Difference between revisions of "Matrix - Pressure and Temperature Sensor"

From FriendlyELEC WiKi
Jump to: navigation, search
(与NanoPi 2连接使用)
Line 57: Line 57:
 
If this is successful a "matrix" directory will be generated, which will contain all the matrix modules' code samples.
 
If this is successful a "matrix" directory will be generated, which will contain all the matrix modules' code samples.
  
==与NanoPi 2连接使用==
+
==Connect to NanoPi 2==
===硬件连接===
+
===Hardware Connection===
参考下图连接模块Matrix-Pressure_and_Temperature_Sensor和NanoPi 2:<br>
+
Please refer to the following connection diagram to connect the Matrix-Pressure_and_Temperature_Sensor to the NanoPi 2:<br>
 
[[File:Matrix-Pressure_and_Temperature_Sensor_nanopi_2.jpg|frameless|600px|Matrix-Pressure_and_Temperature_Sensor_nanopi_2]]
 
[[File:Matrix-Pressure_and_Temperature_Sensor_nanopi_2.jpg|frameless|600px|Matrix-Pressure_and_Temperature_Sensor_nanopi_2]]
  
连接说明:
+
Connection Details:
 
{| class="wikitable"
 
{| class="wikitable"
 
|-
 
|-
Line 76: Line 76:
 
|}
 
|}
  
===编译测试程序===
+
===Compile Test Program===
进入Matrix代码仓库,切换到nanopi2分支
+
Please login the matrix hub and enter the nanopi2 branch
 
<syntaxhighlight lang="bash">
 
<syntaxhighlight lang="bash">
 
$ cd matrix
 
$ cd matrix
Line 83: Line 83:
 
</syntaxhighlight>
 
</syntaxhighlight>
  
编译Matrix配件代码
+
Compile the matrix code
 
<syntaxhighlight lang="bash">
 
<syntaxhighlight lang="bash">
 
$ make CROSS_COMPILE=arm-linux- clean
 
$ make CROSS_COMPILE=arm-linux- clean
Line 89: Line 89:
 
$ make CROSS_COMPILE=arm-linux- install
 
$ make CROSS_COMPILE=arm-linux- install
 
</syntaxhighlight>
 
</syntaxhighlight>
注意:请确保你的主机PC当前使用的交叉编译器为NanoPi 2配套的arm-linux-gcc-4.9.3。<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>
编译成功后库文件位于install/lib目录下,而测试程序则位于install/usr/bin目录下,模块Matrix-Pressure_and_Temperature_Sensor对应的测试程序为matrix-pressure_temp。<br>
+
Generated library files are under the "install/lib" directory. The test program is under the "install/usr/bin" directory.<br>
硬件驱动模块位于modules目录下,对应的驱动源码都包含在在NanoPi 2的Linux内核仓库里:https://github.com/friendlyarm/linux-3.4.y.git <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>
  
 
===运行测试程序===
 
===运行测试程序===

Revision as of 07:36, 26 February 2016

查看中文

1 Introduction

Matrix-Pressure and Temperature Sensor.png
  • The BMP180 is a high precision, ultra-low power small digital pressure sensor for consumer applications in mobile phones, PDAs, GPS navigation devices and outdoor equipments. With a low altitude noise of merely 0.25m at fast conversion time, the BMP180 offers superior performance. The I2C interface allows for easy system integration with a microcontroller.
  • The BMP180 is based on piezo-resistive technology for EMC robustness, high accuracy and linearity as well as long term stability.
  • The BMP180 consists of a piezo-resistive sensor, an analog to digital converter and a control unit with E2PROM and a serial I2C interface. The E2PROM has stored 176 bit of individual calibration data. This is used to compensate offset, temperature dependence and other parameters of the sensor.

2 Features

  • I2C,3.3V
  • Pressure data(16 to 19 bit)
  • Temperature data(16 bit)
  • PCB Dimension(mm): 16 x 16

Matrix-Pressure and Temperature Sensor PCB.png

  • Pin Description:
Pin Description
SDA I2C SDA
SCL I2C SCL
5V Supply Voltage 5V
GND Ground

3 Basic Device Operation

  • The mode (ultra low power, standard, high, ultra high resolution) can be selected by the variable oversampling_setting (0, 1, 2, 3) in the C code.
  • Calculation of true temperature and pressure in steps of 1Pa (= 0.01hPa = 0.01mbar) and temperature in steps of 0.1°C.
  • With the measured pressure p and the pressure at sea level p0 e.g. 1013.25hPa, the altitude in meters can be calculated with the international barometric formula: Matrix-Pressure and Temperature Sensor Calculat.png
  • With the measured pressure p and the absolute altitude the pressure at sea level can be calculated:

Matrix-Pressure and Temperature Sensor Calculat01.png Thus, a difference in altitude of ∆altitude = 10m corresponds to 1.2hPa pressure change at sea level.

4 Download Matrix Source Code

All the matrix modules' code samples are open source. They are maintained on GitHub - https://github.com/friendlyarm/matrix.git
Each branch in this hub contains the matrix modules' code samples for a board that the matrix modules can work with.

  • 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:
Install the git utility on a PC running Ubuntu14.04

$ sudo apt-get install git

Clone the matrix code from GitHub

$ git clone https://github.com/friendlyarm/matrix.git

If this is successful a "matrix" directory will be generated, which will contain all the matrix modules' code samples.

5 Connect to NanoPi 2

5.1 Hardware Connection

Please refer to the following connection diagram to connect the Matrix-Pressure_and_Temperature_Sensor to the NanoPi 2:
Matrix-Pressure_and_Temperature_Sensor_nanopi_2

Connection Details:

Matrix-Pressure_and_Temperature_Sensor_nanopi NanoPi 2
SDA Pin3
SCL Pin5
5V Pin4
GND Pin6

5.2 Compile Test Program

Please login the matrix hub and enter the nanopi2 branch

$ cd matrix
$ git checkout nanopi2

Compile the matrix code

$ make CROSS_COMPILE=arm-linux- clean
$ make CROSS_COMPILE=arm-linux-
$ make CROSS_COMPILE=arm-linux- install

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.
Generated library files are under the "install/lib" directory. The test program is under the "install/usr/bin" directory.
The modules are under the "modules" directory. The driver's source code is in github: https://github.com/friendlyarm/linux-3.4.y.git

5.3 运行测试程序

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。
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。

$ cp modules /media/rootfs/ -r
$ cp install/lib/* /media/rootfs/lib/ -d
$ cp install/usr/bin/* /media/rootfs/usr/bin/

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。

$ cd /modules
$ insmod bmp085.ko

运行模块Matrix-Pressure_and_Temperature_Sensor的测试程序。

$ matrix-pressure_temp

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。
运行效果如下:
matrix-pressure_temp_result

5.4 代码展示

int main(int argc, char ** argv) 
{ 
    int ret = -1;
    int bmpTemp = 0;
    int bmpPressure = 0;
    float altitude = 0;
 
    if ((ret = bmp180Read(BMP180_TEMP, &bmpTemp)) != -1) {
        printf("Get temperature : %.1f C\n", (float)bmpTemp / 10);
    } else {
        printf("Faided to get humidity\n");
    }
 
    if ((ret = bmp180Read(BMP180_PRESSURE, &bmpPressure)) != -1) {
        printf("Get pressure : %.2f hPa\n", (float)bmpPressure / 100);
    } else {
        printf("Faided to get pressure\n");
    }
 
    altitude = 44330 * ( 1 - pow( ((float)bmpPressure / 100 / 1013.25), (1/5.255) ) );
    printf("Get altitude : %.2f m\n", altitude);
    return 0;
}

6 与NanoPi连接使用

6.1 准备工作

在NanoPi上运行Debian系统,然后在主机PC上安装并使用相应的编译器,参考wiki: NanoPi & How to Build the Compiling Environment
注意: 只有使用nanopi-v4.1.y-matrix分支编译出来的内核才能配合Matrix配件正常工作。
下载NanoPi内核源代码并编译:

$ 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

编译好后的zImage位于内核源码arch/arm/boot/目录下,把该zImage替换掉NanoPi烧写文件sd-fuse_nanopi/prebuilt下的zImage,重新制作SD卡即可。

6.2 硬件连接

参考下图连接模块Matrix-Pressure_and_Temperature_Sensor和NanoPi:
Matrix-Pressure_and_Temperature_Sensor_nanopi

连接说明:

Matrix-Pressure_and_Temperature_Sensor_nanopi NanoPi
SDA Pin3
SCL Pin5
5V Pin4
GND Pin6

6.3 编译测试程序

进入Matrix代码仓库,切换到nanopi分支

$ cd matrix
$ git checkout nanopi

编译Matrix配件代码

$ make CROSS_COMPILE=arm-linux- clean
$ make CROSS_COMPILE=arm-linux-
$ make CROSS_COMPILE=arm-linux- install

注意:请确保你的主机PC当前使用的交叉编译器为NanoPi-Debian配套的arm-linux-gcc-4.4.3。
编译出来的库文件位于install/lib目录下,而测试程序则位于install/usr/bin目录下,模块Matrix-Pressure_and_Temperature_Sensor对应的测试程序为matrix-pressure_temp。

6.4 运行测试程序

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。
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的文件系统上。

$ cp modules /media/rootfs/ -r
$ cp install/lib/* /media/rootfs/lib/ -d
$ cp install/usr/bin/* /media/rootfs/usr/bin/

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。

$ cd /modules
$ insmod bmp085-i2c.ko

运行模块Matrix-Pressure_and_Temperature_Sensor的测试程序。

$ matrix-pressure_temp

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。

6.5 代码展示

int main(int argc, char ** argv) 
{ 
    int ret = -1;
    int bmpTemp = 0;
    int bmpPressure = 0;
    float altitude = 0;
 
    if ((ret = bmp180Read(BMP180_TEMP, &bmpTemp)) != -1) {
        printf("Get temperature : %.1f C\n", (float)bmpTemp / 10);
    } else {
        printf("Faided to get humidity\n");
    }
 
    if ((ret = bmp180Read(BMP180_PRESSURE, &bmpPressure)) != -1) {
        printf("Get pressure : %.2f hPa\n", (float)bmpPressure / 100);
    } else {
        printf("Faided to get pressure\n");
    }
 
    altitude = 44330 * ( 1 - pow( ((float)bmpPressure / 100 / 1013.25), (1/5.255) ) );
    printf("Get altitude : %.2f m\n", altitude);
    return 0;
}

7 与Tiny4412连接使用

8 与RaspberryPi连接使用

9 与Arduino连接使用

10 相关资料

BMP180.pdf

11 Update Log

11.1 Feb-24-2016

  • Added the whole English version