ADXL345 - Microcontroller No-OS Driver

Supported Devices

ADXL345

Evaluation Boards

Overview

The ADXL345 is a small, thin, low power, 3-axis accelerometer with high resolution (13-bit) measurement at up to ±16 g. Digital output data is formatted as 16-bit twos complement and is accessible through either a SPI (3- or 4-wire) or I2C digital interface. The ADXL345 is well suited for mobile device applications. It measures the static acceleration of gravity in tilt-sensing appli-cations, as well as dynamic acceleration resulting from motion or shock. Its high resolution (4 mg/LSB) enables measurement of inclination changes less than 1.0°.

The goal of this project (Microcontroller No-OS) is to be able to provide reference projects for lower end processors, which can't run Linux, or aren't running a specific operating system, to help those customers using microcontrollers with ADI parts. Here you can find a generic driver which can be used as a base for any microcontroller platform and also specific drivers for Renesas platforms.

HW Platform(s):

Driver Description

The driver contains two parts:

The driver for the ADXL345 part, which may be used, without modifications, with any microcontroller.
The Communication Driver, where the specific communication functions for the desired type of processor and communication protocol have to be implemented. This driver implements the communication with the device and hides the actual details of the communication protocol to the ADI driver.

The Communication Driver has a standard interface, so the ADXL345 driver can be used exactly as it is provided. There are three functions which are called by the ADXL345 driver:

I2C_Init() – initializes the communication peripheral.
I2C_Write() – writes data to the device.
I2C_Read() – reads data from the device.

Driver architecture

The implementation of these three functions depends on the used microcontroller.

The driver for ADXL345 contains functions for reading or writing any of the registers, for placing the device into standby or measure mode, for enable or disable various types of events detection, etc.

The following functions are implemented in this version of ADXL345 driver:

Function	Description
void ADXL345_SetRegisterValue(unsigned char registerAddress, unsigned char registerValue)	Writes data into a register.
unsigned char ADXL345_GetRegisterValue(unsigned char registerAddress)	Reads the value of a register.
unsigned char ADXL345_Init(void)	Initializes the I2C peripheral and checks if the ADXL345 part is present.
void ADXL345_SetPowerMode(unsigned char pwrMode)	Places the device into standby/measure mode.
void ADXL345_GetXyz(unsigned short* x, unsigned short* y, unsigned short* z)	Reads the output data of each axis.
void ADXL345_SetTapDetection(unsigned char tapType, unsigned char tapAxes, unsigned char tapDur, unsigned char tapLatent, unsigned char tapWindow, unsigned char tapThresh, unsigned char tapInt)	Enables/disables the tap detection.
void ADXL345_SetActivityDetection(unsigned char actOnOff, unsigned char actAxes, unsigned char actAcDc, unsigned char actThresh, unsigned char actInt)	Enables/disables the activity detection.
void ADXL345_SetInactivityDetection(unsigned char inactOnOff, unsigned char inactAxes, unsigned char inactAcDc, unsigned char inactThresh, unsigned char inactTime, unsigned char inactInt)	Enables/disables the inactivity detection.
void ADXL345_SetFreeFallDetection(unsigned char ffOnOff, unsigned char ffThresh, unsigned char ffTime, unsigned char ffInt)	Enables/disables the free-fall detection.
void ADXL345_SetOffset(unsigned char xOffset, unsigned char yOffset, unsigned char zOffset)	Calibrates the accelerometer.

Downloads

Renesas RX62N Quick Start Guide

This section contains a description of the steps required to run the ADXL345 demonstration project on a Renesas RX62N platform.

Required Hardware

Renesas Demo Kit for RX62N (Renesas)

Required Software

Hardware Setup

For this project it was used the ADXL345 part installed on the Renesas Demonstration Kit (RDK) for RX62N.

Software Project Setup

This section presents the steps for developing a software application that will run on the Renesas Demo Kit for RX62N for controlling and monitoring the operation of the ADI part.

Run the High-performance Embedded Workshop integrated development environment.
A window will appear asking to create or open project workspace. Choose “Create a new project workspace” option and press OK.
From “Project Types” option select “Application”, name the Workspace and the Project “ADIEvalBoard”, select the “RX” CPU family and “Renesas RX Standard” tool chain. Press OK.

A few windows will appear asking to configure the project:
- In the “Select Target CPU” window, select “RX600” CPU series, “RX62N” CPU Type and press Next.
- In the “Option Setting” windows keep default settings and press Next.
- In the “Setting the Content of Files to be generated” window select “None” for the “Generate main() Function” option and press Next.
- In the “Setting the Standard Library” window press “Disable all” and then Next.
- In the “Setting the Stack Area” window check the “Use User Stack” option and press Next.
- In the “Setting the Vector” window keep default settings and press Next.
- In the “Setting the Target System for Debugging” window choose “RX600 Segger J-Link” target and press Next.
- In the “Setting the Debugger Options” and “Changing the Files Name to be created” windows keep default settings, press Next and Finish.
The workspace is created.

The RPDL (Renesas Peripheral Driver Library) has to integrated in the project. Unzip the RPDL files (double-click on the file “RPDL_RX62N.exe”). Navigate to where the RPDL files were unpacked and double-click on the “Copy_RPDL_RX62N.bat” to start the copy process. Choose the LQFP package, type the full path where the project was created and after the files were copied, press any key to close the window.
The new source files have to be included in the project. Use the key sequence Alt, P, A to open the “Add files to project ‘ADIEvalBoard’” window. Double click on the RPDL folder. From the “Files of type” drop-down list, select “C source file (*.C)”. Select all of the files and press Add.

To avoid conflicts with standard project files remove the files “intprg.c” and “vecttbl.c” which are included in the project. Use the key sequence Alt, P, R to open the “Remove Project Files” window. Select the files, click on Remove and press OK.

Next the new directory has to be included in the project. Use the key sequence Alt, B, R to open the “RX Standard Toolchain” window. Select the C/C++ tab, select “Show entries for: Include file directories” and press Add. Select “Relative to: Project directory”, type “RPDL” as sub-directory and press OK.

The library file path has to be added in the project. Select the Link/Library tab, select “Show entries for: Library files” and press Add. Select “Relative to: Project directory”, type “RPDL\RX62N_library” as file path and press OK.

Because the “intprg.c” file was removed the “PIntPrg” specified in option “start” has to be removed. Change “Category” to “Section”. Press “Edit”, select “PIntPRG” and press “Remove”. From this window the address of each section can be also modified. After all the changes are made press OK two times.

At this point the files extracted from the zip file located in the “Software Tools” section have to be added into the project. Copy all the files from the archive into the project folder.

Now, the files have to be included in the project. Use the key sequence Alt, P, A to open the “Add files to project ‘ADIEvalBoard’” window. Navigate into ADI folder. From the “Files of type” drop-down list, select “Project Files”. Select all the copied files and press Add.

Now, the project is ready to be built. Press F7. The message after the Build Process is finished has to be “0 Errors, 0 Warnings”. To run the program on the board, you have to download the firmware into the microprocessor’s memory.

03 Feb 2012 15:32 · Dragos Bogdan