text: /*
   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.
  
   03/17/2013 : Charles-Henri Hallard (http://hallard.me)
                Modified to use with Arduipi board http://hallard.me/arduipi
  						  Changed to use modified bcm2835 and RF24 library
  TMRh20 2014 - Updated to work with optimized RF24 Arduino library
  
   */
  
  /**
   * Example RF Radio Ping Pair
   *
   * This is an example of how to use the RF24 class on RPi, communicating to an Arduino running
   * the GettingStarted sketch.
   */
  
  #include <cstdlib>
  #include <iostream>
  #include <sstream>
  #include <string>
  #include <unistd.h>
  #include <RF24/RF24.h>
  
  using namespace std;
  //
  // Hardware configuration
  // Configure the appropriate pins for your connections
  
  /****************** Raspberry Pi ***********************/
  
  // Radio CE Pin, CSN Pin, SPI Speed
  // See http://www.airspayce.com/mikem/bcm2835/group__constants.html#ga63c029bd6500167152db4e57736d0939 and the related enumerations for pin information.
  
  // Setup for GPIO 22 CE and CE0 CSN with SPI Speed @ 4Mhz
  //RF24 radio(RPI_V2_GPIO_P1_22, BCM2835_SPI_CS0, BCM2835_SPI_SPEED_4MHZ);
  
  // NEW: Setup for RPi B+
  //RF24 radio(RPI_BPLUS_GPIO_J8_15,RPI_BPLUS_GPIO_J8_24, BCM2835_SPI_SPEED_8MHZ);
  
  // Setup for GPIO 15 CE and CE0 CSN with SPI Speed @ 8Mhz
  //RF24 radio(RPI_V2_GPIO_P1_15, RPI_V2_GPIO_P1_24, BCM2835_SPI_SPEED_8MHZ);
  
  // RPi generic:
  RF24 radio(22,0);
  
  /*** RPi Alternate ***/
  //Note: Specify SPI BUS 0 or 1 instead of CS pin number.
  // See http://tmrh20.github.io/RF24/RPi.html for more information on usage
  
  //RPi Alternate, with MRAA
  //RF24 radio(15,0);
  
  //RPi Alternate, with SPIDEV - Note: Edit RF24/arch/BBB/spi.cpp and  set 'this->device = "/dev/spidev0.0";;' or as listed in /dev
  //RF24 radio(22,0);
  
  
  /****************** Linux (BBB,x86,etc) ***********************/
  
  // See http://tmrh20.github.io/RF24/pages.html for more information on usage
  // See http://iotdk.intel.com/docs/master/mraa/ for more information on MRAA
  // See https://www.kernel.org/doc/Documentation/spi/spidev for more information on SPIDEV
  
  // Setup for ARM(Linux) devices like BBB using spidev (default is "/dev/spidev1.0" )
  //RF24 radio(115,0);
  
  //BBB Alternate, with mraa
  // CE pin = (Header P9, Pin 13) = 59 = 13 + 46 
  //Note: Specify SPI BUS 0 or 1 instead of CS pin number. 
  //RF24 radio(59,0);
  
  /********** User Config *********/
  // Assign a unique identifier for this node, 0 or 1
  bool radioNumber = 1;
  
  /********************************/
  
  // Radio pipe addresses for the 2 nodes to communicate.
  const uint8_t pipes[][6] = {"1Node","2Node"};
  
  
  int main(int argc, char** argv){
  
    bool role_ping_out = true, role_pong_back = false;
    bool role = role_pong_back;
  
    cout << "RF24/examples/GettingStarted/\n";
  
    // Setup and configure rf radio
    radio.begin();
  
    // optionally, increase the delay between retries & # of retries
    radio.setRetries(15,15);
    // Dump the configuration of the rf unit for debugging
    radio.printDetails();
  
  
  /********* Role chooser ***********/
  
    printf("\n ************ Role Setup ***********\n");
    string input = "";
    char myChar = {0};
    cout << "Choose a role: Enter 0 for pong_back, 1 for ping_out (CTRL+C to exit) \n>";
    getline(cin,input);
  
    if(input.length() == 1) {
  	myChar = input[0];
  	if(myChar == '0'){
  		cout << "Role: Pong Back, awaiting transmission " << endl << endl;
  	}else{  cout << "Role: Ping Out, starting transmission " << endl << endl;
  		role = role_ping_out;
  	}
    }
  /***********************************/
    // This simple sketch opens two pipes for these two nodes to communicate
    // back and forth.
  
      if ( !radioNumber )    {
        radio.openWritingPipe(pipes[0]);
        radio.openReadingPipe(1,pipes[1]);
      } else {
        radio.openWritingPipe(pipes[1]);
        radio.openReadingPipe(1,pipes[0]);
      }
  	
  	radio.startListening();
  	
  	// forever loop
  	while (1)
  	{
  		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
  
  			printf("Now sending...\n");
  			unsigned long time = millis();
  
  			bool ok = radio.write( &time, sizeof(unsigned long) );
  
  			if (!ok){
  				printf("failed.\n");
  			}
  			// 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");
  			}
  			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",got_time,millis()-got_time);
  			}
  			sleep(1);
  		}
  
  		//
  		// 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;
  
  				// Fetch the payload, and see if this was the last one.
  				while(radio.available()){
  					radio.read( &got_time, sizeof(unsigned long) );
  				}
  				radio.stopListening();
  				
  				radio.write( &got_time, sizeof(unsigned long) );
  
  				// Now, resume listening so we catch the next packets.
  				radio.startListening();
  
  				// Spew it
  				printf("Got payload(%d) %lu...\n",sizeof(unsigned long), got_time);
  				
  				delay(925); //Delay after payload responded to, minimize RPi CPU time
  				
  			}
  		
  		}
  
  	} // forever loop
  
    return 0;
  }
  
  