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Topic: Problem with MPU6050 + NRF24l01 + Processing (Read 43 times) previous topic - next topic


Hi, I am a new member of this forum. I write here because I have a small problem with my project; in this days I am trying to send the MPU 6050 datas with the transceiver nRF24l01 to the serial port of my pc, where elaborate it as in this link: https://www.youtube.com/watch?v=nlXqIe9-R7s&t=373s. That is the code of trasmitter:

Code: [Select]

#include <SPI.h>
#include <nRF24L01.h>
#include <RF24.h>
#define CE_PIN 9
#define CSN_PIN 53

#include "I2Cdev.h"
#include "MPU6050_6Axis_MotionApps20.h"
//#include "MPU6050.h" // not necessary if using MotionApps include file
#include "Wire.h"


#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
float Z;

typedef struct{
  .   <---- not important part
C_t dati2;

// orientation/motion vars
Quaternion q;          
VectorInt16 aa;        
VectorInt16 aaReal;  
VectorInt16 aaWorld;    
VectorFloat gravity;    
float euler[3];        
float ypr[3];          

uint8_t teapotPacket[14] = { '$', 0x02, 0,0, 0,0, 0,0, 0,0, 0x00, 0x00, '\r', '\n' };

RF24 radio(CE_PIN, CSN_PIN);
const uint64_t pipes[2] = {
  0xF0F0F0F0E1LL, 0xF0F0F0F0D2LL };

// interrupt detection routine
volatile bool mpuInterrupt = false;     // indicates whether MPU interrupt pin has gone high
void dmpDataReady() {
    mpuInterrupt = true;

void setup() {
    // join I2C bus (I2Cdev library doesn't do this automatically)
        Wire.setClock(400000); // 400kHz I2C clock. Comment this line if having compilation difficulties
        Fastwire::setup(400, true);

    while (!Serial);

    // initialize device
    Serial.println(F("Initializing I2C devices..."));
    pinMode(10, OUTPUT);

    // verify connection
    Serial.println(F("Testing device connections..."));
    Serial.println(mpu.testConnection() ? F("MPU6050 connection successful") : F("MPU6050 connection failed"));

    // load and configure the DMP
    Serial.println(F("Initializing DMP..."));
    devStatus = mpu.dmpInitialize();

    // supply your own gyro offsets here, scaled for min sensitivity
    // 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..."));

        // enable Arduino interrupt detection
        Serial.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
        Serial.println(F("DMP ready! Waiting for first interrupt..."));               <--------------- block point
        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 "));

    // configure LED for output
    pinMode(LED_PIN, OUTPUT);
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)
    // 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
        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 quaternion values in easy matrix form: w x y z
            mpu.dmpGetQuaternion(&q, fifoBuffer);

            // display Euler angles in degrees
            mpu.dmpGetQuaternion(&q, fifoBuffer);
            mpu.dmpGetEuler(euler, &q);

            // display Euler angles in degrees
            mpu.dmpGetQuaternion(&q, fifoBuffer);
            mpu.dmpGetGravity(&gravity, &q);
            mpu.dmpGetYawPitchRoll(ypr, &q, &gravity);

            // display real acceleration, adjusted to remove gravity
            mpu.dmpGetQuaternion(&q, fifoBuffer);
            mpu.dmpGetAccel(&aa, fifoBuffer);
            mpu.dmpGetGravity(&gravity, &q);
            mpu.dmpGetLinearAccel(&aaReal, &aa, &gravity);
            aaReal.y = abs(aaReal.y);
            aaReal.y = ((aaReal.y * 9.8) / 60);

            // 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);

            dati.tP2 = fifoBuffer[0];
            dati.tP3 = fifoBuffer[1];
            dati.tP4 = fifoBuffer[4];
            dati.tP5 = fifoBuffer[5];
            dati1.tP6 = fifoBuffer[8];
            dati1.tP7 = fifoBuffer[9];
            dati1.tP8 = fifoBuffer[12];
            dati1.tP9 = fifoBuffer[13];
            dati2.q0 = q.w;
            dati2.q1 = q.x;
            dati2.q2 = q.y;
            dati2.q3 = q.z;
            radio.write(&dati, sizeof(dati));
            radio.write(&dati1, sizeof(dati1));         //  <------  this part
            radio.write(&dati2, sizeof(dati2));  
        // blink LED to indicate activity
        blinkState = !blinkState;
        digitalWrite(LED_PIN, blinkState);

The problem arises when I include the function radio.write, blocking code at the comand : Serial.println(F("DMP ready! Waiting for first interrupt..."));    

Code start if I take off the 3 function "radio.write", obviously without sending nothing.
If someone identify the problem I would be very grateful.

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