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Topic: Visualizing Accelerometer data in Processing (Read 1 time) previous topic - next topic


Hello All,

I am using the following code to access accelerometer data from Arduino and need to plot a real time graph on Processing.

Arduino Code:

#include "NAxisMotion.h"        //Contains the bridge code between the API and the Arduino Environment
#include <Wire.h>

NAxisMotion mySensor;                 //Object that for the sensor
unsigned long lastStreamTime = 0;     //To store the last streamed time stamp
const int streamPeriod = 40;          //To stream at 25Hz without using additional timers (time period(ms) =1000/frequency(Hz))
bool updateSensorData = true;         //Flag to update the sensor data. Default is true to perform the first read before the first stream

void setup() //This code is executed once
  //Peripheral Initialization
  Serial.begin(115200);           //Initialize the Serial Port to view information on the Serial Monitor
  I2C.begin();                    //Initialize I2C communication to the let the library communicate with the sensor.
  //Sensor Initialization
  mySensor.initSensor();          //The I2C Address can be changed here inside this function in the library
  mySensor.setOperationMode(OPERATION_MODE_NDOF);   //Can be configured to other operation modes as desired
  mySensor.setUpdateMode(MANUAL);  //The default is AUTO. Changing to manual requires calling the relevant update functions prior to calling the read functions
  //Setting to MANUAL requires lesser reads to the sensor
  updateSensorData = true;
  Serial.println("Default accelerometer configuration settings...");
  Serial.print("Range: ");
  Serial.print("Bandwidth: ");
  Serial.print("Power Mode: ");
  Serial.println("Streaming in ..."); //Countdown
  delay(1000);  //Wait for a second
  delay(1000);  //Wait for a second
  delay(1000);  //Wait for a second

void loop() //This code is looped forever
  if (updateSensorData)  //Keep the updating of data as a separate task
    mySensor.updateAccel();        //Update the Accelerometer data
    mySensor.updateLinearAccel();  //Update the Linear Acceleration data
    mySensor.updateGravAccel();    //Update the Gravity Acceleration data
    mySensor.updateCalibStatus();  //Update the Calibration Status
    updateSensorData = false;
  if ((millis() - lastStreamTime) >= streamPeriod)
    lastStreamTime = millis();

    //Serial.print("Time: ");
    //Serial.print("ms ");

    //Serial.print("      aX: ");
    Serial.print(mySensor.readAccelX()); //Accelerometer X-Axis data
    //Serial.print("m/s2 ");


    updateSensorData = true;

The processing code, which I try to modify is following:

import processing.serial.*;

Serial myPort; // The serial port
int xPos = 1; // horizontal position of the graph

void setup () {
// set the window size:
size(400, 300);

// List all the available serial ports

// I know that the first port in the serial list on my mac
// is always my Arduino, so I open Serial.list()[0].
// Open whatever port is the one you're using.
myPort = new Serial(this, Serial.list()[0], 115200);
// don't generate a serialEvent() unless you get a newline character:
// set inital background:
void draw () {
// everything happens in the serialEvent()

void serialEvent (Serial myPort) {
// get the ASCII string:
String inString = myPort.readStringUntil('\n');

if (inString != null) {
// trim off any whitespace:
inString = trim(inString);
// convert to an int and map to the screen height:
float inByte = float(inString);
inByte = map(inByte, 0, 1023, 0, height);
// draw the line:
line(xPos, height, xPos, height - inByte);

// at the edge of the screen, go back to the beginning:
if (xPos >= width) {
xPos = 0;
else {
// increment the horizontal position:

What I want to try as a first step is just send one stream of value for instance "aX" and plot it with respect to time in real time. Even though I see the values in Arduino, I stream something else in Processing, and above all the Graphic window is absolutely blank.
Can anyone tell me, where the problem lies?


Even though I see the values in Arduino, I stream something else in Processin
You can't see the values in Arduino. You might me able to see the values in the Serial Monitor application that connects to the serial port that the Arduino is sending data to.

But, if you are doing that, then Processing can't connect to the same serial port, so it is not surprising that it can't get any data.

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