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.
  
 +
==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.<br>
 +
For more details about the Matrix-Analog_to_Digital_Converter module refer to wiki: [[Matrix_-_Analog_to_Digital_Converter]].<br>
 +
 +
===Connect to NanoPi M1===
 +
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]]
 +
 +
Connection Details:
 +
{| class="wikitable"
 +
|-
 +
|Matrix-Photoresistor ||     
 +
|-
 +
|GND    || NanoPi M1 Pin9
 +
|-
 +
|5V    || NanoPi M1 Pin2
 +
|-
 +
|S      || Matrix-Analog_to_Digital_Converter A0
 +
|}
 +
 +
===Connect to NanoPi 2===
 +
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]]
 +
 +
Connection Details:
 +
{| class="wikitable"
 +
|-
 +
|Matrix-Photoresistor ||     
 +
|-
 +
|GND    || NanoPi 2 Pin9
 +
|-
 +
|5V    || NanoPi 2 Pin2
 +
|-
 +
|S      || Matrix-Analog_to_Digital_Converter A0
 +
|}
 +
 +
===Connect to NanoPi M2 / NanoPi 2 Fire===
 +
Refer to the following connection diagram to connect the module to the NanoPi M2/ NanoPi 2 Fire.<br>
 +
[[File:Matrix-Photoresistor_nanopi_m2.jpg|frameless|600px|Matrix-Photoresistor_nanopi_m2]]
 +
 +
Connection Details:
 +
{| class="wikitable"
 +
|-
 +
|Matrix-Photoresistor ||     
 +
|-
 +
|GND    || NanoPi M2 Pin9
 +
|-
 +
|5V    || NanoPi M2 Pin2
 +
|-
 +
|S      || Matrix-Analog_to_Digital_Converter A0
 +
|}
 +
 +
===Connect to NanoPC-T2===
 +
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]]
 +
 +
Connection Details:
 +
{| class="wikitable"
 +
|-
 +
|Matrix-Potentiometer ||     
 +
|-
 +
|GND    || NanoPC-T2 USB Host GND
 +
|-
 +
|5V    || NanoPC-T2 USB Host 5V
 +
|-
 +
|S      || Matrix-Analog_to_Digital_Converter A0
 +
|}
 +
 +
==Compile & Run Test Program==
 +
Boot your ARM board with Debian and copy the matrix code:
 +
<syntaxhighlight lang="bash">
 +
$ apt-get update && apt-get install git
 +
$ git clone https://github.com/friendlyarm/matrix.git
 +
</syntaxhighlight>
 +
If your cloning is done successfully a "matrix" directory will be generated.
 +
 +
Compile and install Matrix:
 +
<syntaxhighlight lang="bash">
 +
$ cd matrix
 +
$ make && make install
 +
</syntaxhighlight>
 +
 +
Run test program:
 +
<syntaxhighlight lang="bash">
 +
$ matrix-adc
 +
</syntaxhighlight>
 +
Note: this module is not plug and play therefore before running the module please make sure it is connected to an ARM board.<br>
 +
Here is what you should observe:<br>
 +
<syntaxhighlight lang="bash">
 +
The channel0 value is 2460
 +
</syntaxhighlight>
 +
The resistance of a photoresistor decreases with increasing incident light intensity.
 +
 +
==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:
 +
<syntaxhighlight lang="c">
 +
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;
 +
}
 +
</syntaxhighlight>
 +
For more details about this APIs called in this code sample refer to [[Matrix API reference manual]] <br>
 +
 +
==Resources==
 +
 +
==Update Log==
 +
===June-22-2016===
 +
* Created English wiki
 +
 +
<!---
 
==Download Matrix Source Code==
 
==Download Matrix Source Code==
 
All the matrix modules' code samples are open source. They are maintained on GitHub: https://github.com/friendlyarm/matrix.git <br>
 
All the matrix modules' code samples are open source. They are maintained on GitHub: https://github.com/friendlyarm/matrix.git <br>
Line 95: Line 227:
 
</syntaxhighlight>
 
</syntaxhighlight>
 
Note: please make sure to install the cross compiler "arm-linux-gcc-4.9.3" on your PC, which is used to compile files for the NanoPi 2.<br>
 
Note: please make sure to install the cross compiler "arm-linux-gcc-4.9.3" on your PC, which is used to compile files for the NanoPi 2.<br>
−
Generated library files are under the "install/lib" directory. The test program is under the "install/usr/bin" directory.<br>
+
Generated library files are under the "install/lib" directory. The test program is under the "install/usr/bin" directory. Its test program is "matrix-adc"<br>
 
The modules are under the "modules" directory. Its driver's source code is in https://github.com/friendlyarm/linux-3.4.y.git <br>
 
The modules are under the "modules" directory. Its driver's source code is in https://github.com/friendlyarm/linux-3.4.y.git <br>
  
−
===运行测试程序===
+
===Run Test Program===
−
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。<br>
+
Please insert a TF card which is flashed with Debian to a Linux host and mount its boot and rootfs sections.<br>
−
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。<br>
+
We assume the rootfs is mounted to /media/rootfs then please run the following commands to copy the driver, library and test program to the card.<br>
 
<syntaxhighlight lang="bash">
 
<syntaxhighlight lang="bash">
 
$ cp modules /media/rootfs/ -r
 
$ cp modules /media/rootfs/ -r
Line 107: Line 239:
 
</syntaxhighlight>
 
</syntaxhighlight>
  
−
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加载硬件驱动。<br>
+
Insert this TF card to your NanoPi 2, power on and run the following commands to load the driver.<br>
 
<syntaxhighlight lang="bash">
 
<syntaxhighlight lang="bash">
 
$ cd /modules
 
$ cd /modules
Line 113: Line 245:
 
</syntaxhighlight>
 
</syntaxhighlight>
  
−
运行模块Matrix-Photoresistor的测试程序。<br>
+
Please run the following command to test the Matrix-Photoresistor module.<br>
 
<syntaxhighlight lang="bash">
 
<syntaxhighlight lang="bash">
 
$ matrix-adc
 
$ matrix-adc
 
</syntaxhighlight>
 
</syntaxhighlight>
−
运行效果如下：<br>
+
Here is what you should expect:<br>
 
[[File:matrix-adc_result.png|frameless||matrix-adc_result]] <br>
 
[[File:matrix-adc_result.png|frameless||matrix-adc_result]] <br>
  
−
===代码展示===
+
===Code Sample===
 
<syntaxhighlight lang="c">
 
<syntaxhighlight lang="c">
 
int main(int argc, char ** argv)
 
int main(int argc, char ** argv)
Line 143: Line 275:
 
}
 
}
 
</syntaxhighlight>
 
</syntaxhighlight>
 +
--->

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


Retrieved from "https://wiki.friendlyelec.com/wiki/index.php?title=Matrix_-_Photoresistor&oldid=6195"