Hi!
I'm trying to communicate with the MPU6050 in MATLAB, where if I send a request 'A' via serial bluetooth to the Arduino UNO, I get the current reading of the euler angle. This kind of works for me at the moment, but if I request the serial print out of the angle too many times in a row, or to frequently, I get some kind of FIFO overflow, so that I have to reset the arduino and re-initialize the Bluetooth connection before I can use it again. It usually takes less than 5-10 requests before the MPU hangs and does not respond anymore. I'll post my arduino code below. I reqest the angle by sending the character 'A' via bluetooth to the arduino. In the same way, I use a motor shield so that I can control two DC-motors that are connected to the arduino as well, by sending various commands via bluetooth.
#include <SoftwareSerial.h>
SoftwareSerial BT(5, 6);
// creates a "virtual" serial port/UART
// connect BT module TX to D5
// connect BT module RX to D6
// connect BT Vcc to 3.3V, GND to GND
#include "I2Cdev.h"
#include "MPU6050_6Axis_MotionApps20.h"
#if I2CDEV_IMPLEMENTATION == I2CDEV_ARDUINO_WIRE
#include "Wire.h"
#endif
MPU6050 mpu;
#define OUTPUT_READABLE_EULER
#define LED_PIN 13 //
char val = 0;
int speed = 40;
int a =0;
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
int angle;
// 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
// ================================================================
// === INTERRUPT DETECTION ROUTINE ===
// ================================================================
volatile bool mpuInterrupt = false; // indicates whether MPU interrupt pin has gone high
void dmpDataReady() {
mpuInterrupt = true;
}
// ================================================================
// === INITIAL SETUP ===
// ================================================================
void setup() {
//Setup Channel A
pinMode(12, OUTPUT); //Initiates Motor Channel A pin
pinMode(9, OUTPUT); //Initiates Brake Channel A pin
// 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
// initialize serial communication
// Serial.begin(9600);
BT.begin(9600);
while (!Serial); // wait for Leonardo enumeration, others continue immediately
mpu.initialize();
devStatus = mpu.dmpInitialize();
// supply your own gyro offsets here, scaled for min sensitivity
mpu.setXGyroOffset(38);
mpu.setYGyroOffset(-91);
mpu.setZGyroOffset(46);
mpu.setZAccelOffset(1682); // 1688 factory default for my test chip
// make sure it worked (returns 0 if so)
if (devStatus == 0) {
mpu.setDMPEnabled(true);
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() {
// MPU run
// 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)
{
if (BT.available() )
{
val = BT.read();
if (val == 'F')
{
//forward @ speed 40
digitalWrite(12, HIGH); //Establishes forward direction of Channel A
digitalWrite(13, LOW); //Establishes forward direction of Channel B
digitalWrite(9, LOW); //Disengage the Brake for Channel A
digitalWrite(8, LOW); //Disengage the Brake for Channel B
analogWrite(3, speed); //Spins the motor on Channel A at speed 50. (full speed = 255) (variable speed defined at 50 as standard)
analogWrite(11, speed); //Spins motor Channel B at speed 20.
}
else if(val == 'G')
{
//Backwards @ speed 40
digitalWrite(12, LOW); //Establishes Backwards direction of Channel A
digitalWrite(13, HIGH); //Establishes Backwards direction of Channel B
digitalWrite(9, LOW); //Disengage the Brake for Channel A
digitalWrite(8, LOW); //Disengage the Brake for Channel B
analogWrite(3, speed); //Spins the motor on Channel A at speed 40. (full speed = 255) (variable speed defined at 50 as standard)
analogWrite(11, speed); //Spins motor Channel B at speed 40
}
else if (val == 'B'){
//Breaks both Channels
digitalWrite(9, HIGH); //Eengage the Brake for Channel A
digitalWrite(8, HIGH); //Eengage the Brake for Channel B
}
else if (val == 'L'){
//Turn left @ speed 20
digitalWrite(12, HIGH); //Establishes forward direction of Channel A
digitalWrite(9, LOW); //Disengage the Brake for Channel A
digitalWrite(8, HIGH); //Engage the Brake for Channel B
analogWrite(3, speed); //Spins the motor on Channel A at speed 40. (full speed = 255)
}
else if (val == 'R'){
//Turn left @ speed 20
digitalWrite(13, LOW); //Establishes forward direction of Channel B
digitalWrite(8, LOW); //Disengage the Brake for Channel B
digitalWrite(9, HIGH); //Engage the Brake for Channel A
analogWrite(11, speed); //Spins the motor on Channel A at speed 40. (full speed = 255)
}
else if (val == 'A')
{
// display Euler angles in degrees
mpu.dmpGetQuaternion(&q, fifoBuffer);
mpu.dmpGetEuler(euler, &q);
// Serial.print("\n");
BT.println(euler[0] * 180/M_PI);
// Serial.print(euler[1] * 180/M_PI);
// Serial.print("\t");
// Serial.println(euler[2] * 180/M_PI);
// blink LED to indicate activity
blinkState = !blinkState;
digitalWrite(LED_PIN, blinkState);
}
}
}
// 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;
}
}
