need to interface nrf24l01 and mpu6050

hello !
So what I actually want to do is to send all the data from the MPU6050 (accelerometer+gyroscope) from arduino UNO to arduino MEGA2560 via NRF24l01

the codes for each individual thing (i.e

  • coomunication between both arduino by using nrf24l01
  • just obtaining output of MPU6050
    ) runs just fine.

The problem is that I dont know how to mix them together

I am attaching both the basic programs that I was able to run.

I tried this

#include "Wire.h" // This library allows you to communicate with I2C devices.
const int MPU_ADDR = 0x68; // I2C address of the MPU-6050. If AD0 pin is set to HIGH, the I2C address will be 0x69.
int16_t accelerometer_x, accelerometer_y, accelerometer_z; // variables for accelerometer raw data
int16_t gyro_x, gyro_y, gyro_z; // variables for gyro raw data
int16_t temperature; // variables for temperature data
char tmp_str[7]; // temporary variable used in convert function
char* convert_int16_to_str(int16_t i) { // converts int16 to string. Moreover, resulting strings will have the same length in the debug monitor.
  sprintf(tmp_str, "%6d", i);
  return tmp_str;
}
#include <SPI.h>
#include "nRF24L01.h"
#include "RF24.h"
#include "printf.h"

//
// Hardware configuration
//

// Set up nRF24L01 radio on SPI bus plus pins 9 & 10

RF24 radio(9, 10);

//
// Topology
//

// Radio pipe addresses for the 2 nodes to communicate.
const uint64_t pipes[2] = { 0xF0F0F0F0E1LL, 0xF0F0F0F0D2LL };

//
// Role management
//
// Set up role.  This sketch uses the same software for all the nodes
// in this system.  Doing so greatly simplifies testing.
//

// The various roles supported by this sketch
typedef enum { role_ping_out = 1, role_pong_back } role_e;

// The debug-friendly names of those roles
const char* role_friendly_name[] = { "invalid", "Ping out", "Pong back"};

// The role of the current running sketch
role_e role = role_pong_back;



void setup()
{
  //
  // Print preamble
  //

  Serial.begin(9600);
  printf_begin();
  printf("\n\rRF24/examples/GettingStarted/\n\r");
  printf("ROLE: %s\n\r", role_friendly_name[role]);
  printf("*** PRESS 'T' to begin transmitting to the other node\n\r");

  //
  // Setup and configure rf radio
  //

  radio.begin();
  radio.setAutoAck(false);

  // optionally, increase the delay between retries & # of retries
  radio.setRetries(15, 15);

  // optionally, reduce the payload size.  seems to
  // improve reliability
  //radio.setPayloadSize(8);

  //
  // Open pipes to other nodes for communication
  //

  // This simple sketch opens two pipes for these two nodes to communicate
  // back and forth.
  // Open 'our' pipe for writing
  // Open the 'other' pipe for reading, in position #1 (we can have up to 5 pipes open for reading)

  //if ( role == role_ping_out )
  {
    //radio.openWritingPipe(pipes[0]);
    radio.openReadingPipe(1, pipes[1]);
  }
  //else
  {
    //radio.openWritingPipe(pipes[1]);
    //radio.openReadingPipe(1,pipes[0]);
  }

  //
  // Start listening
  //

  radio.startListening();

  //
  // Dump the configuration of the rf unit for debugging
  //

  radio.printDetails();

  //Serial.begin(9600);
  Wire.begin();
  Wire.beginTransmission(MPU_ADDR); // Begins a transmission to the I2C slave (GY-521 board)
  Wire.write(0x6B); // PWR_MGMT_1 register
  Wire.write(0); // set to zero (wakes up the MPU-6050)
  Wire.endTransmission(true);
}


void loop()
{
  //
  // Ping out role.  Repeatedly send the current time
  //

  if (role == role_ping_out)
  {
    // First, stop listening so we can talk.
    radio.stopListening();

    Wire.beginTransmission(MPU_ADDR);
    Wire.write(0x3B); // starting with register 0x3B (ACCEL_XOUT_H) [MPU-6000 and MPU-6050 Register Map and Descriptions Revision 4.2, p.40]
    Wire.endTransmission(false); // the parameter indicates that the Arduino will send a restart. As a result, the connection is kept active.
    Wire.requestFrom(MPU_ADDR, 7 * 2, true); // request a total of 7*2=14 registers

    // "Wire.read()<<8 | Wire.read();" means two registers are read and stored in the same variable
    accelerometer_x = Wire.read() << 8 | Wire.read(); // reading registers: 0x3B (ACCEL_XOUT_H) and 0x3C (ACCEL_XOUT_L)
    accelerometer_y = Wire.read() << 8 | Wire.read(); // reading registers: 0x3D (ACCEL_YOUT_H) and 0x3E (ACCEL_YOUT_L)
    accelerometer_z = Wire.read() << 8 | Wire.read(); // reading registers: 0x3F (ACCEL_ZOUT_H) and 0x40 (ACCEL_ZOUT_L)
    temperature = Wire.read() << 8 | Wire.read(); // reading registers: 0x41 (TEMP_OUT_H) and 0x42 (TEMP_OUT_L)
    gyro_x = Wire.read() << 8 | Wire.read(); // reading registers: 0x43 (GYRO_XOUT_H) and 0x44 (GYRO_XOUT_L)
    gyro_y = Wire.read() << 8 | Wire.read(); // reading registers: 0x45 (GYRO_YOUT_H) and 0x46 (GYRO_YOUT_L)
    gyro_z = Wire.read() << 8 | Wire.read(); // reading registers: 0x47 (GYRO_ZOUT_H) and 0x48 (GYRO_ZOUT_L)

    // print out data
    Serial.print("aX = "); Serial.print(convert_int16_to_str(accelerometer_x));
    Serial.print(" | aY = "); Serial.print(convert_int16_to_str(accelerometer_y));
    Serial.print(" | aZ = "); Serial.print(convert_int16_to_str(accelerometer_z));
    // the following equation was taken from the documentation [MPU-6000/MPU-6050 Register Map and Description, p.30]
    Serial.print(" | tmp = "); Serial.print(temperature / 340.00 + 36.53);
    Serial.print(" | gX = "); Serial.print(convert_int16_to_str(gyro_x));
    Serial.print(" | gY = "); Serial.print(convert_int16_to_str(gyro_y));
    Serial.print(" | gZ = "); Serial.print(convert_int16_to_str(gyro_z));
    Serial.println();

    // Take the time, and send it.  This will block until complete
    unsigned long time = millis();
    printf("Now sending %lu...", time);
    bool ok = radio.write( &time, sizeof(unsigned long) );

    if (ok)
      printf("ok...");
    else
      printf("failed.\n\r");

    // Now, continue listening
    radio.startListening();

    // Wait here until we get a response, or timeout (250ms)
    unsigned long started_waiting_at = millis();
    bool timeout = false;
    while ( ! radio.available() && ! timeout )
      if (millis() - started_waiting_at > 200 )
        timeout = true;

    // Describe the results
    if ( timeout )
    {
      printf("Failed, response timed out.\n\r");
    }
    else
    {
      // Grab the response, compare, and send to debugging spew
      unsigned long got_time;
      radio.read( &got_time, sizeof(unsigned long) );

      // Spew it
      printf("Got response %lu, round-trip delay: %lu\n\r", got_time, millis() - got_time);
    }

    // Try again 1s later
    delay(1000);
  }

  //
  // Pong back role.  Receive each packet, dump it out, and send it back
  //

  if ( role == role_pong_back )
  {
    // if there is data ready
    if ( radio.available() )
    {
      // Dump the payloads until we've gotten everything
      unsigned long got_time;
      bool done = false;
      while (!done)
      {
        // Fetch the payload, and see if this was the last one.
        done = radio.read( &got_time, sizeof(unsigned long) );

        // Spew it
        printf("Got payload %lu...", got_time);

        // Delay just a little bit to let the other unit
        // make the transition to receiver
        delay(20);
      }

      // First, stop listening so we can talk
      radio.stopListening();

      // Send the final one back.
      radio.write( &got_time, sizeof(unsigned long) );
      printf("Sent response.\n\r");

      // Now, resume listening so we catch the next packets.
      radio.startListening();
    }
  }

  //
  // Change roles
  //

  if ( Serial.available() )
  {
    char c = toupper(Serial.read());
    if ( c == 'T' && role == role_pong_back )
    {
      printf("*** CHANGING TO TRANSMIT ROLE -- PRESS 'R' TO SWITCH BACK\n\r");

      // Become the primary transmitter (ping out)
      role = role_ping_out;
      radio.openWritingPipe(pipes[0]);
      radio.openReadingPipe(1, pipes[1]);
    }
    else if ( c == 'R' && role == role_ping_out )
    {
      printf("*** CHANGING TO RECEIVE ROLE -- PRESS 'T' TO SWITCH BACK\n\r");

      // Become the primary receiver (pong back)
      role = role_pong_back;
      radio.openWritingPipe(pipes[1]);
      radio.openReadingPipe(1, pipes[0]);
    }
  }
}

but that didnt work

gyroscope.ino (2.88 KB)

GettingStarted.ino (5.43 KB)

printf.h (657 Bytes)

Have a look at this Simple nRF24L01+ Tutorial.

Wireless problems can be very difficult to debug so get the wireless part working on its own before you start adding any other features.

The examples are as simple as I could make them and they have worked for other Forum members. If you get stuck it will be easier to help with code that I am familiar with. Start by getting the first example to work

Note that the SPI pins are in a different place on a Mega - see the SPI library documentation.

...R