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Thread: Can't find interrupt pin for MPU5050 tutorial.

  1. #1

    Can't find interrupt pin for MPU5050 tutorial.

    Hello-

    This should be a simple answer. I've tried everything I can think of to solve it with no luck. I'm trying to go through the mpu 6050 tutorial found here. I ran it successfully with an UNO, but I want to use it in a teensy project, so I moved everything over and its not working. I'll initialize in the serial monitor, and the device will stall out waiting for an interrupt.

    I don't know if this is a wiring issue. I've tried connecting the interrupt on the MPU 6050 to pin 0 (as it says in the code) and 2 (the pin I used on the UNO) with no luck. I went through with an alligator clip and touched it to the remaining unused pins with no luck, either, but I don't know if that was a solid connection. Also of note, I have my teensy soldered with an audio shield, which may be part of the problem? Otherwise, everything is attached the same way it was on the UNO.

    I know it says in the teensyduino reference that all digital pins can be used as interrupts, but I'm not sure if there's anything in the code I need to change. For ease, I attached the code below.

    Code:
    // I2C device class (I2Cdev) demonstration Arduino sketch for MPU6050 class using DMP (MotionApps v2.0)
    // 6/21/2012 by Jeff Rowberg <jeff@rowberg.net>
    // Updates should (hopefully) always be available at https://github.com/jrowberg/i2cdevlib
    //
    // Changelog:
    //      2013-05-08 - added seamless Fastwire support
    //                 - added note about gyro calibration
    //      2012-06-21 - added note about Arduino 1.0.1 + Leonardo compatibility error
    //      2012-06-20 - improved FIFO overflow handling and simplified read process
    //      2012-06-19 - completely rearranged DMP initialization code and simplification
    //      2012-06-13 - pull gyro and accel data from FIFO packet instead of reading directly
    //      2012-06-09 - fix broken FIFO read sequence and change interrupt detection to RISING
    //      2012-06-05 - add gravity-compensated initial reference frame acceleration output
    //                 - add 3D math helper file to DMP6 example sketch
    //                 - add Euler output and Yaw/Pitch/Roll output formats
    //      2012-06-04 - remove accel offset clearing for better results (thanks Sungon Lee)
    //      2012-06-01 - fixed gyro sensitivity to be 2000 deg/sec instead of 250
    //      2012-05-30 - basic DMP initialization working
    
    /* ============================================
    I2Cdev device library code is placed under the MIT license
    Copyright (c) 2012 Jeff Rowberg
    
    Permission is hereby granted, free of charge, to any person obtaining a copy
    of this software and associated documentation files (the "Software"), to deal
    in the Software without restriction, including without limitation the rights
    to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
    copies of the Software, and to permit persons to whom the Software is
    furnished to do so, subject to the following conditions:
    
    The above copyright notice and this permission notice shall be included in
    all copies or substantial portions of the Software.
    
    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
    AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
    LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
    OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
    THE SOFTWARE.
    ===============================================
    */
    
    // I2Cdev and MPU6050 must be installed as libraries, or else the .cpp/.h files
    // for both classes must be in the include path of your project
    #include "I2Cdev.h"
    
    #include "MPU6050_6Axis_MotionApps20.h"
    //#include "MPU6050.h" // 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"
    #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;
    //MPU6050 mpu(0x69); // <-- use for AD0 high
    
    /* =========================================================================
       NOTE: In addition to connection 3.3v, GND, SDA, and SCL, this sketch
       depends on the MPU-6050's INT pin being connected to the Arduino's
       external interrupt #0 pin. On the Arduino Uno and Mega 2560, this is
       digital I/O pin 2.
     * ========================================================================= */
    
    /* =========================================================================
       NOTE: Arduino v1.0.1 with the Leonardo board generates a compile error
       when using Serial.write(buf, len). The Teapot output uses this method.
       The solution requires a modification to the Arduino USBAPI.h file, which
       is fortunately simple, but annoying. This will be fixed in the next IDE
       release. For more info, see these links:
    
       http://arduino.cc/forum/index.php/topic,109987.0.html
       http://code.google.com/p/arduino/issues/detail?id=958
     * ========================================================================= */
    
    
    
    // uncomment "OUTPUT_READABLE_QUATERNION" if you want to see the actual
    // quaternion components in a [w, x, y, z] format (not best for parsing
    // on a remote host such as Processing or something though)
    //#define OUTPUT_READABLE_QUATERNION
    
    // uncomment "OUTPUT_READABLE_EULER" if you want to see Euler angles
    // (in degrees) calculated from the quaternions coming from the FIFO.
    // Note that Euler angles suffer from gimbal lock (for more info, see
    // http://en.wikipedia.org/wiki/Gimbal_lock)
    #define OUTPUT_READABLE_EULER
    
    // uncomment "OUTPUT_READABLE_YAWPITCHROLL" if you want to see the yaw/
    // pitch/roll angles (in degrees) calculated from the quaternions coming
    // from the FIFO. Note this also requires gravity vector calculations.
    // Also note that yaw/pitch/roll angles suffer from gimbal lock (for
    // more info, see: http://en.wikipedia.org/wiki/Gimbal_lock)
    #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 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;
    }
    
    
    
    // ================================================================
    // ===                      INITIAL SETUP                       ===
    // ================================================================
    
    void setup() {
        // 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
        // (115200 chosen because it is required for Teapot Demo output, but it's
        // really up to you depending on your project)
        Serial.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
        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"));
    
        // wait for ready
        Serial.println(F("\nSend any character to begin DMP programming and demo: "));
        while (Serial.available() && Serial.read()); // empty buffer
        while (!Serial.available());                 // wait for data
        while (Serial.available() && Serial.read()); // empty buffer again
    
        // load and configure the DMP
        Serial.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
            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;
    
            #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);
                Serial.print("ypr\t");
                Serial.print(ypr[0] * 180/M_PI);
                Serial.print("\t");
                Serial.print(ypr[1] * 180/M_PI);
                Serial.print("\t");
                Serial.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);
        }
    }

  2. #2
    Senior Member+ KurtE's Avatar
    Join Date
    Jan 2014
    Posts
    5,586
    There has been a few threads recently with people converting from Uno like to Teensy and having issues with Interrupts.

    You might do a quick search, but, the two main things that come to mind:

    a) Initial pin states are different between UNO and Teensy, where the Teensy is more or less configured by default as Inactive which saves power.
    So try adding something like: pinMode(pin, INPUT_PULLUP); or just INPUT if you have external stuff doing pullup or pull down.

    b) On Teensy attachInterrupt, the first argument is the actual pin number not some other number... There is a macro that you can use to map PIN to Interrupt to make code more portable.

  3. #3
    Thanks!

    Specifying the pinMode was crucial. I also had to adapt the code to move the interrupt information to the loop section of the code. I have attached the working code with *** in the comments to what I changed from the original that I downloaded.

    Code:
    // I2C device class (I2Cdev) demonstration Arduino sketch for MPU6050 class using DMP (MotionApps v2.0)
    // 6/21/2012 by Jeff Rowberg <jeff@rowberg.net>
    // Updates should (hopefully) always be available at https://github.com/jrowberg/i2cdevlib
    //
    // Changelog:
    //      2013-05-08 - added seamless Fastwire support
    //                 - added note about gyro calibration
    //      2012-06-21 - added note about Arduino 1.0.1 + Leonardo compatibility error
    //      2012-06-20 - improved FIFO overflow handling and simplified read process
    //      2012-06-19 - completely rearranged DMP initialization code and simplification
    //      2012-06-13 - pull gyro and accel data from FIFO packet instead of reading directly
    //      2012-06-09 - fix broken FIFO read sequence and change interrupt detection to RISING
    //      2012-06-05 - add gravity-compensated initial reference frame acceleration output
    //                 - add 3D math helper file to DMP6 example sketch
    //                 - add Euler output and Yaw/Pitch/Roll output formats
    //      2012-06-04 - remove accel offset clearing for better results (thanks Sungon Lee)
    //      2012-06-01 - fixed gyro sensitivity to be 2000 deg/sec instead of 250
    //      2012-05-30 - basic DMP initialization working
    
    /* ============================================
    I2Cdev device library code is placed under the MIT license
    Copyright (c) 2012 Jeff Rowberg
    
    Permission is hereby granted, free of charge, to any person obtaining a copy
    of this software and associated documentation files (the "Software"), to deal
    in the Software without restriction, including without limitation the rights
    to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
    copies of the Software, and to permit persons to whom the Software is
    furnished to do so, subject to the following conditions:
    
    The above copyright notice and this permission notice shall be included in
    all copies or substantial portions of the Software.
    
    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
    IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
    FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
    AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
    LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
    OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
    THE SOFTWARE.
    ===============================================
    */
    
    // I2Cdev and MPU6050 must be installed as libraries, or else the .cpp/.h files
    // for both classes must be in the include path of your project
    #include "I2Cdev.h"
    
    #include "MPU6050_6Axis_MotionApps20.h"
    //#include "MPU6050.h" // 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"
    #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;
    //MPU6050 mpu(0x69); // <-- use for AD0 high
    
    /* =========================================================================
       NOTE: In addition to connection 3.3v, GND, SDA, and SCL, this sketch
       depends on the MPU-6050's INT pin being connected to the Arduino's
       external interrupt #0 pin. On the Arduino Uno and Mega 2560, this is
       digital I/O pin 2.
     * ========================================================================= */
    
    /* =========================================================================
       NOTE: Arduino v1.0.1 with the Leonardo board generates a compile error
       when using Serial.write(buf, len). The Teapot output uses this method.
       The solution requires a modification to the Arduino USBAPI.h file, which
       is fortunately simple, but annoying. This will be fixed in the next IDE
       release. For more info, see these links:
    
       http://arduino.cc/forum/index.php/topic,109987.0.html
       http://code.google.com/p/arduino/issues/detail?id=958
     * ========================================================================= */
    
    
    
    // uncomment "OUTPUT_READABLE_QUATERNION" if you want to see the actual
    // quaternion components in a [w, x, y, z] format (not best for parsing
    // on a remote host such as Processing or something though)
    //#define OUTPUT_READABLE_QUATERNION
    
    // uncomment "OUTPUT_READABLE_EULER" if you want to see Euler angles
    // (in degrees) calculated from the quaternions coming from the FIFO.
    // Note that Euler angles suffer from gimbal lock (for more info, see
    // http://en.wikipedia.org/wiki/Gimbal_lock)
    //#define OUTPUT_READABLE_EULER
    
    // uncomment "OUTPUT_READABLE_YAWPITCHROLL" if you want to see the yaw/
    // pitch/roll angles (in degrees) calculated from the quaternions coming
    // from the FIFO. Note this also requires gravity vector calculations.
    // Also note that yaw/pitch/roll angles suffer from gimbal lock (for
    // more info, see: http://en.wikipedia.org/wiki/Gimbal_lock)
    #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 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;
    }
    
    
    
    // ================================================================
    // ===                      INITIAL SETUP                       ===
    // ================================================================
    
    void setup() {
        // 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
        // (115200 chosen because it is required for Teapot Demo output, but it's
        // really up to you depending on your project)
        Serial.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
        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"));
    
        // wait for ready
        Serial.println(F("\nSend any character to begin DMP programming and demo: "));
        while (Serial.available() && Serial.read()); // empty buffer
        while (!Serial.available());                 // wait for data
        while (Serial.available() && Serial.read()); // empty buffer again
    
        // load and configure the DMP
        Serial.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
            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);
        pinMode(0, INPUT); // *** ADDED FROM ORIGINAL CODE
    }
    
    
    
    // ================================================================
    // ===                    MAIN PROGRAM LOOP                     ===
    // ================================================================
    
    void loop() {
    
          attachInterrupt(0, dmpDataReady, RISING); // *** MOVED FROM SETUP TO 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;
    
            #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);
                Serial.print("ypr\t");
                Serial.print(ypr[0] * 180/M_PI);
                Serial.print("\t");
                Serial.print(ypr[1] * 180/M_PI);
                Serial.print("\t");
                Serial.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);
        }
    }

    Quote Originally Posted by KurtE View Post
    There has been a few threads recently with people converting from Uno like to Teensy and having issues with Interrupts.

    You might do a quick search, but, the two main things that come to mind:

    a) Initial pin states are different between UNO and Teensy, where the Teensy is more or less configured by default as Inactive which saves power.
    So try adding something like: pinMode(pin, INPUT_PULLUP); or just INPUT if you have external stuff doing pullup or pull down.

    b) On Teensy attachInterrupt, the first argument is the actual pin number not some other number... There is a macro that you can use to map PIN to Interrupt to make code more portable.

  4. #4
    Senior Member PaulStoffregen's Avatar
    Join Date
    Nov 2012
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    20,684
    Perhaps a future version of Teensy's attachInterrupt() ought to check if the pin is in low-power disable mode, and automatically use pinMode. That'd give us better compatibility with Arduino sketches that rely on the AVR's default input mode, without losing the power savings of default disable mode, and without overriding any other mode the user explicitly sets (like input pullup or input pulldown).

  5. #5
    Quote Originally Posted by PaulStoffregen View Post
    Perhaps a future version of Teensy's attachInterrupt() ought to check if the pin is in low-power disable mode, and automatically use pinMode. That'd give us better compatibility with Arduino sketches that rely on the AVR's default input mode, without losing the power savings of default disable mode, and without overriding any other mode the user explicitly sets (like input pullup or input pulldown).
    This could be helpful, but I think its more of a documentation issue than a coding one. I really appreciate the idea of you trying to make things as seamless from one platform to another, especially as a beginner with all this. I think I would have been able to solve the problem on my own though if the pinMode behavior was given a sentence or two in either the teensyduino section, the pinouts page, or the page on interrupts.

    I've also seen a few people discussing the creation of a wiki page that would aggregate a lot of this forum help, and I'd be more than happy to contribute if that became a thing. As someone new with a lot of questions, I might be useful at finding all of those neophyte stumbling blocks.

    Again, thanks for your help!

  6. #6
    Senior Member+ defragster's Avatar
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    Quote Originally Posted by lownote View Post
    ... I've also seen a few people discussing the creation of a wiki page that would aggregate a lot of this forum help ...
    Until PJRC WiKi is online this thread exists to drop links to posts like above where problems are identified or solved: Wiki-Coming-Please-link-worthy-posts Ideally when the WiKi comes online these will be migrated and expanded as appropriate.

  7. #7
    Senior Member PaulStoffregen's Avatar
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    As a quick followup on this old thread, this feature was added in Teensyduino 1.32.

    Quote Originally Posted by PaulStoffregen View Post
    Perhaps a future version of Teensy's attachInterrupt() ought to check if the pin is in low-power disable mode, and automatically use pinMode.
    Programs written for AVR Arduino boards which don't use pinMode before attachInterrupt should now work automatically.

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