B4R Tutorial Visualizing ADXL345 3-axis Accelerometer Pitch and Roll with inline C and Processing

Johan Schoeman

Expert
Licensed User
The attached project is based on this posting:

Have downloaded and installed https://processing.org/


Steps:
1. Connect the ADXL345 to your Arduino device (I am using a Nana with I2C comms. The ADXL345's SDA pin goes to A4 and its SCL pin goes to A5 of the Nano
2. Download and install Processing
3. Unzip attached sketch_200215a.zip and copy it to wherever you want (I have it in my B4R sample project folder). The extracted file will be sketch_200215a.pde
4. Unzip attached B4R project
5. Run the B4R project (with your Nano/Uno/etc) connected
6. Disconnect the serial logging in the Logs tab of the B4R IDE
7. Double click on sketch_200215a.pde (after Processing has been installed)
8. Click the RUN button once the Processing IDE has opened with the sketch
9. Move the ADXL345 around and see the block moving.

Make sure you set the port correctly in the .pde sketch. My Nano shows as connected to com46

B4X:
  myPort = new Serial(this, "COM46", 115200); // starts the serial communication
B4R sample code:
B4X:
#Region Project Attributes
    #AutoFlushLogs: True
    #CheckArrayBounds: True
    #StackBufferSize: 300
#End Region

Sub Process_Globals
    'These global variables will be declared once when the application starts.
    'Public variables can be accessed from all modules.
    Public Serial1 As Serial
End Sub

Private Sub AppStart
    Serial1.Initialize(115200)
    Log("AppStart")
   
    RunNative("setup1", Null)
   
    AddLooper("mylooper")
   
End Sub

Sub myLooper
   
    RunNative("loop1", Null)
    Delay(50)
End Sub

#If C


/*
    Arduino and ADXL345 Accelerometer - 3D Visualization Example
     by Dejan, https://howtomechatronics.com
*/
#include <Wire.h>  // Wire library - used for I2C communication

int ADXL345 = 0x53; // The ADXL345 sensor I2C address

float X_out, Y_out, Z_out;  // Outputs
float roll,pitch,rollF,pitchF=0;

void setup1(B4R::Object* o) {
      Serial.begin(115200); // Initiate serial communication for printing the results on the Serial monitor
   
      Wire.begin(); // Initiate the Wire library
      // Set ADXL345 in measuring mode
      Wire.beginTransmission(ADXL345); // Start communicating with the device
      Wire.write(0x2D); // Access/ talk to POWER_CTL Register - 0x2D
      // Enable measurement
      Wire.write(8); // Bit D3 High for measuring enable (8dec -> 0000 1000 binary)
      Wire.endTransmission();
      delay(10);

      //Off-set Calibration
      //X-axis
      Wire.beginTransmission(ADXL345);
      Wire.write(0x1E);
      Wire.write(1);                  //value specifically for the ADXL345 that I am using
      Wire.endTransmission();
      delay(10);
     
      //Y-axis
      Wire.beginTransmission(ADXL345);
      Wire.write(0x1F);
      Wire.write(-2);                //value specifically for the ADXL345 that I am using
      Wire.endTransmission();
      delay(10);

      //Z-axis
      Wire.beginTransmission(ADXL345);
      Wire.write(0x20);
      Wire.write(-9);               //value specifically for the ADXL345 that I am using
      Wire.endTransmission();
      delay(10);
}

void loop1(B4R::Object* o) {
      // === Read acceleromter data === //
      Wire.beginTransmission(ADXL345);
      Wire.write(0x32); // Start with register 0x32 (ACCEL_XOUT_H)
      Wire.endTransmission(false);
      Wire.requestFrom(ADXL345, 6, true); // Read 6 registers total, each axis value is stored in 2 registers
      X_out = ( Wire.read() | Wire.read() << 8); // X-axis value
      X_out = X_out / 256; //For a range of +-2g, we need to divide the raw values by 256, according to the datasheet
      Y_out = ( Wire.read() | Wire.read() << 8); // Y-axis value
      Y_out = Y_out / 256;
      Z_out = ( Wire.read() | Wire.read() << 8); // Z-axis value
      Z_out = Z_out / 256;

      // Calculate Roll and Pitch (rotation around X-axis, rotation around Y-axis)
      roll = atan(Y_out / sqrt(pow(X_out, 2) + pow(Z_out, 2))) * 180 / PI;
      pitch = atan(-1 * X_out / sqrt(pow(Y_out, 2) + pow(Z_out, 2))) * 180 / PI;

      // Low-pass filter
      rollF = 0.94 * rollF + 0.06 * roll;
      pitchF = 0.94 * pitchF + 0.06 * pitch;

      Serial.print(rollF);
      Serial.print("/");
      Serial.println(pitchF);
}


#End If
Processing sample code:
B4X:
/*
    Arduino and ADXL345 Accelerometer - 3D Visualization Example
     by Dejan, https://howtomechatronics.com
*/

import processing.serial.*;
import java.awt.event.KeyEvent;
import java.io.IOException;

Serial myPort;

String data="";
float roll, pitch;

void setup() {
  size (960, 640, P3D);
  myPort = new Serial(this, "COM46", 115200); // starts the serial communication
  myPort.bufferUntil('\n');
}

void draw() {
  translate(width/2, height/2, 0);
  background(33);
  textSize(22);
  text("Roll: " + int(roll) + "     Pitch: " + int(pitch), -100, 265);

  // Rotate the object
  rotateX(radians(roll));
  rotateZ(radians(-pitch));

  // 3D 0bject
  textSize(30);
  fill(0, 76, 153);
  box (386, 40, 200); // Draw box
  textSize(25);
  fill(255, 255, 255);
  text("Connected to B4R", -183, 10, 101);
//  textAlign(CENTER);

  //delay(10);
  //println("ypr:\t" + angleX + "\t" + angleY); // Print the values to check whether we are getting proper values
}

// Read data from the Serial Port
void serialEvent (Serial myPort) {
  // reads the data from the Serial Port up to the character '.' and puts it into the String variable "data".
  data = myPort.readStringUntil('\n');

  // if you got any bytes other than the linefeed:
  if (data != null) {
    data = trim(data);
    // split the string at "/"
    String items[] = split(data, '/');
    if (items.length > 1) {

      //--- Roll,Pitch in degrees
      roll = float(items[0]);
      pitch = float(items[1]);
    }
  }
}
 

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