Difference between revisions of "Matrix - Potentiometer"

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[[Matrix - Potentiometer/zh|查看中文]]
 
[[Matrix - Potentiometer/zh|查看中文]]
 +
 +
==Introduction==
 +
[[File:Potentiometer .png|thumb|Potentiometer]]
 +
*The Matrix-Potentiometer module is a Potentiometer module. It can be used in audio control, motion control, transducers, computation and etc.
 +
*3 Pin 2.54mm spacing pin header, V is supply voltage, G is ground and S is output analog signal. Users can convert output analog signals to digital signals via ADC conversion.
 +
*Output Voltage: 0 ~ Vcc
 +
 +
==Features==
 +
* GPIO
 +
* Small
 +
* 2.54mm spacing pin header
 +
* PCB Dimension(mm): 8 x 24
 +
[[File:Potentiometer.png | frameless|400px|Potentiometer_PCB]]
 +
 +
* Pin Description:
 +
{| class="wikitable"
 +
|-
 +
|Pin || Description
 +
|-
 +
|S    || Analog GPIO
 +
|-
 +
|V    || Supply Voltage 5V
 +
|-
 +
|G    || Ground
 +
|}
 +
 +
==Basic Device Operation==
 +
*A potentiometer is a three-terminal resistor with a sliding or rotating contact that forms an adjustable voltage divider.If only two terminals are used, one end and the wiper, it acts as a variable resistor or rheostat.
 +
*This module mainly contains a potentiometer where the resistance changes with changes between the contact and one end terminal.
 +
 +
 +
==Applications==
 +
The Matrix-Potentiometer 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/zh|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-Potentiometer_nanopi_m1.jpg|frameless|600px|Matrix-Potentiometer_nanopi_m1]]
 +
 +
Connection Details:
 +
{| class="wikitable"
 +
|-
 +
|Matrix-Potentiometer ||     
 +
|-
 +
|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-Potentiometer.jpg|frameless|600px|Matrix-Potentiometer]]
 +
 +
Connection Details:
 +
{| class="wikitable"
 +
|-
 +
|Matrix-Potentiometer ||     
 +
|-
 +
|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-Potentiometer_nanopi_m2.jpg|frameless|600px|Matrix-Potentiometer_nanopi_m2]]
 +
 +
Connection Details:
 +
{| class="wikitable"
 +
|-
 +
|Matrix-Potentiometer ||     
 +
|-
 +
|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-Potentiometer_NanoPC-T2.jpg|frameless|600px|Matrix-Potentiometer_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>
 +
 +
==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-analog_to_digital_converter". 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==
 +
 +
<!---
 +
==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>
 +
Each branch in this hub contains the matrix modules' code samples for a board that the matrix modules can work with.<br>
 +
* The matrix-nanopi branch contains the matrix modules' code samples for the NanoPi;
 +
* The matrix-nanopi2 branch contains the matrix modules' code samples for the NanoPi 2;
 +
* The matrix-tiny4412 branch contains the matrix modules' code samples for the Tiny4412;
 +
* The matrix-raspberrypi branch contains the matrix modules' code samples for the RaspberryPi
 +
 +
Please follow the steps below to get the source code:<br>
 +
Install the git utility on a PC running Ubuntu14.04<br>
 +
<syntaxhighlight lang="bash">
 +
$ sudo apt-get install git
 +
</syntaxhighlight>
 +
 +
Clone the matrix code from GitHub
 +
<syntaxhighlight lang="bash">
 +
$ git clone https://github.com/friendlyarm/matrix.git
 +
</syntaxhighlight>
 +
If this is successful a "matrix" directory will be generated, which will contain all the matrix modules' code samples.<br>
 +
 +
==Connect to NanoPi 2==
 +
===Hardware Connection===
 +
Please refer to the following connection diagram to connect the Matrix-Potentiometer to the NanoPi 2:<br>
 +
[[File:Matrix-Potentiometer.jpg|frameless|600px|Matrix-Potentiometer]]
 +
 +
Connection Details:
 +
{| class="wikitable"
 +
|-
 +
|Matrix-Analog_to_Digital_Converter || NanoPi 2     
 +
|-
 +
|SDA    || Pin3
 +
|-
 +
|SCL    || Pin5
 +
|-
 +
|5V    || Pin4
 +
|-
 +
|GND    || Pin6
 +
|}
 +
 +
{| class="wikitable"
 +
|-
 +
|Matrix-Potentiometer ||     
 +
|-
 +
|GND    || NanoPi 2 Pin9
 +
|-
 +
|5V    || NanoPi 2 Pin2
 +
|-
 +
|S      || Matrix-Analog_to_Digital_Converter A0
 +
|}
 +
This module's output signals are analog signals. You can use our Matrix-Analog_to_Digital_Converter to convert them to digital signals.<br>
 +
Please connect the Matrix-Analog_to_Digital_Converter to the NanoPi 2 and then connect Pin S of the Matrix-Photoresistor's pin header to Matrix-Analog_to_Digital_Converter's A0.<br>
 +
For more details about the Matrix-Analog_to_Digital_Converter module please refer to wiki: [[Matrix_-_Analog_to_Digital_Converter]].<br>
 +
 +
===Compile Test Program===
 +
Please login the matrix hub and enter the nanopi2 branch
 +
<syntaxhighlight lang="bash">
 +
$ cd matrix
 +
$ git checkout nanopi2
 +
</syntaxhighlight>
 +
 +
Compile the Matrix code
 +
<syntaxhighlight lang="bash">
 +
$ make CROSS_COMPILE=arm-linux- clean
 +
$ make CROSS_COMPILE=arm-linux-
 +
$ make CROSS_COMPILE=arm-linux- install
 +
</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>
 +
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>
 +
 +
===Run Test Program===
 +
Please insert a TF card which is flashed with Debian to a Linux host and mount its boot and rootfs sections.<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">
 +
$ cp modules /media/rootfs/ -r
 +
$ cp install/lib/* /media/rootfs/lib/ -d
 +
$ cp install/usr/bin/* /media/rootfs/usr/bin/
 +
</syntaxhighlight>
 +
 +
Insert this TF card to your NanoPi 2, power on and run the following commands to load the driver.<br>
 +
<syntaxhighlight lang="bash">
 +
$ cd /modules
 +
$ insmod pcf8591.ko
 +
</syntaxhighlight>
 +
 +
Please run the following command to test the Matrix-Potentiometer module.<br>
 +
<syntaxhighlight lang="bash">
 +
$ matrix-adc
 +
</syntaxhighlight>
 +
Here is what you should expect:<br>
 +
[[File:matrix-adc_result.png|frameless||matrix-adc_result]] <br>
 +
 +
===Code Sample===
 +
<syntaxhighlight lang="c">
 +
int main(int argc, char ** argv)
 +
{
 +
    int i = 0;
 +
    int value = 0;
 +
    int channel = 0;
 +
 +
    if (argc == 2) {
 +
        channel = atoi(argv[1]);
 +
    }
 +
   
 +
    for (i=0; i<ADC_READ_TIMES; i++) {
 +
        if (pcf8591Read(channel, &value) != -1) {
 +
            printf("channel%d value=%d\n", channel, value);
 +
        } else {
 +
            printf("Fail to get channel%d value\n", channel);       
 +
        }
 +
        usleep(10000);
 +
    }
 +
    return 0;
 +
}
 +
</syntaxhighlight>
 +
--->
 +
 +
==Update Log==
 +
===Feb-24-2016===
 +
* Added link to the Chinese version
 +
===June-23-2016===
 +
* Re-organized and simplified wiki

Latest revision as of 14:27, 23 June 2016

查看中文

1 Introduction

Potentiometer
  • The Matrix-Potentiometer module is a Potentiometer module. It can be used in audio control, motion control, transducers, computation and etc.
  • 3 Pin 2.54mm spacing pin header, V is supply voltage, G is ground and S is output analog signal. Users can convert output analog signals to digital signals via ADC conversion.
  • Output Voltage: 0 ~ Vcc

2 Features

  • GPIO
  • Small
  • 2.54mm spacing pin header
  • PCB Dimension(mm): 8 x 24

Potentiometer_PCB

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

3 Basic Device Operation

  • A potentiometer is a three-terminal resistor with a sliding or rotating contact that forms an adjustable voltage divider.If only two terminals are used, one end and the wiper, it acts as a variable resistor or rheostat.
  • This module mainly contains a potentiometer where the resistance changes with changes between the contact and one end terminal.


4 Applications

The Matrix-Potentiometer 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-Potentiometer_nanopi_m1

Connection Details:

Matrix-Potentiometer
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-Potentiometer

Connection Details:

Matrix-Potentiometer
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-Potentiometer_nanopi_m2

Connection Details:

Matrix-Potentiometer
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-Potentiometer_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

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-analog_to_digital_converter". 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 Feb-24-2016

  • Added link to the Chinese version

8.2 June-23-2016

  • Re-organized and simplified wiki
Retrieved from "https://wiki.friendlyelec.com/wiki/index.php?title=Matrix_-_Potentiometer&oldid=6233"