Sunday, October 2, 2016

Three Axis Accelerometer ADXL345

by JBWylzan


Project 27:  Accelerometer ADXL345

This project shows how to test a 3-axis accelerometer
through the Serial Monitor and control a video camera.


ADXL 345 Accelerometer from JB Wylzan on Vimeo.


Hardware:
1 accelerometer; ADXL345
1 prototype shield
3 servos (optional)
connecting wires scl5 sda4 cs2
Arduino R3 UNO board

Block Diagram:





Serial Monitor Test:
/* ===============================================================
      Project # 27: Accelerometer ADXL345 Testing
      Author: J. B. Wylzan with the Arduino Community
      Website: http://www.ihackrobot.blogspot.com
      Abstract: How to test a 3-axis accelerometer
================================================================== */

#include <Wire.h>

#define ADXL345_ADDRESS (0xA6 >> 1)
#define ADXL345_REGISTER_XLSB (0x32)
int accelerometer_data[3];
                                 
void i2c_write(int address, byte reg, byte data) {                                                                    
Wire.beginTransmission(address);      
Wire.write(reg);                              
Wire.write(data);                              
Wire.endTransmission();
}
                                             
void i2c_read(int address, byte reg, int count, byte* data) {
int i = 0;                                                
Wire.beginTransmission(address);        
Wire.write(reg);                                  
Wire.endTransmission();
Wire.beginTransmission(address);
Wire.requestFrom(address, count);
while(Wire.available())                  
{
char c = Wire.read();                    
data[i] = c;
i++;
}
Wire.endTransmission();
}

void init_adxl345() {
byte data = 0;
i2c_write(ADXL345_ADDRESS, 0x31, 0x0B);             // 13-bit mode +_ 16g
i2c_write(ADXL345_ADDRESS, 0x2D, 0x08);             // Power register
i2c_write(ADXL345_ADDRESS, 0x1E, 0x00);             // X
i2c_write(ADXL345_ADDRESS, 0x1F, 0x00);             // Y
i2c_write(ADXL345_ADDRESS, 0x20, 0x05);              // Z

// View values on the serial monitor!
i2c_read(ADXL345_ADDRESS, 0X00, 1, &data);
if(data==0xE5)
Serial.println("Success");
else
Serial.println("Failure");
}

void read_adxl345() {
byte bytes[6];
memset(bytes,0,6);
i2c_read(ADXL345_ADDRESS, ADXL345_REGISTER_XLSB, 6, bytes);
for (int i=0;i<3;++i) {
accelerometer_data[i] = (int)bytes[2*i] + (((int)bytes[2*i + 1]) << 8);
}
}

void setup() {
Wire.begin();
Serial.begin(9600);
for(int i=0; i<3; ++i) {
accelerometer_data[i] = 0;
}
init_adxl345();
}

void loop() {
read_adxl345();
Serial.print("x-y-z: ");
Serial.print(float(accelerometer_data[0])*3.9/1000);    
Serial.print("\t");
Serial.print(float(accelerometer_data[1])*3.9/1000);
Serial.print("\t");
Serial.print(float(accelerometer_data[2])*3.9/1000);
Serial.print("\n");
delay(100);
}




Code # 27:
/* scl = a5   sda = a4  */

#include <Wire.h>
#include <Servo.h>
Servo servox;
#define device (0xA6 >> 1)   //(0x53)    
int ledpin = 11;
byte mem[6] ;
int i;
int x;

void setup(){
 pinMode(ledpin,OUTPUT);
 digitalWrite(ledpin,HIGH);
 Wire.begin();
 servox.attach(9);
 servox.write(90);
 delay(25);
writeTo(device, 0x2D, 8);
}

void loop(){
 int regAddress = 0x32;
 digitalWrite(ledpin,LOW);
 delay(10);
 digitalWrite(ledpin,HIGH);
 readFrom(device, regAddress, 6, mem);

 x=0;
 for(i=1;i<=5;i++){
 x += (((int)mem[1]) << 8) | mem[0];
 delay(10);
 }

 x/=5;
 if(x<-255)x= -255; else if (x>255)x=255;
 x=map(x, -255, 255, 0, 180);
 servox.write(x);
 delay(200);
}

void writeTo(int DEVICE, byte address, byte val) {
 Wire.beginTransmission(DEVICE);
 Wire.write(address);
 Wire.write(val);
 Wire.endTransmission();
}

void readFrom(int DEVICE, byte address, int num, byte mem[]) {
 Wire.beginTransmission(DEVICE);
 Wire.write(address);
 Wire.endTransmission();
 Wire.beginTransmission(DEVICE);
 Wire.requestFrom(DEVICE, num);

 int i = 0;
 while(Wire.available())  {
 mem[i]= Wire.read();
 i++;
 }
 Wire.endTransmission();
}


Challenge:
1. Try to control 2 servos, 
2. Try to control 3 servos.
3. Add a Laser beam or a turret
4. Try the Alert Detection below 


/*
Example      Sabotage Detection
Author        Stefan Hermann
Date         5.12.2011
*/

int myState=0;
int greenLedPin=11;
int redLedPin=7;
int blueLedPin=3;
int buttonPin=2;
int potPin=3;
int accZPin=0;
int accYPin=1;
int accXPin=2;

int startAccZ;
int startAccY;
int startAccX;

void setup(){
  pinMode(greenLedPin,OUTPUT);
  pinMode(redLedPin,OUTPUT);
  pinMode(blueLedPin,OUTPUT);
  pinMode(buttonPin,INPUT);
  startAccZ=analogRead(accZPin);
  startAccY=analogRead(accYPin);
  startAccX=analogRead(accXPin);
}

void alertBlinking(){
  digitalWrite(redLedPin,HIGH);
  delay(50);
  digitalWrite(redLedPin,LOW);
  delay(100);
  digitalWrite(blueLedPin,HIGH);
  delay(50);
  digitalWrite(blueLedPin,LOW); 
  delay(100);  
}

boolean senseAcceleration(int myPotVal){
  boolean myReturn=false;
  myPotVal=map(myPotVal,0,1023,0,10);
  if (analogRead(accXPin)>startAccX+myPotVal) myReturn=true;
  if (analogRead(accYPin)>startAccY+myPotVal) myReturn=true;
  if (analogRead(accZPin)>startAccZ+myPotVal) myReturn=true;
  return myReturn;
}

void loop(){
  //alertBlinking();
  switch (myState){
  case 0: //idle
    if (senseAcceleration(analogRead(potPin))==true) {
      digitalWrite(greenLedPin,LOW);
      myState=1;
    } else {
      digitalWrite(greenLedPin,HIGH);    
    };
    break;
  case 1: // alert
    alertBlinking();
    if (digitalRead(buttonPin)==HIGH){
      myState=0;
    }
    break;
  }
  delay(10);
}



Disclaimer:  We shall not be liable for any loss or damage of whatever nature - direct, indirect, consequential, or otherwise - which may arise as a result of your use of any information on this website. However, if you are interested in using any of the projects for personal or educational purposes, please inform the author by email. 

Public Domain Notice: Copyright (c) 2000. All rights reserved. This article is part of a book entitled iHackRobot. Copies are welcome to be shared or distributed publicly as long proper citations are observed. Please cite as follows: A Journal of a Creative Mind, Joey Lawsin, 1988, USA.


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The Homotronics® and Homodruinos® logos are registered trademarks.
Copyright Biotronics© Inc. iHackRobot®. All Rights Reserved.
Patent Pending. 2000 © ®


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