user27917: I have the library RF24 and everything in my arduino library but for some reason it's not compiling.  I don't know why. I posted the code and also the error message that the arduin IDE keeps showing. Please help me figure out whats wrong!
Arduino: 1.6.12 (Windows 7), Board: "Arduino/Genuino Uno"

libraries\RF24-master\RF24.cpp.o (symbol from plugin): In function `RF24::csn(bool)':

(.text+0x0): multiple definition of `RF24::read_register(unsigned char, unsigned char*, unsigned char)'

libraries\RF24ArduinoCommunicator-master\RF24.cpp.o (symbol from plugin):(.text+0x0): first defined here

libraries\RF24-master\RF24.cpp.o (symbol from plugin): In function `RF24::csn(bool)':

(.text+0x0): multiple definition of `RF24::read_register(unsigned char)'

libraries\RF24ArduinoCommunicator-master\RF24.cpp.o (symbol from plugin):(.text+0x0): first defined here

libraries\RF24-master\RF24.cpp.o (symbol from plugin): In function `RF24::csn(bool)':

(.text+0x0): multiple definition of `RF24::write_register(unsigned char, unsigned char const*, unsigned char)'

libraries\RF24ArduinoCommunicator-master\RF24.cpp.o (symbol from plugin):(.text+0x0): first defined here

libraries\RF24-master\RF24.cpp.o (symbol from plugin): In function `RF24::csn(bool)':

(.text+0x0): multiple definition of `RF24::write_register(unsigned char, unsigned char)'

libraries\RF24ArduinoCommunicator-master\RF24.cpp.o (symbol from plugin):(.text+0x0): first defined here

libraries\RF24-master\RF24.cpp.o (symbol from plugin): In function `RF24::csn(bool)':

(.text+0x0): multiple definition of `RF24::openReadingPipe(unsigned char, unsigned long long)'

libraries\RF24ArduinoCommunicator-master\RF24.cpp.o (symbol from plugin):(.text+0x0): first defined here

libraries\RF24-master\RF24.cpp.o (symbol from plugin): In function `RF24::csn(bool)':

(.text+0x0): multiple definition of `RF24::setAutoAck(bool)'

libraries\RF24ArduinoCommunicator-master\RF24.cpp.o (symbol from plugin):(.text+0x0): first defined here

libraries\RF24-master\RF24.cpp.o (symbol from plugin): In function `RF24::csn(bool)':

(.text+0x0): multiple definition of `RF24::setAutoAck(unsigned char, bool)'

libraries\RF24ArduinoCommunicator-master\RF24.cpp.o (symbol from plugin):(.text+0x0): first defined here

libraries\RF24-master\RF24.cpp.o (symbol from plugin): In function `RF24::csn(bool)':

(.text+0x0): multiple definition of `RF24::read_payload(void*, unsigned char)'

libraries\RF24ArduinoCommunicator-master\RF24.cpp.o (symbol from plugin):(.text+0x0): first defined here

libraries\RF24-master\RF24.cpp.o (symbol from plugin): In function `RF24::csn(bool)':

(.text+0x0): multiple definition of `RF24::flush_rx()'

libraries\RF24ArduinoCommunicator-master\RF24.cpp.o (symbol from plugin):(.text+0x0): first defined here

libraries\RF24-master\RF24.cpp.o (symbol from plugin): In function `RF24::csn(bool)':

(.text+0x0): multiple definition of `RF24::getDynamicPayloadSize()'

libraries\RF24ArduinoCommunicator-master\RF24.cpp.o (symbol from plugin):(.text+0x0): first defined here

libraries\RF24-master\RF24.cpp.o (symbol from plugin): In function `RF24::csn(bool)':

(.text+0x0): multiple definition of `RF24::flush_tx()'

libraries\RF24ArduinoCommunicator-master\RF24.cpp.o (symbol from plugin):(.text+0x0): first defined here

libraries\RF24-master\RF24.cpp.o (symbol from plugin): In function `RF24::csn(bool)':

(.text+0x0): multiple definition of `RF24::get_status()'

libraries\RF24ArduinoCommunicator-master\RF24.cpp.o (symbol from plugin):(.text+0x0): first defined here

libraries\RF24-master\RF24.cpp.o (symbol from plugin): In function `RF24::csn(bool)':

(.text+0x0): multiple definition of `RF24::available(unsigned char*)'

libraries\RF24ArduinoCommunicator-master\RF24.cpp.o (symbol from plugin):(.text+0x0): first defined here

libraries\RF24-master\RF24.cpp.o (symbol from plugin): In function `RF24::csn(bool)':

(.text+0x0): multiple definition of `RF24::print_status(unsigned char)'

libraries\RF24ArduinoCommunicator-master\RF24.cpp.o (symbol from plugin):(.text+0x0): first defined here

libraries\RF24-master\RF24.cpp.o (symbol from plugin): In function `RF24::csn(bool)':

(.text+0x0): multiple definition of `RF24::print_observe_tx(unsigned char)'

libraries\RF24ArduinoCommunicator-master\RF24.cpp.o (symbol from plugin):(.text+0x0): first defined here

libraries\RF24-master\RF24.cpp.o (symbol from plugin): In function `RF24::csn(bool)':

(.text+0x0): multiple definition of `RF24::print_byte_register(char const*, unsigned char, unsigned char)'

libraries\RF24ArduinoCommunicator-master\RF24.cpp.o (symbol from plugin):(.text+0x0): first defined here

libraries\RF24-master\RF24.cpp.o (symbol from plugin): In function `RF24::csn(bool)':

(.text+0x0): multiple definition of `RF24::print_address_register(char const*, unsigned char, unsigned char)'

libraries\RF24ArduinoCommunicator-master\RF24.cpp.o (symbol from plugin):(.text+0x0): first defined here

libraries\RF24-master\RF24.cpp.o (symbol from plugin): In function `RF24::csn(bool)':

(.text+0x0): multiple definition of `RF24::RF24(unsigned char, unsigned char)'

libraries\RF24ArduinoCommunicator-master\RF24.cpp.o (symbol from plugin):(.text+0x0): first defined here

libraries\RF24-master\RF24.cpp.o (symbol from plugin): In function `RF24::csn(bool)':

(.text+0x0): multiple definition of `RF24::RF24(unsigned char, unsigned char)'

libraries\RF24ArduinoCommunicator-master\RF24.cpp.o (symbol from plugin):(.text+0x0): first defined here

libraries\RF24-master\RF24.cpp.o (symbol from plugin): In function `RF24::csn(bool)':

(.text+0x0): multiple definition of `RF24::setChannel(unsigned char)'

libraries\RF24ArduinoCommunicator-master\RF24.cpp.o (symbol from plugin):(.text+0x0): first defined here

libraries\RF24-master\RF24.cpp.o (symbol from plugin): In function `RF24::csn(bool)':

(.text+0x0): multiple definition of `RF24::setPayloadSize(unsigned char)'

libraries\RF24ArduinoCommunicator-master\RF24.cpp.o (symbol from plugin):(.text+0x0): first defined here

libraries\RF24-master\RF24.cpp.o (symbol from plugin): In function `RF24::csn(bool)':

(.text+0x0): multiple definition of `RF24::getPayloadSize()'

libraries\RF24ArduinoCommunicator-master\RF24.cpp.o (symbol from plugin):(.text+0x0): first defined here

libraries\RF24-master\RF24.cpp.o (symbol from plugin): In function `RF24::csn(bool)':

(.text+0x0): multiple definition of `RF24::stopListening()'

libraries\RF24ArduinoCommunicator-master\RF24.cpp.o (symbol from plugin):(.text+0x0): first defined here

libraries\RF24-master\RF24.cpp.o (symbol from plugin): In function `RF24::csn(bool)':

(.text+0x0): multiple definition of `RF24::powerDown()'

libraries\RF24ArduinoCommunicator-master\RF24.cpp.o (symbol from plugin):(.text+0x0): first defined here

libraries\RF24-master\RF24.cpp.o (symbol from plugin): In function `RF24::csn(bool)':

(.text+0x0): multiple definition of `RF24::powerUp()'

libraries\RF24ArduinoCommunicator-master\RF24.cpp.o (symbol from plugin):(.text+0x0): first defined here

libraries\RF24-master\RF24.cpp.o (symbol from plugin): In function `RF24::csn(bool)':

(.text+0x0): multiple definition of `RF24::write(void const*, unsigned char)'

libraries\RF24ArduinoCommunicator-master\RF24.cpp.o (symbol from plugin):(.text+0x0): first defined here

libraries\RF24-master\RF24.cpp.o (symbol from plugin): In function `RF24::csn(bool)':

(.text+0x0): multiple definition of `RF24::available()'

libraries\RF24ArduinoCommunicator-master\RF24.cpp.o (symbol from plugin):(.text+0x0): first defined here

libraries\RF24-master\RF24.cpp.o (symbol from plugin): In function `RF24::csn(bool)':

(.text+0x0): multiple definition of `RF24::read(void*, unsigned char)'

libraries\RF24ArduinoCommunicator-master\RF24.cpp.o (symbol from plugin):(.text+0x0): first defined here

libraries\RF24-master\RF24.cpp.o (symbol from plugin): In function `RF24::csn(bool)':

(.text+0x0): multiple definition of `RF24::whatHappened(bool&, bool&, bool&)'

libraries\RF24ArduinoCommunicator-master\RF24.cpp.o (symbol from plugin):(.text+0x0): first defined here

libraries\RF24-master\RF24.cpp.o (symbol from plugin): In function `RF24::csn(bool)':

(.text+0x0): multiple definition of `RF24::openWritingPipe(unsigned long long)'

libraries\RF24ArduinoCommunicator-master\RF24.cpp.o (symbol from plugin):(.text+0x0): first defined here

libraries\RF24-master\RF24.cpp.o (symbol from plugin): In function `RF24::csn(bool)':

(.text+0x0): multiple definition of `RF24::startListening()'

libraries\RF24ArduinoCommunicator-master\RF24.cpp.o (symbol from plugin):(.text+0x0): first defined here

libraries\RF24-master\RF24.cpp.o (symbol from plugin): In function `RF24::csn(bool)':

(.text+0x0): multiple definition of `RF24::toggle_features()'

libraries\RF24ArduinoCommunicator-master\RF24.cpp.o (symbol from plugin):(.text+0x0): first defined here

libraries\RF24-master\RF24.cpp.o (symbol from plugin): In function `RF24::csn(bool)':

(.text+0x0): multiple definition of `RF24::enableDynamicPayloads()'

libraries\RF24ArduinoCommunicator-master\RF24.cpp.o (symbol from plugin):(.text+0x0): first defined here

libraries\RF24-master\RF24.cpp.o (symbol from plugin): In function `RF24::csn(bool)':

(.text+0x0): multiple definition of `RF24::enableAckPayload()'

libraries\RF24ArduinoCommunicator-master\RF24.cpp.o (symbol from plugin):(.text+0x0): first defined here

libraries\RF24-master\RF24.cpp.o (symbol from plugin): In function `RF24::csn(bool)':

(.text+0x0): multiple definition of `RF24::writeAckPayload(unsigned char, void const*, unsigned char)'

libraries\RF24ArduinoCommunicator-master\RF24.cpp.o (symbol from plugin):(.text+0x0): first defined here

libraries\RF24-master\RF24.cpp.o (symbol from plugin): In function `RF24::csn(bool)':

(.text+0x0): multiple definition of `RF24::isAckPayloadAvailable()'

libraries\RF24ArduinoCommunicator-master\RF24.cpp.o (symbol from plugin):(.text+0x0): first defined here

libraries\RF24-master\RF24.cpp.o (symbol from plugin): In function `RF24::csn(bool)':

(.text+0x0): multiple definition of `RF24::isPVariant()'

libraries\RF24ArduinoCommunicator-master\RF24.cpp.o (symbol from plugin):(.text+0x0): first defined here

libraries\RF24-master\RF24.cpp.o (symbol from plugin): In function `RF24::csn(bool)':

(.text+0x0): multiple definition of `RF24::testCarrier()'

libraries\RF24ArduinoCommunicator-master\RF24.cpp.o (symbol from plugin):(.text+0x0): first defined here

libraries\RF24-master\RF24.cpp.o (symbol from plugin): In function `RF24::csn(bool)':

(.text+0x0): multiple definition of `RF24::testRPD()'

libraries\RF24ArduinoCommunicator-master\RF24.cpp.o (symbol from plugin):(.text+0x0): first defined here

libraries\RF24-master\RF24.cpp.o (symbol from plugin): In function `RF24::csn(bool)':

(.text+0x0): multiple definition of `RF24::getPALevel()'

libraries\RF24ArduinoCommunicator-master\RF24.cpp.o (symbol from plugin):(.text+0x0): first defined here

libraries\RF24-master\RF24.cpp.o (symbol from plugin): In function `RF24::csn(bool)':

(.text+0x0): multiple definition of `RF24::setDataRate(rf24_datarate_e)'

libraries\RF24ArduinoCommunicator-master\RF24.cpp.o (symbol from plugin):(.text+0x0): first defined here

libraries\RF24-master\RF24.cpp.o (symbol from plugin): In function `RF24::csn(bool)':

(.text+0x0): multiple definition of `RF24::getDataRate()'

libraries\RF24ArduinoCommunicator-master\RF24.cpp.o (symbol from plugin):(.text+0x0): first defined here

libraries\RF24-master\RF24.cpp.o (symbol from plugin): In function `RF24::csn(bool)':

(.text+0x0): multiple definition of `RF24::setCRCLength(rf24_crclength_e)'

libraries\RF24ArduinoCommunicator-master\RF24.cpp.o (symbol from plugin):(.text+0x0): first defined here

libraries\RF24-master\RF24.cpp.o (symbol from plugin): In function `RF24::csn(bool)':

(.text+0x0): multiple definition of `RF24::getCRCLength()'

libraries\RF24ArduinoCommunicator-master\RF24.cpp.o (symbol from plugin):(.text+0x0): first defined here

libraries\RF24-master\RF24.cpp.o (symbol from plugin): In function `RF24::csn(bool)':

(.text+0x0): multiple definition of `RF24::printDetails()'

libraries\RF24ArduinoCommunicator-master\RF24.cpp.o (symbol from plugin):(.text+0x0): first defined here

libraries\RF24-master\RF24.cpp.o (symbol from plugin): In function `RF24::csn(bool)':

(.text+0x0): multiple definition of `RF24::disableCRC()'

libraries\RF24ArduinoCommunicator-master\RF24.cpp.o (symbol from plugin):(.text+0x0): first defined here

libraries\RF24-master\RF24.cpp.o (symbol from plugin): In function `RF24::csn(bool)':

(.text+0x0): multiple definition of `RF24::setRetries(unsigned char, unsigned char)'

libraries\RF24ArduinoCommunicator-master\RF24.cpp.o (symbol from plugin):(.text+0x0): first defined here

libraries\RF24-master\RF24.cpp.o (symbol from plugin): In function `RF24::csn(bool)':

(.text+0x0): multiple definition of `RF24::begin()'

libraries\RF24ArduinoCommunicator-master\RF24.cpp.o (symbol from plugin):(.text+0x0): first defined here

collect2.exe: error: ld returned 1 exit status

Multiple libraries were found for "nRF24L01.h"
 Used: C:\Users\Owner\Documents\Arduino\libraries\RF24ArduinoCommunicator-master
 Not used: C:\Users\Owner\Documents\Arduino\libraries\RF24-master
 Not used: C:\Users\Owner\Documents\Arduino\libraries\RF24-master
 Not used: C:\Users\Owner\Documents\Arduino\libraries\RF24-master
 Not used: C:\Users\Owner\Documents\Arduino\libraries\RF24-master
exit status 1
Error compiling for board Arduino/Genuino Uno.

This report would have more information with
"Show verbose output during compilation"
option enabled in File -> Preferences.

Example I tried to compile:
/*
 Copyright (C) 2011 J. Coliz <maniacbug@ymail.com>

 This program is free software; you can redistribute it and/or
 modify it under the terms of the GNU General Public License
 version 2 as published by the Free Software Foundation.
 */

#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(void)
{
  //
  // Print preamble
  //

  Serial.begin(57600);
  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();

  // 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();
}

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

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

    // 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]);
    }
  }
}


user11529: You have multiple copies of the library.
Delete the folder located at:
C:\Users\Owner\Documents\Arduino\libraries\RF24ArduinoCommunicator-master


27917: <p>I have the library RF24 and everything in my arduino library but for some reason it's not compiling.  I don't know why. I posted the code and also the error message that the arduin IDE keeps showing. Please help me figure out whats wrong!</p>

<pre><code>Arduino: 1.6.12 (Windows 7), Board: "Arduino/Genuino Uno"

libraries\RF24-master\RF24.cpp.o (symbol from plugin): In function `RF24::csn(bool)':

(.text+0x0): multiple definition of `RF24::read_register(unsigned char, unsigned char*, unsigned char)'

libraries\RF24ArduinoCommunicator-master\RF24.cpp.o (symbol from plugin):(.text+0x0): first defined here

libraries\RF24-master\RF24.cpp.o (symbol from plugin): In function `RF24::csn(bool)':

(.text+0x0): multiple definition of `RF24::read_register(unsigned char)'

libraries\RF24ArduinoCommunicator-master\RF24.cpp.o (symbol from plugin):(.text+0x0): first defined here

libraries\RF24-master\RF24.cpp.o (symbol from plugin): In function `RF24::csn(bool)':

(.text+0x0): multiple definition of `RF24::write_register(unsigned char, unsigned char const*, unsigned char)'

libraries\RF24ArduinoCommunicator-master\RF24.cpp.o (symbol from plugin):(.text+0x0): first defined here

libraries\RF24-master\RF24.cpp.o (symbol from plugin): In function `RF24::csn(bool)':

(.text+0x0): multiple definition of `RF24::write_register(unsigned char, unsigned char)'

libraries\RF24ArduinoCommunicator-master\RF24.cpp.o (symbol from plugin):(.text+0x0): first defined here

libraries\RF24-master\RF24.cpp.o (symbol from plugin): In function `RF24::csn(bool)':

(.text+0x0): multiple definition of `RF24::openReadingPipe(unsigned char, unsigned long long)'

libraries\RF24ArduinoCommunicator-master\RF24.cpp.o (symbol from plugin):(.text+0x0): first defined here

libraries\RF24-master\RF24.cpp.o (symbol from plugin): In function `RF24::csn(bool)':

(.text+0x0): multiple definition of `RF24::setAutoAck(bool)'

libraries\RF24ArduinoCommunicator-master\RF24.cpp.o (symbol from plugin):(.text+0x0): first defined here

libraries\RF24-master\RF24.cpp.o (symbol from plugin): In function `RF24::csn(bool)':

(.text+0x0): multiple definition of `RF24::setAutoAck(unsigned char, bool)'

libraries\RF24ArduinoCommunicator-master\RF24.cpp.o (symbol from plugin):(.text+0x0): first defined here

libraries\RF24-master\RF24.cpp.o (symbol from plugin): In function `RF24::csn(bool)':

(.text+0x0): multiple definition of `RF24::read_payload(void*, unsigned char)'

libraries\RF24ArduinoCommunicator-master\RF24.cpp.o (symbol from plugin):(.text+0x0): first defined here

libraries\RF24-master\RF24.cpp.o (symbol from plugin): In function `RF24::csn(bool)':

(.text+0x0): multiple definition of `RF24::flush_rx()'

libraries\RF24ArduinoCommunicator-master\RF24.cpp.o (symbol from plugin):(.text+0x0): first defined here

libraries\RF24-master\RF24.cpp.o (symbol from plugin): In function `RF24::csn(bool)':

(.text+0x0): multiple definition of `RF24::getDynamicPayloadSize()'

libraries\RF24ArduinoCommunicator-master\RF24.cpp.o (symbol from plugin):(.text+0x0): first defined here

libraries\RF24-master\RF24.cpp.o (symbol from plugin): In function `RF24::csn(bool)':

(.text+0x0): multiple definition of `RF24::flush_tx()'

libraries\RF24ArduinoCommunicator-master\RF24.cpp.o (symbol from plugin):(.text+0x0): first defined here

libraries\RF24-master\RF24.cpp.o (symbol from plugin): In function `RF24::csn(bool)':

(.text+0x0): multiple definition of `RF24::get_status()'

libraries\RF24ArduinoCommunicator-master\RF24.cpp.o (symbol from plugin):(.text+0x0): first defined here

libraries\RF24-master\RF24.cpp.o (symbol from plugin): In function `RF24::csn(bool)':

(.text+0x0): multiple definition of `RF24::available(unsigned char*)'

libraries\RF24ArduinoCommunicator-master\RF24.cpp.o (symbol from plugin):(.text+0x0): first defined here

libraries\RF24-master\RF24.cpp.o (symbol from plugin): In function `RF24::csn(bool)':

(.text+0x0): multiple definition of `RF24::print_status(unsigned char)'

libraries\RF24ArduinoCommunicator-master\RF24.cpp.o (symbol from plugin):(.text+0x0): first defined here

libraries\RF24-master\RF24.cpp.o (symbol from plugin): In function `RF24::csn(bool)':

(.text+0x0): multiple definition of `RF24::print_observe_tx(unsigned char)'

libraries\RF24ArduinoCommunicator-master\RF24.cpp.o (symbol from plugin):(.text+0x0): first defined here

libraries\RF24-master\RF24.cpp.o (symbol from plugin): In function `RF24::csn(bool)':

(.text+0x0): multiple definition of `RF24::print_byte_register(char const*, unsigned char, unsigned char)'

libraries\RF24ArduinoCommunicator-master\RF24.cpp.o (symbol from plugin):(.text+0x0): first defined here

libraries\RF24-master\RF24.cpp.o (symbol from plugin): In function `RF24::csn(bool)':

(.text+0x0): multiple definition of `RF24::print_address_register(char const*, unsigned char, unsigned char)'

libraries\RF24ArduinoCommunicator-master\RF24.cpp.o (symbol from plugin):(.text+0x0): first defined here

libraries\RF24-master\RF24.cpp.o (symbol from plugin): In function `RF24::csn(bool)':

(.text+0x0): multiple definition of `RF24::RF24(unsigned char, unsigned char)'

libraries\RF24ArduinoCommunicator-master\RF24.cpp.o (symbol from plugin):(.text+0x0): first defined here

libraries\RF24-master\RF24.cpp.o (symbol from plugin): In function `RF24::csn(bool)':

(.text+0x0): multiple definition of `RF24::RF24(unsigned char, unsigned char)'

libraries\RF24ArduinoCommunicator-master\RF24.cpp.o (symbol from plugin):(.text+0x0): first defined here

libraries\RF24-master\RF24.cpp.o (symbol from plugin): In function `RF24::csn(bool)':

(.text+0x0): multiple definition of `RF24::setChannel(unsigned char)'

libraries\RF24ArduinoCommunicator-master\RF24.cpp.o (symbol from plugin):(.text+0x0): first defined here

libraries\RF24-master\RF24.cpp.o (symbol from plugin): In function `RF24::csn(bool)':

(.text+0x0): multiple definition of `RF24::setPayloadSize(unsigned char)'

libraries\RF24ArduinoCommunicator-master\RF24.cpp.o (symbol from plugin):(.text+0x0): first defined here

libraries\RF24-master\RF24.cpp.o (symbol from plugin): In function `RF24::csn(bool)':

(.text+0x0): multiple definition of `RF24::getPayloadSize()'

libraries\RF24ArduinoCommunicator-master\RF24.cpp.o (symbol from plugin):(.text+0x0): first defined here

libraries\RF24-master\RF24.cpp.o (symbol from plugin): In function `RF24::csn(bool)':

(.text+0x0): multiple definition of `RF24::stopListening()'

libraries\RF24ArduinoCommunicator-master\RF24.cpp.o (symbol from plugin):(.text+0x0): first defined here

libraries\RF24-master\RF24.cpp.o (symbol from plugin): In function `RF24::csn(bool)':

(.text+0x0): multiple definition of `RF24::powerDown()'

libraries\RF24ArduinoCommunicator-master\RF24.cpp.o (symbol from plugin):(.text+0x0): first defined here

libraries\RF24-master\RF24.cpp.o (symbol from plugin): In function `RF24::csn(bool)':

(.text+0x0): multiple definition of `RF24::powerUp()'

libraries\RF24ArduinoCommunicator-master\RF24.cpp.o (symbol from plugin):(.text+0x0): first defined here

libraries\RF24-master\RF24.cpp.o (symbol from plugin): In function `RF24::csn(bool)':

(.text+0x0): multiple definition of `RF24::write(void const*, unsigned char)'

libraries\RF24ArduinoCommunicator-master\RF24.cpp.o (symbol from plugin):(.text+0x0): first defined here

libraries\RF24-master\RF24.cpp.o (symbol from plugin): In function `RF24::csn(bool)':

(.text+0x0): multiple definition of `RF24::available()'

libraries\RF24ArduinoCommunicator-master\RF24.cpp.o (symbol from plugin):(.text+0x0): first defined here

libraries\RF24-master\RF24.cpp.o (symbol from plugin): In function `RF24::csn(bool)':

(.text+0x0): multiple definition of `RF24::read(void*, unsigned char)'

libraries\RF24ArduinoCommunicator-master\RF24.cpp.o (symbol from plugin):(.text+0x0): first defined here

libraries\RF24-master\RF24.cpp.o (symbol from plugin): In function `RF24::csn(bool)':

(.text+0x0): multiple definition of `RF24::whatHappened(bool&amp;, bool&amp;, bool&amp;)'

libraries\RF24ArduinoCommunicator-master\RF24.cpp.o (symbol from plugin):(.text+0x0): first defined here

libraries\RF24-master\RF24.cpp.o (symbol from plugin): In function `RF24::csn(bool)':

(.text+0x0): multiple definition of `RF24::openWritingPipe(unsigned long long)'

libraries\RF24ArduinoCommunicator-master\RF24.cpp.o (symbol from plugin):(.text+0x0): first defined here

libraries\RF24-master\RF24.cpp.o (symbol from plugin): In function `RF24::csn(bool)':

(.text+0x0): multiple definition of `RF24::startListening()'

libraries\RF24ArduinoCommunicator-master\RF24.cpp.o (symbol from plugin):(.text+0x0): first defined here

libraries\RF24-master\RF24.cpp.o (symbol from plugin): In function `RF24::csn(bool)':

(.text+0x0): multiple definition of `RF24::toggle_features()'

libraries\RF24ArduinoCommunicator-master\RF24.cpp.o (symbol from plugin):(.text+0x0): first defined here

libraries\RF24-master\RF24.cpp.o (symbol from plugin): In function `RF24::csn(bool)':

(.text+0x0): multiple definition of `RF24::enableDynamicPayloads()'

libraries\RF24ArduinoCommunicator-master\RF24.cpp.o (symbol from plugin):(.text+0x0): first defined here

libraries\RF24-master\RF24.cpp.o (symbol from plugin): In function `RF24::csn(bool)':

(.text+0x0): multiple definition of `RF24::enableAckPayload()'

libraries\RF24ArduinoCommunicator-master\RF24.cpp.o (symbol from plugin):(.text+0x0): first defined here

libraries\RF24-master\RF24.cpp.o (symbol from plugin): In function `RF24::csn(bool)':

(.text+0x0): multiple definition of `RF24::writeAckPayload(unsigned char, void const*, unsigned char)'

libraries\RF24ArduinoCommunicator-master\RF24.cpp.o (symbol from plugin):(.text+0x0): first defined here

libraries\RF24-master\RF24.cpp.o (symbol from plugin): In function `RF24::csn(bool)':

(.text+0x0): multiple definition of `RF24::isAckPayloadAvailable()'

libraries\RF24ArduinoCommunicator-master\RF24.cpp.o (symbol from plugin):(.text+0x0): first defined here

libraries\RF24-master\RF24.cpp.o (symbol from plugin): In function `RF24::csn(bool)':

(.text+0x0): multiple definition of `RF24::isPVariant()'

libraries\RF24ArduinoCommunicator-master\RF24.cpp.o (symbol from plugin):(.text+0x0): first defined here

libraries\RF24-master\RF24.cpp.o (symbol from plugin): In function `RF24::csn(bool)':

(.text+0x0): multiple definition of `RF24::testCarrier()'

libraries\RF24ArduinoCommunicator-master\RF24.cpp.o (symbol from plugin):(.text+0x0): first defined here

libraries\RF24-master\RF24.cpp.o (symbol from plugin): In function `RF24::csn(bool)':

(.text+0x0): multiple definition of `RF24::testRPD()'

libraries\RF24ArduinoCommunicator-master\RF24.cpp.o (symbol from plugin):(.text+0x0): first defined here

libraries\RF24-master\RF24.cpp.o (symbol from plugin): In function `RF24::csn(bool)':

(.text+0x0): multiple definition of `RF24::getPALevel()'

libraries\RF24ArduinoCommunicator-master\RF24.cpp.o (symbol from plugin):(.text+0x0): first defined here

libraries\RF24-master\RF24.cpp.o (symbol from plugin): In function `RF24::csn(bool)':

(.text+0x0): multiple definition of `RF24::setDataRate(rf24_datarate_e)'

libraries\RF24ArduinoCommunicator-master\RF24.cpp.o (symbol from plugin):(.text+0x0): first defined here

libraries\RF24-master\RF24.cpp.o (symbol from plugin): In function `RF24::csn(bool)':

(.text+0x0): multiple definition of `RF24::getDataRate()'

libraries\RF24ArduinoCommunicator-master\RF24.cpp.o (symbol from plugin):(.text+0x0): first defined here

libraries\RF24-master\RF24.cpp.o (symbol from plugin): In function `RF24::csn(bool)':

(.text+0x0): multiple definition of `RF24::setCRCLength(rf24_crclength_e)'

libraries\RF24ArduinoCommunicator-master\RF24.cpp.o (symbol from plugin):(.text+0x0): first defined here

libraries\RF24-master\RF24.cpp.o (symbol from plugin): In function `RF24::csn(bool)':

(.text+0x0): multiple definition of `RF24::getCRCLength()'

libraries\RF24ArduinoCommunicator-master\RF24.cpp.o (symbol from plugin):(.text+0x0): first defined here

libraries\RF24-master\RF24.cpp.o (symbol from plugin): In function `RF24::csn(bool)':

(.text+0x0): multiple definition of `RF24::printDetails()'

libraries\RF24ArduinoCommunicator-master\RF24.cpp.o (symbol from plugin):(.text+0x0): first defined here

libraries\RF24-master\RF24.cpp.o (symbol from plugin): In function `RF24::csn(bool)':

(.text+0x0): multiple definition of `RF24::disableCRC()'

libraries\RF24ArduinoCommunicator-master\RF24.cpp.o (symbol from plugin):(.text+0x0): first defined here

libraries\RF24-master\RF24.cpp.o (symbol from plugin): In function `RF24::csn(bool)':

(.text+0x0): multiple definition of `RF24::setRetries(unsigned char, unsigned char)'

libraries\RF24ArduinoCommunicator-master\RF24.cpp.o (symbol from plugin):(.text+0x0): first defined here

libraries\RF24-master\RF24.cpp.o (symbol from plugin): In function `RF24::csn(bool)':

(.text+0x0): multiple definition of `RF24::begin()'

libraries\RF24ArduinoCommunicator-master\RF24.cpp.o (symbol from plugin):(.text+0x0): first defined here

collect2.exe: error: ld returned 1 exit status

Multiple libraries were found for "nRF24L01.h"
 Used: C:\Users\Owner\Documents\Arduino\libraries\RF24ArduinoCommunicator-master
 Not used: C:\Users\Owner\Documents\Arduino\libraries\RF24-master
 Not used: C:\Users\Owner\Documents\Arduino\libraries\RF24-master
 Not used: C:\Users\Owner\Documents\Arduino\libraries\RF24-master
 Not used: C:\Users\Owner\Documents\Arduino\libraries\RF24-master
exit status 1
Error compiling for board Arduino/Genuino Uno.

This report would have more information with
"Show verbose output during compilation"
option enabled in File -&gt; Preferences.
</code></pre>

<p>Example I tried to compile:</p>

<pre><code>/*
 Copyright (C) 2011 J. Coliz &lt;maniacbug@ymail.com&gt;

 This program is free software; you can redistribute it and/or
 modify it under the terms of the GNU General Public License
 version 2 as published by the Free Software Foundation.
 */

#include &lt;SPI.h&gt;
#include "nRF24L01.h"
#include "RF24.h"
#include "printf.h"

//
// Hardware configuration
//

// Set up nRF24L01 radio on SPI bus plus pins 9 &amp; 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(void)
{
  //
  // Print preamble
  //

  Serial.begin(57600);
  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();

  // optionally, increase the delay between retries &amp; # 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();
}

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

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

    // Take the time, and send it.  This will block until complete
    unsigned long time = millis();
    printf("Now sending %lu...",time);
    bool ok = radio.write( &amp;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() &amp;&amp; ! timeout )
      if (millis() - started_waiting_at &gt; 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( &amp;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( &amp;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( &amp;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' &amp;&amp; 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' &amp;&amp; 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]);
    }
  }
}
</code></pre>
 11529: <p>You have multiple copies of the library.</p>

<p>Delete the folder located at:</p>

<pre><code>C:\Users\Owner\Documents\Arduino\libraries\RF24ArduinoCommunicator-master
</code></pre>
