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Topic: Arduino UNO and ADXL 345 Accelerometer (Read 34410 times) previous topic - next topic


Nov 17, 2012, 05:56 pm Last Edit: Nov 17, 2012, 06:05 pm by sergioclick Reason: 1
Hello to community,

I was bought this accelerometer in DX.com


But I don't know how connect it correctly with Ardino UNO board...

This is a shot of my protoboard with all elements:

Red cables are 3.3v
Blue cable are ground
Yellow cables are A4 and A5 connections

I got this design from http://bildr.org/2011/03/adxl345-arduino/  and http://arduino.cc/forum/index.php?topic=97486.0 (the connections are from latest web)

And.. this is my code...

Code: [Select]
void setup()
 pinMode(A4, INPUT);
 pinMode(A5, INPUT);

void loop()


(Evidently, this code is very simple but i think is correct)

Every second, I receive the same numbers from A4 and A5 pin (although I move the accelerometer)

What is wrong?

Thanks in advance for you help (I'm very very begginer)


I don't know how connect it correctly with Ardino UNO board...

Reading the adxl345 datasheet would help you greatly.


Dec 09, 2012, 08:48 pm Last Edit: Dec 09, 2012, 08:50 pm by he3r0 Reason: 1
hello,a few days back i've had the same problem,
though i have arduino mega 2560,
there are two things that I would change.
solder pins to the accelerometer,

and in your code,
before void setup()
seems that I'm missing
library declaration for ADXL345

and this is how it is looking on my setup (i've dumped serial for LCD)


and this is how my code looks like (pin setting is for mega, with SDA, SCL @ 21 and 22)

Code: [Select]

#include <Wire.h>
// include the library code for ADXL345:
#include <ADXL345.h>
// include the library code for LCD:
#include <LiquidCrystal.h>

// initialize the LCD library with the numbers of the interface pins
LiquidCrystal lcd(7, 6, 5, 4, 3, 2);

ADXL345 adxl; //variable adxl is an instance of the ADXL345 library

void setup(){
 // set up the LCD's number of columns and rows:
 lcd.begin(20, 4);
 // Print a message to the LCD.
 lcd.print("Czas od resetu:");

//code from old sample code attached to the library.
 //set activity/ inactivity thresholds (0-255)
 adxl.setActivityThreshold(75); //62.5mg per increment
 adxl.setInactivityThreshold(75); //62.5mg per increment
 adxl.setTimeInactivity(10); // how many seconds of no activity is inactive?

 //look of activity movement on this axes - 1 == on; 0 == off

 //look of inactivity movement on this axes - 1 == on; 0 == off

 //look of tap movement on this axes - 1 == on; 0 == off

 //set values for what is a tap, and what is a double tap (0-255)
 adxl.setTapThreshold(50); //62.5mg per increment
 adxl.setTapDuration(15); //625?s per increment
 adxl.setDoubleTapLatency(80); //1.25ms per increment
 adxl.setDoubleTapWindow(200); //1.25ms per increment

 //set values for what is considered freefall (0-255)
 adxl.setFreeFallThreshold(7); //(5 - 9) recommended - 62.5mg per increment
 adxl.setFreeFallDuration(45); //(20 - 70) recommended - 5ms per increment

 //setting all interupts to take place on int pin 1
 //I had issues with int pin 2, was unable to reset it
 adxl.setInterruptMapping( ADXL345_INT_SINGLE_TAP_BIT,   ADXL345_INT1_PIN );
 adxl.setInterruptMapping( ADXL345_INT_DOUBLE_TAP_BIT,   ADXL345_INT1_PIN );
 adxl.setInterruptMapping( ADXL345_INT_FREE_FALL_BIT,    ADXL345_INT1_PIN );
 adxl.setInterruptMapping( ADXL345_INT_ACTIVITY_BIT,     ADXL345_INT1_PIN );
 adxl.setInterruptMapping( ADXL345_INT_INACTIVITY_BIT,   ADXL345_INT1_PIN );

 //register interupt actions - 1 == on; 0 == off  
 adxl.setInterrupt( ADXL345_INT_SINGLE_TAP_BIT, 1);
 adxl.setInterrupt( ADXL345_INT_DOUBLE_TAP_BIT, 1);
 adxl.setInterrupt( ADXL345_INT_FREE_FALL_BIT,  1);
 adxl.setInterrupt( ADXL345_INT_ACTIVITY_BIT,   1);
 adxl.setInterrupt( ADXL345_INT_INACTIVITY_BIT, 1);

void loop(){
 //Boring accelerometer stuff  
 int x,y,z;  
 adxl.readAccel(&x, &y, &z); //read the accelerometer values and store them in variables  x,y,z

 // set the cursor to column 0, line 1
 // (note: line 1 is the second row, since counting begins with 0):
 lcd.setCursor(0, 1);
 // print the number of seconds since reset:
 lcd.print(" sek");
 lcd.setCursor(0, 2);
 //prints X, Y, Z values on to LCD
 lcd.print(" ");
 lcd.print(" ");  
 lcd.print(" ");  


and the one website with great writeup I've used to get my thing to run.


And... don't forget to solder the header pins to the break out board if you want to get meaningful readings.


Hi, i am new to arduino and adxl345
  i want some checks when accelorometer is move in any coordinates if it is idol don't do any thing but if show some movement some info should be send to serial monitor .
i am using the same library

please help
thanks in advance

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