MPU and bluetooth freezing after a few seconds

Hi all, I am using a Ardunio nano, MPU5060 and a HC-05 bluetooth module to connect my Arduino project to my android phone via the Blynk app. The Idea is to eventually send data to the Blynk app and plot a graph.

Initially I spit the code into two sections, the first being to test the MPU and the second to test the connectivity between the HC-05 and the Blynk app. Individually they both work well, the MPU provides constant gyro data and the Bluetooth module allows me to activate D13 LED pin from the Blynk app.

Now the issue comes when I combine these two pieces of code. It starts of fine but within a few second everything becomes unresponsive and freezes. I am then unable to see the gyro data in the serial monitor and I am no longer able to control the D13 LED. Please see below combined code.

#include "I2Cdev.h"
#include "MPU6050_6Axis_MotionApps20.h"
#if I2CDEV_IMPLEMENTATION == I2CDEV_ARDUINO_WIRE
#include "Wire.h"
#endif

MPU6050 mpu;

#define OUTPUT_READABLE_YAWPITCHROLL

#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


//Calibration
float RollCalibrationReading;  // initial roll reading before calibration, this value is used for calibrtion
float RollValue;  // Roll angle
float CallibrationAdjustment; // Calibration adjustment
boolean RunCalibration = false;  // has calibration run yet

// Handstand
boolean standStatus;

// timing
unsigned long startMillis;
unsigned long currentMillis;
unsigned long strandStartTime;
unsigned long standDuration;

// packet structure for InvenSense teapot demo
uint8_t teapotPacket[14] = { '

I am a little out of my depth here and I have tried trouble shooting by removing section of code and trying to isolate the issue but i'm totally stomped. Any advise or help in solving this would be greatly appreciated.

, 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;
}
// ================================================================
// ===               BLUETOOTH SETUP                            ===
// ================================================================
#define BLYNK_PRINT Serial

#include <SoftwareSerial.h>
SoftwareSerial SwSerial(7, 8); // RX, TX
   
#include <BlynkSimpleSerialBLE.h>
#include <SoftwareSerial.h>

// You should get Auth Token in the Blynk App.
// Go to the Project Settings (nut icon).
char auth[] = "my auth code";

SoftwareSerial SerialBLE(7, 8); // RX, TX

// ================================================================
// ===                      INITIAL SETUP                       ===
// ================================================================

void setup() {

// bluetooth
 Serial.begin(9600);

SerialBLE.begin(9600);
 Blynk.begin(SerialBLE, auth);

Serial.println("Connected");
 
 pinMode(12, OUTPUT);
 pinMode(13, OUTPUT);
 digitalWrite(13, HIGH);
 Serial.println("Start testing LED");
// bluetooth

startMillis = millis();

// join I2C bus (I2Cdev library doesn't do this automatically)
#if I2CDEV_IMPLEMENTATION == I2CDEV_ARDUINO_WIRE
 Wire.begin();
 TWBR = 24; // 400kHz I2C clock (200kHz if CPU is 8MHz)
#elif I2CDEV_IMPLEMENTATION == I2CDEV_BUILTIN_FASTWIRE
 Fastwire::setup(400, true);
#endif

Serial.begin(9600);
 while (!Serial); // wait for Leonardo enumeration, others continue immediately
u.initialize();

devStatus = mpu.dmpInitialize();

// supply your own gyro offsets here, scaled for min sensitivity
 mpu.setXGyroOffset(138);
 mpu.setYGyroOffset(-37);
 mpu.setZGyroOffset(41);
 mpu.setZAccelOffset(1338); // 1688 factory default for my test chip

// make sure it worked (returns 0 if so)

// turn on the DMP, now that it's ready
 mpu.setDMPEnabled(true);

// enable Arduino interrupt detection
 attachInterrupt(0, dmpDataReady, RISING);
 mpuIntStatus = mpu.getIntStatus();

// set our DMP Ready flag so the main loop() function knows it's okay to use it
 dmpReady = true;

// get expected DMP packet size for later comparison
 packetSize = mpu.dmpGetFIFOPacketSize();

}

// ================================================================
// ===                    MAIN PROGRAM LOOP                     ===
// ================================================================

void loop() {

Blynk.run();

currentMillis = millis();

// 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) {
 }

// 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.dmpGetGravity(&gravity, &q);
   mpu.dmpGetYawPitchRoll(ypr, &q, &gravity);

RollValue = (ypr[2] * 180 / M_PI);

if ((RunCalibration == false) && (currentMillis - startMillis >= 2000)) //optimum millis 5000
   {
     Calibration();
   }
   else if (RunCalibration == true) {

TestMeasurements();
   }
 }
}

// ================================================================
// ===                      CALIBRATION FUNCTION                ===
// ================================================================

void Calibration()
{
 //Calibration reading

RollCalibrationReading = (ypr[2] * 180 / M_PI);
 if ((RollCalibrationReading >= 0)&&(RollCalibrationReading <= 180)){
   CallibrationAdjustment = RollCalibrationReading;
 }
 else if ((RollCalibrationReading > 180)&&(RollCalibrationReading <= 360)){
   CallibrationAdjustment = RollCalibrationReading - 360;
 }

//Take calibration reading once
 Serial.print("Calibdarion value");
 Serial.println(CallibrationAdjustment);
 Serial.print("Time");
 Serial.println(currentMillis);
 Serial.println("");

RunCalibration = true;
}

// ================================================================
// ===                      TEST MEAUSREMENTS                   ===
// ================================================================

void TestMeasurements() {
 //Serial.print("rool value before calibration\t");
 //Serial.println(ypr[2] * 180 / M_PI);
 //Serial.print("roll angle after calibration\t");
 Serial.println(RollValue);

//Serial.print("\t");
 //Serial.println(currentMillis);
}


I am a little out of my depth here and I have tried trouble shooting by removing section of code and trying to isolate the issue but i'm totally stomped. Any advise or help in solving this would be greatly appreciated.

You're using SoftwareSerial in a sketch that depends on interrupts to work reliably. That doesn't work because SoftwareSerial blocks all interrupts during send out and reception of complete bytes. With 9600 baud the transfer of one byte uses more than 1ms which is a very long time frame in Arduino units.

The following code blocks infinitely if an interrupt is missed:

  while (!mpuInterrupt && fifoCount < packetSize) {
  }

fifoCount will never update because the loop is empty.

I would immolate the debugging channel and connect the HC-05 to the hardware serial interface.

Thanks for the help. I will do some more research based on your suggestions and give it another shot!

Much appreciated!