2
S Matrix-Analog_to_Digital_Converter A0

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.
Matrix-Photoresistor_nanopi_m2

Connection Details:

Matrix-Photoresistor
GND NanoPi M2 Pin9
5V NanoPi M2 Pin2
S Matrix-Analog_to_Digital_Converter A0

4.4 Connect to NanoPC-T2

Refer to the following connection diagram to connect the module to the NanoPC-T2:
Matrix-Photoresistor_NanoPC-T2

Connection Details:

Matrix-Potentiometer
GND NanoPC-T2 USB Host GND
5V NanoPC-T2 USB Host 5V
S Matrix-Analog_to_Digital_Converter A0

5 Compile & Run Test Program

Boot your ARM board with Debian and copy the matrix code: 

$ apt-get update && apt-get install git
$ git clone https://github.com/friendlyarm/matrix.git

If your cloning is done successfully a "matrix" directory will be generated.

Compile and install Matrix: 

$ cd matrix
$ make && make install

Run test program: 

$ matrix-adc

Note: this module is not plug and play therefore before running the module please make sure it is connected to an ARM board.
Here is what you should observe:

The channel0 value is 2460

The resistance of a photoresistor decreases with increasing incident light intensity.

6 Code Sample

This Matrix code sample can work with all the ARM boards mentioned in this module's wiki. The name of this code sample is "matrix-3_axis_digital_compass". Here is its source code: 

int main(int argc, char ** argv)
{
    int i = 0;
    int value = 0;
    int channel = 0;
 
    if (boardInit() < 0) {
        printf("Fail to init board\n");
        return -1;
    }
 
    if (argc == 2)
        channel = atoi(argv[1]);
    system("modprobe "DRIVER_MODULE);
    signal(SIGINT, intHandler);
    for (i=0; i<ADC_READ_TIMES; i++) {
        if (pcf8591Read(channel, &value) != -1) {
            printf("The channel%d value is %d\n", channel, value);
        } else {
            printf("Fail to get channel%d value\n", channel);
        }
    }
    system("rmmod "DRIVER_MODULE);
 
    return 0;
}

For more details about this APIs called in this code sample refer to Matrix API reference manual

7 Resources

8 Update Log

8.1 June-22-2016

  • Created English wiki


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