This page is to Setup and Config ADXL345

Hardware and Software

ADXL345, Arduino or Digispark / ESP8266

    Arduino IDE

Sanki Notes

  • I2C : 
  • SDA : A4  (Digispark D0)
  • SCL : A5  (Digispark D2)
  • SDO : GND
  • CS : V++
  • Example :


          This example is ..........
  1. #include <Wire.h>
    #define DEVICE (0x53)      //ADXL345 device address
    #define TO_READ (6)        //num of bytes we are going to read each time (two bytes for each axis)
    byte buff[TO_READ] ;        //6 bytes buffer for saving data read from the device
    char str[512];              //string buffer to transform data before sending it to the serial port
    int regAddress = 0x32;      //first axis-acceleration-data register on the ADXL345
    int x, y, z;                        //three axis acceleration data
    double roll = 0.00, pitch = 0.00;       //Roll & Pitch are the angles which rotate by the axis X and y 
    //in the sequence of R(x-y-z),more info visit
    void setup() {
      Wire.begin();         // join i2c bus (address optional for master)
      Serial.begin(9600);  // start serial for output
      //Turning on the ADXL345
      writeTo(DEVICE, 0x2D, 0);      
      writeTo(DEVICE, 0x2D, 16);
      writeTo(DEVICE, 0x2D, 8);
    void loop() {
      readFrom(DEVICE, regAddress, TO_READ, buff); //read the acceleration data from the ADXL345
                                                  //each axis reading comes in 10 bit resolution, ie 2 bytes.  Least Significat Byte first!!
                                                  //thus we are converting both bytes in to one int
      x = (((int)buff[1]) << 8) | buff[0];   
      y = (((int)buff[3])<< 8) | buff[2];
      z = (((int)buff[5]) << 8) | buff[4];
      //we send the x y z values as a string to the serial port
      Serial.print("The acceleration info of x, y, z are:");
      sprintf(str, "%d %d %d", x, y, z);  
      //Roll & Pitch calculate
      Serial.print("Roll:"); Serial.println( roll ); 
      Serial.print("Pitch:"); Serial.println( pitch );
      //It appears that delay is needed in order not to clog the port
    //---------------- Functions
    //Writes val to address register on device
    void writeTo(int device, byte address, byte val) {
      Wire.beginTransmission(device); //start transmission to device 
      Wire.write(address);        // send register address
      Wire.write(val);        // send value to write
      Wire.endTransmission(); //end transmission
    //reads num bytes starting from address register on device in to buff array
    void readFrom(int device, byte address, int num, byte buff[]) {
      Wire.beginTransmission(device); //start transmission to device 
      Wire.write(address);        //sends address to read from
      Wire.endTransmission(); //end transmission
        Wire.beginTransmission(device); //start transmission to device
      Wire.requestFrom(device, num);    // request 6 bytes from device
      int i = 0;
      while(Wire.available())    //device may send less than requested (abnormal)
        buff[i] =; // receive a byte
      Wire.endTransmission(); //end transmission
    //calculate the Roll&Pitch
    void RP_calculate(){
      double x_Buff = float(x);
      double y_Buff = float(y);
      double z_Buff = float(z);
      roll = atan2(y_Buff , z_Buff) * 57.3;
      pitch = atan2((- x_Buff) , sqrt(y_Buff * y_Buff + z_Buff * z_Buff)) * 57.3;
Sanki Poon,
2016年5月23日 下午8:32
Sanki Poon,
2016年5月24日 下午8:42