Parsing values from Arduino to processing.

in Integration and Hardware • 8 months ago

I'm trying to parse my values which i get from my 6 DOF inertial measurement unit , from arduino to processing. So far, following results have been accomplished.

1. Sent the float values as string to processing. Converted them back to float in processing and displayed.

Problem : When i tilt my IMU, the values changes accordingly, but these changes are not affected in processing, but it is successfully affected in arduino serial monitor. There is only slight variation in processing, say from 5.8 to 6.2 when i do a 90 degree tilt, whereas the actual should have been like about 5.8 to 70.4 or something.

This is the code fragment from arduino.

mpu.dmpGetQuaternion(&q, fifoBuffer);
mpu.dmpGetEuler(euler, &q);
Serial.println(euler[0] * 180/M_PI);
Serial.println(euler[1] * 180/M_PI);
Serial.println(euler[2] * 180/M_PI);

And this is my Processing sketch.

import processing.serial.*;
import processing.opengl.*;
Serial myPort;
float[] value=new float[4];
int i=0;
int k=100;
String[] msg=new String[5];
void setup()
{
size(600,600,OPENGL);
noStroke();
String portName="COM4";
myPort = new Serial(this, portName, 115200);
frameRate(50);
background(255);
fill(246, 225, 65);
lights();
}
void draw()
{
if(i>2)
i=0;
msg[i] = myPort.readStringUntil(13);
if(msg[i] != null)
{
value[i] = float(msg[i]);
println(value);
}
++i;
background(255);
translate(width/2,0);
fill(0);
text("Yaw: " + ((float) value[0]), 0, k);
text("Pitch: " + ((float) value[1]), 100, k);
text("Roll: " + ((float) value[2]), 200, k);
}

Replies(7)

benja

Re: Parsing values from Arduino to processing.

8 months ago

Hey,

the whole arduino-code would be interesting. do you have delays between sending messages? Arduinos usually run faster than the processing sketches framRate.
At the moment you read one line from the serial-buffer in every draw-loop, but you send three lines from arduino.
I would recommend to send only one string with all values from arduino, otherwise they could get mixed up.
Then try to use serialEvent(), it's more reliable than reading the messages in draw().

grimreape..

Re: Parsing values from Arduino to processing.

8 months ago

Thanks for your reply. Actually i did try giving a delay of 10ms, but didn't work out well. Here's the rest of the arduino code.

#include "Wire.h"
#include "I2Cdev.h"
#include "MPU6050_6Axis_MotionApps20.h"
#define LED_PIN 13
bool blinkState = false;
// MPU control/status vars
bool dmpReady = false; // set true if DMP init was successful
uint8_t mpuIntStatus; // holds actual interrupt status byte from MPU
uint8_t devStatus; // return status after each device operation (0 = success, !0 = error)
uint16_t packetSize; // expected DMP packet size (default is 42 bytes)
uint16_t fifoCount; // count of all bytes currently in FIFO
uint8_t fifoBuffer[64]; // FIFO storage buffer
// orientation/motion vars
Quaternion q; // [w, x, y, z] quaternion container
VectorInt16 aa; // [x, y, z] accel sensor measurements
VectorInt16 aaReal; // [x, y, z] gravity-free accel sensor measurements
VectorInt16 aaWorld; // [x, y, z] world-frame accel sensor measurements
VectorFloat gravity; // [x, y, z] gravity vector
float euler[3]; // [psi, theta, phi] Euler angle container
float ypr[3]; // [yaw, pitch, roll] yaw/pitch/roll container and gravity vector
// packet structure for InvenSense teapot demo
uint8_t teapotPacket[14] = { '$', 0x02, 0,0, 0,0, 0,0, 0,0, 0x00, 0x00, '\r', '\n' };
// ================================================================
// === INTERRUPT DETECTION ROUTINE ===
// ================================================================
volatile bool mpuInterrupt = false; // indicates whether MPU interrupt pin has gone high
void dmpDataReady() {
mpuInterrupt = true;
}
// ================================================================
// === INITIAL SETUP ===
// ================================================================
void setup() {
Wire.begin();
Serial.begin(115200);
while (!Serial); // wait for Leonardo enumeration, others continue immediately
// initialize device
Serial.println(F("Initializing I2C devices..."));
mpu.initialize();
// verify connection
Serial.println(F("Testing device connections..."));
Serial.println(mpu.testConnection() ? F("MPU6050 connection successful") : F("MPU6050 connection failed"));
while (Serial.available() && Serial.read()); // empty buffer
// load and configure the DMP
Serial.println(F("Initializing DMP..."));
devStatus = mpu.dmpInitialize();
// make sure it worked (returns 0 if so)
if (devStatus == 0) {
// turn on the DMP, now that it's ready
Serial.println(F("Enabling DMP..."));
mpu.setDMPEnabled(true);
// enable Arduino interrupt detection
Serial.println(F("Enabling interrupt detection (Arduino external interrupt 0)..."));
attachInterrupt(0, dmpDataReady, RISING);
mpuIntStatus = mpu.getIntStatus();
// set our DMP Ready flag so the main loop() function knows it's okay to use it
Serial.println(F("DMP ready! Waiting for first interrupt..."));
dmpReady = true;
// get expected DMP packet size for later comparison
packetSize = mpu.dmpGetFIFOPacketSize();
} else {
// ERROR!
// 1 = initial memory load failed
// 2 = DMP configuration updates failed
// (if it's going to break, usually the code will be 1)
Serial.print(F("DMP Initialization failed (code "));
Serial.print(devStatus);
Serial.println(F(")"));
}
// configure LED for output
pinMode(LED_PIN, OUTPUT);
}
// ================================================================
// === MAIN PROGRAM LOOP ===
// ================================================================
void loop() {
// if programming failed, don't try to do anything
if (!dmpReady) return;
// wait for MPU interrupt or extra packet(s) available
while (!mpuInterrupt && fifoCount < packetSize) {
// other program behavior stuff here
// .
// .
// .
// if you are really paranoid you can frequently test in between other
// stuff to see if mpuInterrupt is true, and if so, "break;" from the
// while() loop to immediately process the MPU data
// .
// .
// .
}
// reset interrupt flag and get INT_STATUS byte
mpuInterrupt = false;
mpuIntStatus = mpu.getIntStatus();
// get current FIFO count
fifoCount = mpu.getFIFOCount();
// check for overflow (this should never happen unless our code is too inefficient)
if ((mpuIntStatus & 0x10) || fifoCount == 1024) {
// reset so we can continue cleanly
mpu.resetFIFO();
Serial.println(F("FIFO overflow!"));
// otherwise, check for DMP data ready interrupt (this should happen frequently)
} else if (mpuIntStatus & 0x02) {
// wait for correct available data length, should be a VERY short wait
while (fifoCount < packetSize) fifoCount = mpu.getFIFOCount();
// read a packet from FIFO
mpu.getFIFOBytes(fifoBuffer, packetSize);
// track FIFO count here in case there is > 1 packet available
// (this lets us immediately read more without waiting for an interrupt)
fifoCount -= packetSize;
// display Euler angles in degrees
mpu.dmpGetQuaternion(&q, fifoBuffer);
mpu.dmpGetEuler(euler, &q);
Serial.println(euler[0] * 180/M_PI);
Serial.println(euler[1] * 180/M_PI);
Serial.println(euler[2] * 180/M_PI);
}

benja

Re: Parsing values from Arduino to processing.

8 months ago

The problem could be, that when the arduino loop() only takes for example 5 ms to execute (i think i can't test it without your hardware), it runs 200 times per second, sending 3*200 messages via serial.
Your processing-sketch runs on 50 frames per second parsing 1 message on every frame, so it takes 6 seconds to parse the messages that you send in the first second. This should result in a huge delay after several seconds.

Because of this, you should use serialEvent(), wich is called every time a serial message is recieved.

Still is see a problem in differentiating the different values, this is why i recommend to send them in one message, like this for example:

Serial.print(euler[0] * 180/M_PI);
Serial.print(" ");
Serial.print(euler[1] * 180/M_PI);
Serial.print(" ");
Serial.println(euler[2] * 180/M_PI);

grimreape..

Re: Parsing values from Arduino to processing.

8 months ago

I changed the arduino code like you've posted above. And this is the processing sketch with serialEvent. They aren't showing the values,value[0],value[1],value[2] show 0.0. I have a feeling the serialEvent function is not getting invoked. Heres the code.

import processing.serial.*;
Serial port;
float[] value=new float[4];
int i=0;
String mg;
void setup()
{
size(600,600);
port=new Serial(this, "COM4",115200);
frameRate(300);
background(255);
fill(246,225,65);
}
void draw()
{
background(255);
translate(width/2,0);
fill(0);
text("Yaw: " + ((float) value[0]), 0, 100);
text("Pitch: " + ((float) value[1]), 100, 100);
text("Roll: " + ((float) value[2]), 200, 100);
}
void SerialEvent(Serial port)
{
mg=port.readStringUntil(13);
fill(0);
if(mg!= null)
{
float value[] = float(split(mg, ' '));
println(value);
}
}

benja

Re: Parsing values from Arduino to processing.

8 months ago

I think you misspelled the function-name, try "serialEvent" with a small "s".

grimreape..

Re: Parsing values from Arduino to processing.

8 months ago

Thanks benja. It worked out fine. Also, i redeclared the array float in my serialEvent function. Now it works fine. I'll post a video of what i was working on, soon. :)

grimreape..

Re: Parsing values from Arduino to processing.

6 months ago

http://www.youtube.com/watch?v=4-0bxu5uKwY This is the simulator i was working on. :)

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