Difference between revisions of "Matrix - Photoresistor"
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− | == | + | ==Compile & Run Test Program== |
− | + | 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> | ||
− | + | If your cloning is done successfully a "matrix" directory will be generated. | |
− | + | Compile and install Matrix: | |
<syntaxhighlight lang="bash"> | <syntaxhighlight lang="bash"> | ||
$ cd matrix | $ cd matrix | ||
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</syntaxhighlight> | </syntaxhighlight> | ||
− | + | Run test program: | |
<syntaxhighlight lang="bash"> | <syntaxhighlight lang="bash"> | ||
$ matrix-adc | $ matrix-adc | ||
</syntaxhighlight> | </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"> | <syntaxhighlight lang="bash"> | ||
The channel0 value is 2460 | The channel0 value is 2460 |
Revision as of 00:42, 22 June 2016
Contents
1 Introduction
- 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
- 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:
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:
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.
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
光照强度越强,读到的值越小。
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-analog_to_digital_converter,内容如下:
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; }
API说明参考维基:Matrix API reference manual