Difference between revisions of "Matrix - 3-Axis Digital Accelerometer"

Revision as of 06:20, 16 September 2015

查看中文

1 Introduction

3-Axis Digital Accelerometer

• This module measures the static acceleration of gravity in three axis x, y and z resulting from motion or shock.
• Its digital interface is IIC or SPI.
• It is integrated with an ADXL345 chip with high resolution (13-bit) measurement at ±2g, ±4g, ±8g and ±16g.
• The module is powered by 5V and converts 5V to 3.3V to ADXL345.

2 Features

• I2C, 3.3V
• 13-bit, up to +-16g
• 2.54mm spacing pin interface
• PCB dimension(mm): 16 x 32

• Pin Spec:
  

3 工作原理

• ADXL345 是一款小巧纤薄的低功耗三轴加速度计，可以对高达±16 g的加速度进行高分辨率（13 位）测量。数字输出数据为 16 位二进制补码格式，可通过SPI （3 线或 4 线）或者I2C数字接口访问。
• ADXL345 非常适合移动设备应用。它可以在倾斜检测应用中测量静态重力加速度，还可以测量运动或冲击导致的动态加速度。它具有高分辨率（4 mg/LSB），能够测量约 0.25°的倾角变化。
• 由于这里使用的是I2C通信方式，所以只简单的介绍I2C的工作原理，具体时序的实现可自行去查看芯片手册。ADXL345遵循UM1024 I2C-总线规格，它支持标准的数据传输模式（100KHz），并且支持快速传输模式（400KHz），采用I2C模式，需要把CS引脚上拉，I2C引脚无连接时，默认模式不存在。
• 这里采用I2C通信，接线方式如下图：

4 Download Matrix Source Code

Matrix family members' code samples are open source which are maintained at: git://github.com/friendlyarm/matrix.git
In this warehouse each branch represents an ARM board that this matrix member can work with

• matrix-nanopi includes code samples for Matrix members that can work with the NanoPi;
• matrix-tiny4412 includes code samples for Matrix members that can work with the Tiny4412;
• matrix-raspberrypi includes code samples for Matrix members that can work with the RaspberryPi;

Here are the steps for installing git on a PC running Ubuntu14.04

$ sudo apt-get install git

Clone Matrix code warehouse

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

If this is a success a matrix directory will be generated, which will contain all available Matrix code samples.

5 Connect to NanoPi

5.1 Preparations

You need to install a Debian on the NanoPi and have a PC which has an appropriate cross compiler ready. For details you can refer to wiki:NanoPi

5.2 Hardware Connection

Please refer to the following diagrams to connect "Matrix-3_Axis_Digital_Accelerometer" to the NanoPi

Connection Details:

5.3 Compile Test Program

Please login the Matrix git and enter the matrix-nanopi branch

$ cd matrix
$ git checkout matrix-nanopi

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-4.4.3" on your PC, which is used to compile files for the NanoPi-Debian.
Generated library files are under the "install/lib" directory. Applications are under the "install/usr/bin" directory. The test program for the "Matrix-3_Axis_Digital_Accelerometer" module is "matrix-3_axis_digital_accelerometer".

5.4 Run Test Program

Please copy the library files and test program to the NanoPi

$ cp install/usr/bin/* nanopi_rootfs/usr/bin/
$ cp install/lib/* nanopi_rootfs/lib/ -d

Power on the NanoPi and run the following command in Debian's terminal
Note: this module is not plug and play therefore before running the module please make sure it is connected to a NanoPi.

$ matrix-3_axis_digital_accelerometer

5.5 Code Sample

int main(int argc, char ** argv) 
{
    char position[BUF_SIZE];
    memset(position, 0, BUF_SIZE);
 
    if (adxl34xRead(position) > 0) {
        printf("Get position: %s", position);
    } else {
        printf("Fail to get position\n");        
    }
    return 0;
}

6 Connect to Tiny4412

6.1 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.
Note: only the Tiny4412SDK-1506 carrier board can work with this module.

6.2 Hardware Connection

Please refer to the following diagrams to connect the Matrix-3_Axis_Digital_Accelerometer to the Tiny4412

Connection Details:

6.3 Compile Test Program

Please login the Matrix git and enter the matrix-tiny4412 branch

$ cd matrix
$ git checkout matrix-tiny4412

Compile the Matrix code

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

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.
Generated library files are under the "install/lib" directory. Applications are under the "install/usr/bin" directory. The test program for the "Matrix-3_Axis_Digital_Accelerometer" module is "matrix-3_axis_digital_accelerometer".

6.4 Run Test Program

Please copy the library files and test program to the Tiny4412

$ cp install/usr/bin/* tiny4412_rootfs/usr/bin/
$ cp install/lib/* tiny4412_rootfs/lib/ -d

Power on the Tiny4412 and run the following command in UbuntuCore's terminal
Note: this module is not plug and play therefore before running the module please make sure it is connected to a Tiny4412.

$ matrix-3_axis_digital_accelerometer

6.5 Code Sample

int main(int argc, char ** argv) 
{
    char position[BUF_SIZE];
    memset(position, 0, BUF_SIZE);
 
    if (adxl34xRead(position) > 0) {
        printf("Get position: %s", position);
    } else {
        printf("Fail to get position\n");        
    }
    return 0;
}

7 Connect to RaspberryPi

8 Connect to Arduino

9 Resources

ADXL345.pdf