Difference between revisions of "Matrix - Temperature Sensor"

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==Introduction==
 
==Introduction==
 
[[File:TemperatureSensor01.png|thumb|Temperature Sensor]]
 
[[File:TemperatureSensor01.png|thumb|Temperature Sensor]]
−
非常流行的TO-92封装的DS18B20。DSl8B20的电源可以由数据线本身提供而不需要外部电源，因为每一个DSl8B20在出厂时已经给定了唯一的序列号。DS18B20的测量范围是-55摄氏度到+125摄氏度，可选9-bit或12-bit，在-10摄氏度到+85摄氏度时可以精确到0.5度，采用一线协议通讯。我们把DS18B20的3个针脚全部引出，V对应电源引脚，G对应地引脚，S对应数据引脚。
+
* The matrix-temperature_sensor module is used to measure temperature.
−
We utilitze the DS18B20 in this module. Each DS18B20 is assigned a unique ID. Its temperature range is -55 degree Celsius to +125 degree Celsius.
+
* We utilitze the DS18B20 chip with the To-92 package in this module. Its unique 1-wire interface requires only 1 port pin for reading/writing. Power for reading, writing, and performing temperature conversions can be derived from the data line itself with no need for an external power source. The DS18B20 can be powered from its data line. Each DS18B20 is assigned a unique ID.
 +
* Its temperature range is -55 degree Celsius to +125 degree Celsius. The thermometer resolution is programmable from 9 to 12 bits. When the measured temperature is between -10 degree Celsius to +85 degree Celsius the accuracy can be at 0.5 degree. Among all three DS18B20 pins V is power, G is ground and S is data.
 +
 
 +
==Features==
 +
* -55 degree Celsius to +125 degree Celsius
 +
* One wire interface for communication
 +
* Tiny, easy to be deployed in various situations
 +
* 2.54mm spacing pin
 +
* PCB dimension(mm): 8 X 24
 +
[[File:temppcb.png|frameless|400px|Temperature Sensor PCB]]
 +
 
 +
 
 +
*Pin Description:
 +
{| class="wikitable"
 +
|-
 +
|Pin || Description
 +
|-
 +
|S    || GPIO
 +
|-
 +
|V    || Supply Voltage 5V
 +
|-
 +
|G    || Ground
 +
|}
 +
 
 +
==Basic Device Operation==
 +
The core functionality of the DS18B20 is its direct-to-digital temperature sensor. The resolution of the DS18B20 is configurable (9, 10, 11, or 12 bits), with 12-bit readings the factory default state. This
 +
equates to a temperature resolution of 0.5°C, 0.25°C, 0.125°C, or 0.0625°C. Following the issuance of the Convert T [44h] command, a temperature conversion is performed and the thermal data is stored in the scratchpad memory in a 16-bit, sign-extended two’s complement format. The temperature information can be retrieved over the 1-Wire interface by issuing a Read Scratchpad [BEh] command once the conversion has been performed. The data is transferred over the 1-Wire bus, LSB first. The MSB of the temperature register contains the “sign” (S) bit, denoting whether the temperature is positive or negative.
 +
 
 +
==Applications==
 +
===Connect to NanoPi M1===
 +
Refer to the following connection diagram to connect the module to the NanoPi M1:<br>
 +
[[File:Matrix-Temperature_Sensor_nanopi_m1.jpg|frameless|600px|Matrix-Temperature_Sensor_nanopi_m1]]
 +
 
 +
Connection Details:
 +
{| class="wikitable"
 +
|-
 +
|Matrix-Temperature_Sensor || NanoPi M1
 +
|-
 +
|S    || Pin7
 +
|-
 +
|V    || Pin4
 +
|-
 +
|G    || Pin6
 +
|}
 +
 
 +
===Connect to NanoPi 2===
 +
Refer to the following connection diagram to connect the module to the NanoPi 2:<br>
 +
[[File:Matrix-Temperature_Sensor_nanopi_2.jpg|frameless|600px|Matrix-Temperature_Sensor_nanopi_2]]
 +
 
 +
Connection Details:
 +
{| class="wikitable"
 +
|-
 +
|Matrix-Temperature_Sensor || NanoPi 2
 +
|-
 +
|S    || Pin7
 +
|-
 +
|V    || Pin4
 +
|-
 +
|G    || Pin6
 +
|}
 +
 
 +
===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-Temperature_Sensor_nanopi_m2.jpg|frameless|600px|Matrix-Temperature_Sensor_nanopi_m2]]
 +
 
 +
Connection Details:
 +
{| class="wikitable"
 +
|-
 +
|Matrix-Temperature_Sensor || NanoPi M2
 +
|-
 +
|S    || Pin7
 +
|-
 +
|V    || Pin4
 +
|-
 +
|G    || Pin6
 +
|}
 +
 
 +
===Connect to NanoPC-T2===
 +
Refer to the following connection diagram to connect the module to the NanoPC-T2:<br>
 +
[[File:Matrix-Temperature_Sensor_NanoPC-T2.jpg|frameless|600px|Matrix-Temperature_Sensor_NanoPC-T2]]
 +
 
 +
Connection Details:
 +
{| class="wikitable"
 +
|-
 +
|Matrix-Temperature_Sensor || NanoPC-T2
 +
|-
 +
|S    || Pin15
 +
|-
 +
|V    || Pin29
 +
|-
 +
|G    || Pin30
 +
|}
 +
 
 +
==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-temp_sensor
 +
</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 temperature is 27.312 C
 +
</syntaxhighlight>
 +
The module successfully read the environment's temperature.
 +
 
 +
==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-temperature_sensor". Here is its source code:
 +
<syntaxhighlight lang="c">
 +
int main(int argc, char ** argv)
 +
{
 +
    char temperature[BUF_SIZE], modStr[BUF_SIZE];
 +
    int board;
 +
    int pin=GPIO_PIN(7);
 +
   
 +
    if ((board = boardInit()) < 0) {
 +
        printf("Fail to init board\n");
 +
        return -1;
 +
    }
 +
    if (board == BOARD_NANOPI_T2)
 +
        pin = GPIO_PIN(15);
 +
   
 +
    if (argc == 2)
 +
        pin = atoi(argv[1]);
 +
    sprintf(modStr, "modprobe %s gpio=%d", TEMP_GPIO_DRIVER_MODULE, pintoGPIO(pin));
 +
    printf("%s\n", modStr);
 +
    system(modStr);
 +
    system("modprobe "TEMP_DRIVER_MODULE);
 +
    sleep(1);
 +
    memset(temperature, 0, BUF_SIZE);
 +
    if (ds18b20Read(temperature) > 0) {
 +
        printf("The temperature is %.3f C\n", atoi(temperature)/1000.0);
 +
    } else {
 +
        printf("Fail to get temperature\n");       
 +
    }
 +
    system("rmmod "TEMP_GPIO_DRIVER_MODULE);
 +
    system("rmmod "TEMP_DRIVER_MODULE);
 +
    return 0;
 +
}
 +
</syntaxhighlight>
 +
For more details about this APIs called in this code sample refer to [[Matrix API reference manual]] <br>
 +
 
 +
<!---
 +
==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 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:<br>
 +
Install the git utility on a PC running Ubuntu14.04
 +
<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.
 +
 
 +
 
 +
==Connect to NanoPi 2==
 +
===Hardware Connection===
 +
Please refer to the following connection diagram to connect the Matrix-Temperature_Sensor to the NanoPi 2:<br>
 +
[[File:Matrix-Temperature_Sensor_nanopi_2.jpg|frameless|600px|Matrix-Temperature_Sensor_nanopi_2]]
 +
 
 +
Connection Details:
 +
{| class="wikitable"
 +
|-
 +
|Matrix-Temperature Sensor || NanoPi 2
 +
|-
 +
|S  || Pin7
 +
|-
 +
|V  || Pin4
 +
|-
 +
|G  || Pin6
 +
|}
 +
 
 +
===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.<br>
 +
The modules are under the "modules" directory. The driver's source code is in github: 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 module, 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 w1-gpio.ko
 +
</syntaxhighlight>
 +
 
 +
Start the matrix-temp_sensor program.<br>
 +
<syntaxhighlight lang="bash">
 +
$ matrix-temp_sensor
 +
</syntaxhighlight>
 +
 
 +
Here is what you expect to observe:<br>
 +
[[File:matrix-temperature_sensor_result.png|frameless|600px|matrix-temperature_sensor_result]]
 +
 
 +
===Code Sample===
 +
<syntaxhighlight lang="c">
 +
int main(int argc, char ** argv)
 +
{
 +
    char temperature[BUF_SIZE];
 +
    memset(temperature, 0, BUF_SIZE);
 +
    if (ds18b20Read(temperature) > 0) {
 +
        printf("Temperature = %.3f C\n", atoi(temperature)/1000.0);
 +
    } else {
 +
        printf("Fail to get temperature\n");       
 +
    }
 +
    return 0;
 +
}
 +
</syntaxhighlight>
 +
 
 +
==Connect to NanoPi==
 +
===Preparations===
 +
Please install a Debian on a NanoPi and an appropriate cross compiler on a PC. Please refer to wiki: [[NanoPi/zh|NanoPi]] <br>
 +
Compile a NanoPi kernel. Note: please use the kernel's source code from the nanopi-v4.1.y-matrix branch<br>
 +
<syntaxhighlight lang="bash">
 +
$ 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
 +
</syntaxhighlight>
 +
 
 +
===Hardware Connection===
 +
Please refer to the following connection diagram to connect the Matrix-Temperature_Sensor module to the NanoPi <br>
 +
[[File:matrix-temperature_sensor_nanopi.jpg|frameless|600px|matrix-temperature_sensor_nanopi]]
 +
 
 +
Connection Details:
 +
{| class="wikitable"
 +
|-
 +
|Matrix-Temperature Sensor || NanoPi
 +
|-
 +
|S  || Pin7
 +
|-
 +
|V    || Pin4
 +
|-
 +
|G  || Pin6
 +
|}
 +
 
 +
===Compile Test Program===
 +
Please login the matrix hub and enter the nanopi branch
 +
<syntaxhighlight lang="bash">
 +
$ cd matrix
 +
$ git checkout nanopi
 +
</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-4.4.3" on your PC, which is used to compile files for the NanoPi-Debian.<br>
 +
Generated library files are under the "install/lib" directory. Applications are under the "install/usr/bin" directory. The test program for the "Matrix-Temperature_Sensor" module is "matrix-temperature_sensor".<br>
 +
 
 +
===Run Test Program===
 +
Please copy the library files and test program to the NanoPi
 +
<syntaxhighlight lang="bash">
 +
$ cp install/usr/bin/* nanopi_rootfs/usr/bin/
 +
$ cp install/lib/* nanopi_rootfs/lib/ -d
 +
</syntaxhighlight>
 +
 
 +
Power on the NanoPi and run the following command in Debian's terminal <br>
 +
Note: this module is not plug and play therefore before running the module please make sure it is connected to a NanoPi.
 +
<syntaxhighlight lang="bash">
 +
$ matrix-temperature_sensor
 +
</syntaxhighlight>
 +
 
 +
===Code Sample===
 +
<syntaxhighlight lang="c">
 +
int main(int argc, char ** argv)
 +
{
 +
    int devFD = -1;
 +
    int pin = GPIO_PIN1;
 +
    char *temperature = (char *) malloc(32);
 +
    memset(temperature, 0, 32);
 +
   
 +
    if (argc == 2) {
 +
        parseCmd(argc, argv, &pin);
 +
    } else {
 +
        printf("Using default pin GPIO_PIN1\n");
 +
    }
 +
 
 +
    if ((devFD = ds18b20Init(pin)) == -1) {
 +
        printf("Fail to init ds18b20\n");
 +
        return -1;
 +
    }
 +
    if (ds18b20Read(temperature) > 0) {
 +
        printf("Temperature = %s\n", temperature);
 +
    } else {
 +
        printf("Fail to get temperature\n");
 +
    }
 +
    free(temperature);
 +
    ds18b20DeInit(devFD);
 +
    return 0;
 +
}
 +
</syntaxhighlight>
 +
 
 +
==Connect to Tiny4412==
 +
===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.<br>
 +
Note: only the Tiny4412SDK-1506 carrier board can work with this module.
 +
 
 +
===Hardware Connection===
 +
Please refer to the following diagram to connect the Matrix-Temperature_Sensor to the Tiny4412 <br>
 +
[[File:matrix-temperature_sensor_tiny4412.jpg|frameless|600px|matrix-temperature_sensor_tiny4412]]
 +
 
 +
Connection Details:
 +
{| class="wikitable"
 +
|-
 +
|Matrix-Temperature Sensor || Tiny4412
 +
|-
 +
|S  || GPIO1 S
 +
|-
 +
|V    || GPIO1  5V
 +
|-
 +
|G  || GPIO1 GND
 +
|}
 +
 
 +
===Compile Test Program===
 +
Please login the Matrix hub and enter the matrix-tiny4412 branch
 +
<syntaxhighlight lang="bash">
 +
$ cd matrix
 +
$ git checkout tiny4412
 +
</syntaxhighlight>
 +
 
 +
Compile the matrix code
 +
<syntaxhighlight lang="bash">
 +
$ make CROSS_COMPILE=arm-linux-gnueabihf- clean
 +
$ make CROSS_COMPILE=arm-linux-gnueabihf-
 +
$ make CROSS_COMPILE=arm-linux-gnueabihf- install
 +
</syntaxhighlight>
 +
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.<br>
 +
Generated library files are under the "install/lib" directory. Applications are under the "install/usr/bin" directory. The test program for the "Matrix-Temperature_Sensor" module is "matrix-temperature_sensor".
 +
 
 +
===Run Test Program===
 +
Please copy the library files and test program to the Tiny4412
 +
<syntaxhighlight lang="bash">
 +
$ cp install/usr/bin/* tiny4412_rootfs/usr/bin/
 +
$ cp install/lib/* tiny4412_rootfs/lib/ -d
 +
</syntaxhighlight>
 +
 
 +
Power on the Tiny4412 and run the following command in UbuntuCore's terminal <br>
 +
Note: this module is not plug and play therefore before running the module please make sure it is connected to a Tiny4412.
 +
<syntaxhighlight lang="bash">
 +
$ matrix-temperature_sensor
 +
</syntaxhighlight>
 +
 
 +
===Code Sample===
 +
<syntaxhighlight lang="c">
 +
int main(int argc, char ** argv)
 +
{
 +
    int devFD = -1;
 +
    int pin = GPIO_PIN1;
 +
    char *temperature = (char *) malloc(32);
 +
    memset(temperature, 0, 32);
 +
   
 +
    if (argc == 2) {
 +
        parseCmd(argc, argv, &pin);
 +
    } else {
 +
        printf("Using default pin GPIO_PIN1\n");
 +
    }
 +
 
 +
    if ((devFD = ds18b20Init(pin)) == -1) {
 +
        printf("Fail to init ds18b20\n");
 +
        return -1;
 +
    }
 +
    if (ds18b20Read(temperature) > 0) {
 +
        printf("Temperature = %s\n", temperature);
 +
    } else {
 +
        printf("Fail to get temperature\n");
 +
    }
 +
    free(temperature);
 +
    ds18b20DeInit(devFD);
 +
    return 0;
 +
}
 +
</syntaxhighlight>
 +
 
 +
==Connect to RaspberryPi==
 +
 
 +
==Connect to Arduino==
 +
--->
 +
 
 +
==Resources==
 +
[http://datasheets.maximintegrated.com/en/ds/DS18B20.pdf DS18B20.pdf]
 +
 
 +
==Update Log==
 +
===Feb-23-2016===
 +
* Added the description for "NanoPi 2 branch" in Section 4
 +
* Added Section 5: Connect to NanoPi 2
 +
===June-24-2016===
 +
* Re-organized and simplified wiki
 +
 
 +
<!--
 +
==Introduction==
 +
[[File:TemperatureSensor01.png|thumb|Temperature Sensor]]
 +
We utilitze the DS18B20 in this module. The DS18B20 can be powered from its data line. Each DS18B20 is assigned a unique ID. Its temperature range is -55 degree Celsius to +125 degree Celsius. The thermometer resolution is programmable from 9 to 12 bits. When the measured temperature is between -10 degree Celsius to +85 degree Celsius the accuracy can be at 0.5 degree. It uses the unique 1-wire interface which requires only one port pin for communication. Among all three DS18B20 pins V is power, G is ground and S is data.
  
 
==Features==
 
==Features==
Line 108: Line 542:
  
 
==Resources==
 
==Resources==
 +
 +
-->

Latest revision as of 16:01, 24 June 2016

查看中文

1 Introduction

Temperature Sensor
  • The matrix-temperature_sensor module is used to measure temperature.
  • We utilitze the DS18B20 chip with the To-92 package in this module. Its unique 1-wire interface requires only 1 port pin for reading/writing. Power for reading, writing, and performing temperature conversions can be derived from the data line itself with no need for an external power source. The DS18B20 can be powered from its data line. Each DS18B20 is assigned a unique ID.
  • Its temperature range is -55 degree Celsius to +125 degree Celsius. The thermometer resolution is programmable from 9 to 12 bits. When the measured temperature is between -10 degree Celsius to +85 degree Celsius the accuracy can be at 0.5 degree. Among all three DS18B20 pins V is power, G is ground and S is data.

2 Features

  • -55 degree Celsius to +125 degree Celsius
  • One wire interface for communication
  • Tiny, easy to be deployed in various situations
  • 2.54mm spacing pin
  • PCB dimension(mm): 8 X 24

Temperature Sensor PCB


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

3 Basic Device Operation

The core functionality of the DS18B20 is its direct-to-digital temperature sensor. The resolution of the DS18B20 is configurable (9, 10, 11, or 12 bits), with 12-bit readings the factory default state. This equates to a temperature resolution of 0.5°C, 0.25°C, 0.125°C, or 0.0625°C. Following the issuance of the Convert T [44h] command, a temperature conversion is performed and the thermal data is stored in the scratchpad memory in a 16-bit, sign-extended two’s complement format. The temperature information can be retrieved over the 1-Wire interface by issuing a Read Scratchpad [BEh] command once the conversion has been performed. The data is transferred over the 1-Wire bus, LSB first. The MSB of the temperature register contains the “sign” (S) bit, denoting whether the temperature is positive or negative.

4 Applications

4.1 Connect to NanoPi M1

Refer to the following connection diagram to connect the module to the NanoPi M1:
Matrix-Temperature_Sensor_nanopi_m1

Connection Details:

Matrix-Temperature_Sensor NanoPi M1
S Pin7
V Pin4
G Pin6

4.2 Connect to NanoPi 2

Refer to the following connection diagram to connect the module to the NanoPi 2:
Matrix-Temperature_Sensor_nanopi_2

Connection Details:

Matrix-Temperature_Sensor NanoPi 2
S Pin7
V Pin4
G Pin6

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-Temperature_Sensor_nanopi_m2

Connection Details:

Matrix-Temperature_Sensor NanoPi M2
S Pin7
V Pin4
G Pin6

4.4 Connect to NanoPC-T2

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

Connection Details:

Matrix-Temperature_Sensor NanoPC-T2
S Pin15
V Pin29
G Pin30

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-temp_sensor

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 temperature is 27.312 C

The module successfully read the environment's temperature.

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-temperature_sensor". Here is its source code: 

int main(int argc, char ** argv)
{
    char temperature[BUF_SIZE], modStr[BUF_SIZE];
    int board;
    int pin=GPIO_PIN(7);
 
    if ((board = boardInit()) < 0) {
        printf("Fail to init board\n");
        return -1;
    }
    if (board == BOARD_NANOPI_T2)
        pin = GPIO_PIN(15);
 
    if (argc == 2)
        pin = atoi(argv[1]);
    sprintf(modStr, "modprobe %s gpio=%d", TEMP_GPIO_DRIVER_MODULE, pintoGPIO(pin));
    printf("%s\n", modStr);
    system(modStr);
    system("modprobe "TEMP_DRIVER_MODULE);
    sleep(1);
    memset(temperature, 0, BUF_SIZE);
    if (ds18b20Read(temperature) > 0) {
        printf("The temperature is %.3f C\n", atoi(temperature)/1000.0);
    } else {
        printf("Fail to get temperature\n");        
    }
    system("rmmod "TEMP_GPIO_DRIVER_MODULE);
    system("rmmod "TEMP_DRIVER_MODULE);
    return 0;
}

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


7 Resources

DS18B20.pdf

8 Update Log

8.1 Feb-23-2016

  • Added the description for "NanoPi 2 branch" in Section 4
  • Added Section 5: Connect to NanoPi 2

8.2 June-24-2016

  • Re-organized and simplified wiki


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