I am interfacing MPU6050 with Arduino using Simulink S-function builder. I'm implementing MPU6050_DMP6 code in Simulink s-function builder by following this video. By following this tutorial I implemented the S-function as: I set sample time 0.05 in s-function builder block and number of discrete state=1 and sample mode = 1. in the libraries tab I put the following code:
#include <math.h>
#ifndef MATLAB_MEX_FILE
int counter=0;
#include <Arduino.h>
#include "I2Cdev.h"
#include "I2Cdev.cpp"
#include "helper_3dmath.h"
#include "MPU6050_6Axis_MotionApps20.h"
#include "MPU6050.h" // not necessary if using MotionApps include file
#include "MPU6050.cpp" // not necessary if using MotionApps include file
// Arduino Wire library is required if I2Cdev I2CDEV_ARDUINO_WIRE implementation
// is used in I2Cdev.h
#if I2CDEV_IMPLEMENTATION == I2CDEV_ARDUINO_WIRE
#include "Wire.h"
#include "Wire.cpp"
#include "utility/twi.h"
#include "utility/twi.c"
#endif
// class default I2C address is 0x68
// specific I2C addresses may be passed as a parameter here
// AD0 low = 0x68 (default for SparkFun breakout and InvenSense evaluation board)
// AD0 high = 0x69
MPU6050 mpu;
#define OUTPUT_READABLE_YAWPITCHROLL
// uncomment "OUTPUT_READABLE_REALACCEL" if you want to see acceleration
// components with gravity removed. This acceleration reference frame is
// not compensated for orientation, so +X is always +X according to the
// sensor, just without the effects of gravity. If you want acceleration
// compensated for orientation, us OUTPUT_READABLE_WORLDACCEL instead.
//#define OUTPUT_READABLE_REALACCEL
// uncomment "OUTPUT_READABLE_WORLDACCEL" if you want to see acceleration
// components with gravity removed and adjusted for the world frame of
// reference (yaw is relative to initial orientation, since no magnetometer
// is present in this case). Could be quite handy in some cases.
//#define OUTPUT_READABLE_WORLDACCEL
// uncomment "OUTPUT_TEAPOT" if you want output that matches the
// format used for the InvenSense teapot demo
//#define OUTPUT_TEAPOT
#define INTERRUPT_PIN 2 // use pin 2 on Arduino Uno & most boards
#define LED_PIN 13 // (Arduino is 13, Teensy is 11, Teensy++ is 6)
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;
}
#endif
in the discrete update tab I have implemented following code:
if (xD[0]!=1){
#ifndef MATLAB_MEX_FILE
// join I2C bus (I2Cdev library doesn't do this automatically)
#if I2CDEV_IMPLEMENTATION == I2CDEV_ARDUINO_WIRE
Wire.begin();
Wire.setClock(400000); // 400kHz I2C clock. Comment this line if having compilation difficulties
#elif I2CDEV_IMPLEMENTATION == I2CDEV_BUILTIN_FASTWIRE
Fastwire::setup(400, true);
#endif
// initialize serial communication
// (115200 chosen because it is required for Teapot Demo output, but it's
// really up to you depending on your project)
Serial2.begin(115200);
// while (!Serial); // wait for Leonardo enumeration, others continue immediately
// NOTE: 8MHz or slower host processors, like the Teensy @ 3.3v or Ardunio
// Pro Mini running at 3.3v, cannot handle this baud rate reliably due to
// the baud timing being too misaligned with processor ticks. You must use
// 38400 or slower in these cases, or use some kind of external separate
// crystal solution for the UART timer.
// initialize device
Serial2.println(F("Initializing I2C devices..."));
mpu.initialize();
pinMode(INTERRUPT_PIN, INPUT);
// verify connection
Serial2.println(F("Testing device connections..."));
Serial2.println(mpu.testConnection() ? F("MPU6050 connection successful") : F("MPU6050 connection failed"));
// wait for ready
// Serial2.println(F("\nSend any character to begin DMP programming and demo: "));
// while (Serial2.available() && Serial2.read()); // empty buffer
// while (!Serial2.available()); // wait for data
// while (Serial2.available() && Serial2.read()); // empty buffer again
// load and configure the DMP
Serial2.println(F("Initializing DMP..."));
devStatus = mpu.dmpInitialize();
// supply your own gyro offsets here, scaled for min sensitivity
mpu.setXGyroOffset(220);
mpu.setYGyroOffset(76);
mpu.setZGyroOffset(-85);
mpu.setZAccelOffset(1788); // 1688 factory default for my test chip
// make sure it worked (returns 0 if so)
if (devStatus == 0) {
// turn on the DMP, now that it's ready
Serial2.println(F("Enabling DMP..."));
mpu.setDMPEnabled(true);
// enable Arduino interrupt detection
Serial2.println(F("Enabling interrupt detection (Arduino external interrupt 0)..."));
attachInterrupt(digitalPinToInterrupt(INTERRUPT_PIN), dmpDataReady, RISING);
mpuIntStatus = mpu.getIntStatus();
// set our DMP Ready flag so the main loop() function knows it's okay to use it
Serial2.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)
Serial2.print(F("DMP Initialization failed (code "));
Serial2.print(devStatus);
Serial2.println(F(")"));
}
#endif
xD[0]=1;
}
and in output tab I have implemented this code:
if (xD[0]==1){
#ifndef MATLAB_MEX_FILE
// 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();
// 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;
#ifdef OUTPUT_READABLE_QUATERNION
// display quaternion values in easy matrix form: w x y z
mpu.dmpGetQuaternion(&q, fifoBuffer);
// Serial.print("quat\t");
// Serial.print(q.w);
// Serial.print("\t");
// Serial.print(q.x);
// Serial.print("\t");
// Serial.print(q.y);
// Serial.print("\t");
// Serial.println(q.z);
#endif
#ifdef OUTPUT_READABLE_EULER
// display Euler angles in degrees
// mpu.dmpGetQuaternion(&q, fifoBuffer);
// mpu.dmpGetEuler(euler, &q);
// Serial.print("euler\t");
// Serial.print(euler[0] * 180/M_PI);
// Serial.print("\t");
// Serial.print(euler[1] * 180/M_PI);
// Serial.print("\t");
// Serial.println(euler[2] * 180/M_PI);
#endif
#ifdef OUTPUT_READABLE_YAWPITCHROLL
// display Euler angles in degrees
mpu.dmpGetQuaternion(&q, fifoBuffer);
mpu.dmpGetGravity(&gravity, &q);
mpu.dmpGetYawPitchRoll(ypr, &q, &gravity);
*roll = ypr[0] * 180/M_PI;
*pitch = ypr[1] * 180/M_PI;
*yaw = ypr[2] * 180/M_PI;
Serial2.print("ypr\t");
Serial2.print(ypr[0] * 180/M_PI);
Serial2.print("\t");
Serial2.print(ypr[1] * 180/M_PI);
Serial2.print("\t");
Serial2.println(ypr[2] * 180/M_PI);
#endif
#ifdef OUTPUT_READABLE_REALACCEL
// display real acceleration, adjusted to remove gravity
mpu.dmpGetQuaternion(&q, fifoBuffer);
mpu.dmpGetAccel(&aa, fifoBuffer);
mpu.dmpGetGravity(&gravity, &q);
mpu.dmpGetLinearAccel(&aaReal, &aa, &gravity);
// Serial.print("areal\t");
// Serial.print(aaReal.x);
// Serial.print("\t");
// Serial.print(aaReal.y);
// Serial.print("\t");
// Serial.println(aaReal.z);
#endif
#ifdef OUTPUT_READABLE_WORLDACCEL
// display initial world-frame acceleration, adjusted to remove gravity
// and rotated based on known orientation from quaternion
mpu.dmpGetQuaternion(&q, fifoBuffer);
mpu.dmpGetAccel(&aa, fifoBuffer);
mpu.dmpGetGravity(&gravity, &q);
mpu.dmpGetLinearAccel(&aaReal, &aa, &gravity);
mpu.dmpGetLinearAccelInWorld(&aaWorld, &aaReal, &q);
// Serial.print("aworld\t");
// Serial.print(aaWorld.x);
// Serial.print("\t");
// Serial.print(aaWorld.y);
// Serial.print("\t");
// Serial.println(aaWorld.z);
#endif
#ifdef OUTPUT_TEAPOT
// display quaternion values in InvenSense Teapot demo format:
teapotPacket[2] = fifoBuffer[0];
teapotPacket[3] = fifoBuffer[1];
teapotPacket[4] = fifoBuffer[4];
teapotPacket[5] = fifoBuffer[5];
teapotPacket[6] = fifoBuffer[8];
teapotPacket[7] = fifoBuffer[9];
teapotPacket[8] = fifoBuffer[12];
teapotPacket[9] = fifoBuffer[13];
Serial.write(teapotPacket, 14);
teapotPacket[11]++; // packetCount, loops at 0xFF on purpose
#endif
// blink LED to indicate activity
// blinkState = !blinkState;
// digitalWrite(LED_PIN, blinkState);
}
#endif
}
The solver I'm using is fixed-step discrete solver.
I build the S-function and then the model successfully. When I run the simulation in the external mode using Arduino mega there are jump and glitches in the output raw, pitch and roll angles as shown in the 
However, when I plotted the same code through Arduino IDE and monitor data on serial plotter there is no glitches and jumps in angles.
I have also change the baud rate to 115200, solver to auto and sample time of s-function but the problem remain to persist.
Any help would be appreciated!
Thanks in advance!
