Raspberry Pi support

Added support for hardware SPI on RPI per jscrane fork:
- Fixed a few bugs with single SPI transfers
- Aligned with optimized RF24 library fork
- Updated bmc2835 files per
http://www.airspayce.com/mikem/bcm2835/index.html
- Merged bcm files with changes from
https://github.com/farconada/RF24Network
- Added example files
- Added setup info to readme

RPi/RF24/Makefile

+#############################################################################
+#
+# Makefile for librf24-bcm on Raspberry Pi
+#
+# License: GPL (General Public License)
+# Author:  Charles-Henri Hallard 
+# Date:    2013/03/13 
+#
+# Description:
+# ------------
+# use make all and mak install to install the library 
+# You can change the install directory by editing the LIBDIR line
+#
+PREFIX=/usr/local
+
+# Library parameters
+# where to put the lib
+LIBDIR=$(PREFIX)/lib
+# lib name 
+LIB=librf24-bcm
+# shared library name
+LIBNAME=$(LIB).so.1.0
+
+
+# The recommended compiler flags for the Raspberry Pi
+CCFLAGS=-Ofast -mfpu=vfp -mfloat-abi=hard -march=armv6zk -mtune=arm1176jzf-s
+
+# make all
+# reinstall the library after each recompilation
+all: librf24-bcm install
+
+# Make the library
+librf24-bcm: RF24.o bcm2835.o 
+	g++ -shared -Wl,-soname,$@.so.1 ${CCFLAGS} -o ${LIBNAME} $^
+	
+# Library parts
+RF24.o: RF24.cpp
+	g++ -Wall -fPIC ${CCFLAGS} -c $^
+
+bcm2835.o: bcm2835.c
+	gcc -Wall -fPIC ${CCFLAGS} -c $^
+
+# clear build files
+clean:
+	rm -rf *.o ${LIB}.*
+
+# Install the library to LIBPATH
+install: 
+	@echo "[Install]"
+	@if ( test ! -d $(PREFIX)/lib ) ; then mkdir -p $(PREFIX)/lib ; fi
+	#@install -m 0755 ${LIB}.a ${LIBDIR}
+	@install -m 0755 ${LIBNAME} ${LIBDIR}
+	@ln -sf ${LIBDIR}/${LIBNAME} ${LIBDIR}/${LIB}.so.1
+	@ln -sf ${LIBDIR}/${LIBNAME} ${LIBDIR}/${LIB}.so
+	@ldconfig

RPi/RF24/RF24_config.h

+
+/*
+ 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
+              Modified to use the great bcm2835 library for I/O and SPI
+							
+ */
+
+#ifndef __RF24_CONFIG_H__
+#define __RF24_CONFIG_H__
+
+#include <stdint.h>
+#include <stdio.h>
+#include <time.h>
+#include <string.h>
+#include <sys/time.h>
+#include <stddef.h>
+#include "bcm2835.h"
+
+// GCC a Arduino Missing
+#define max(a,b) (a>b?a:b)
+#define min(a,b) (a<b?a:b)
+#define _BV(x) (1<<(x))
+#define pgm_read_word(p) (*(p))
+#define pgm_read_byte(p) (*(p))
+
+#endif // __RF24_CONFIG_H__
+// vim:ai:cin:sts=2 sw=2 ft=cpp

RPi/RF24/examples/Makefile

+#############################################################################
+#
+# Makefile for librf24 examples on Raspberry Pi
+#
+# License: GPL (General Public License)
+# Author:  gnulnulf <arco@appeltaart.mine.nu>
+# Date:    2013/02/07 (version 1.0)
+#
+# Description:
+# ------------
+# use make all and make install to install the examples
+# You can change the install directory by editing the prefix line
+#
+prefix := /usr/local
+
+# The recommended compiler flags for the Raspberry Pi
+CCFLAGS=-Ofast -mfpu=vfp -mfloat-abi=hard -march=armv6zk -mtune=arm1176jzf-s
+#CCFLAGS=
+
+# define all programs
+#PROGRAMS = scanner pingtest gettingstarted
+PROGRAMS = gettingstarted gettingstarted_call_response transfer pingpair_dyn
+SOURCES = ${PROGRAMS:=.cpp}
+
+all: ${PROGRAMS}
+
+${PROGRAMS}: ${SOURCES}
+	g++ ${CCFLAGS} -Wall -I../ -lrf24-bcm $@.cpp -o $@
+
+clean:
+	rm -rf $(PROGRAMS)
+
+install: all
+	test -d $(prefix) || mkdir $(prefix)
+	test -d $(prefix)/bin || mkdir $(prefix)/bin
+	for prog in $(PROGRAMS); do \
+	  install -m 0755 $$prog $(prefix)/bin; \
+	done
+
+.PHONY: install

RPi/RF24/examples/extra/Makefile

+#############################################################################
+#
+# Makefile for librf24 examples on Raspberry Pi
+#
+# License: GPL (General Public License)
+# Author:  gnulnulf <arco@appeltaart.mine.nu>
+# Date:    2013/02/07 (version 1.0)
+#
+# Description:
+# ------------
+# use make all and make install to install the examples
+# You can change the install directory by editing the prefix line
+#
+prefix := /usr/local
+
+# The recommended compiler flags for the Raspberry Pi
+CCFLAGS=-Ofast -mfpu=vfp -mfloat-abi=hard -march=armv6zk -mtune=arm1176jzf-s
+#CCFLAGS=
+
+# define all programs
+PROGRAMS = rpi-hub scanner
+
+SOURCES = ${PROGRAMS:=.cpp}
+
+all: ${PROGRAMS}
+
+${PROGRAMS}: ${SOURCES}
+	g++ ${CCFLAGS} -Wall -I../ -lrf24-bcm $@.cpp -o $@
+
+clean:
+	rm -rf $(PROGRAMS)
+
+install: all
+	test -d $(prefix) || mkdir $(prefix)
+	test -d $(prefix)/bin || mkdir $(prefix)/bin
+	for prog in $(PROGRAMS); do \
+	  install -m 0755 $$prog $(prefix)/bin; \
+	done
+
+.PHONY: install

RPi/RF24/examples/extra/rpi-hub.cpp

+/* 
+ *
+ *  Filename : rpi-hub.cpp
+ *
+ *  This program makes the RPi as a hub listening to all six pipes from the remote sensor nodes ( usually Arduino )
+ *  and will return the packet back to the sensor on pipe0 so that the sender can calculate the round trip delays
+ *  when the payload matches.
+ *  
+ *  I encounter that at times, it also receive from pipe7 ( or pipe0 ) with content of FFFFFFFFF that I will not sent
+ *  back to the sender
+ *
+ *  Refer to RF24/examples/rpi_hub_arduino/ for the corresponding Arduino sketches to work with this code.
+ * 
+ *  
+ *  CE is not used and CSN is GPIO25 (not pinout)
+ *
+ *  Refer to RPi docs for GPIO numbers
+ *
+ *  Author : Stanley Seow
+ *  e-mail : stanleyseow@gmail.com
+ *  date   : 6th Mar 2013
+ *
+ * 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 
+ *
+ *
+ */
+
+#include <cstdlib>
+#include <iostream>
+#include "../RF24.h"
+
+using namespace std;
+
+// Radio pipe addresses for the 2 nodes to communicate.
+// First pipe is for writing, 2nd, 3rd, 4th, 5th & 6th is for reading...
+const uint64_t pipes[6] = 
+					{ 0xF0F0F0F0D2LL, 0xF0F0F0F0E1LL, 
+						0xF0F0F0F0E2LL, 0xF0F0F0F0E3LL, 
+						0xF0F0F0F0F1, 0xF0F0F0F0F2 
+					};
+
+// CE Pin, CSN Pin, SPI Speed
+
+// Setup for GPIO 22 CE and GPIO 25 CSN with SPI Speed @ 1Mhz
+//RF24 radio(RPI_V2_GPIO_P1_22, RPI_V2_GPIO_P1_18, BCM2835_SPI_SPEED_1MHZ);
+
+// Setup for GPIO 22 CE and CE0 CSN with SPI Speed @ 4Mhz
+//RF24 radio(RPI_V2_GPIO_P1_15, BCM2835_SPI_CS0, BCM2835_SPI_SPEED_4MHZ); 
+
+// Setup for GPIO 22 CE and CE1 CSN with SPI Speed @ 8Mhz
+RF24 radio(RPI_V2_GPIO_P1_15, RPI_V2_GPIO_P1_26, BCM2835_SPI_SPEED_8MHZ);  
+
+
+int main(int argc, char** argv) 
+{
+	uint8_t len;
+
+	// Refer to RF24.h or nRF24L01 DS for settings
+	radio.begin();
+	radio.enableDynamicPayloads();
+	radio.setAutoAck(1);
+	radio.setRetries(15,15);
+	radio.setDataRate(RF24_1MBPS);
+	radio.setPALevel(RF24_PA_MAX);
+	radio.setChannel(76);
+	radio.setCRCLength(RF24_CRC_16);
+
+	// Open 6 pipes for readings ( 5 plus pipe0, also can be used for reading )
+	radio.openWritingPipe(pipes[0]);
+	radio.openReadingPipe(1,pipes[1]);
+	radio.openReadingPipe(2,pipes[2]);
+	radio.openReadingPipe(3,pipes[3]);
+	radio.openReadingPipe(4,pipes[4]);
+	radio.openReadingPipe(5,pipes[5]);
+
+	//
+	// Start listening
+	//
+	radio.startListening();
+
+	//
+	// Dump the configuration of the rf unit for debugging
+	//
+	radio.printDetails();
+	
+	printf("Output below : \n");
+	delay(1);
+	
+	while(1)
+	{
+		char receivePayload[32];
+		uint8_t pipe = 1;
+		
+		// Start listening
+		radio.startListening();
+					
+		while ( radio.available(&pipe) ) 
+		{
+			len = radio.getDynamicPayloadSize();
+			radio.read( receivePayload, len );
+
+			// Display it on screen
+			printf("Recv: size=%i payload=%s pipe=%i",len,receivePayload,pipe);
+
+			// Send back payload to sender
+			radio.stopListening();
+
+			// if pipe is 7, do not send it back
+			if ( pipe != 7 ) 
+			{
+				radio.write(receivePayload,len);
+				receivePayload[len]=0;
+				printf("\t Send: size=%i payload=%s pipe:%i\n",len,receivePayload,pipe);
+			}
+			else 
+			{
+				printf("\n");
+			}
+			
+			pipe++;
+			
+			// reset pipe to 0
+			if ( pipe > 6 ) 
+				pipe = 0;
+		}
+		
+		delayMicroseconds(20);
+	}
+	
+	return 0;
+}
+

RPi/RF24/examples/extra/scanner.cpp

+/*
+ 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 
+
+ */
+
+/**
+ * Channel scanner
+ *
+ * Example to detect interference on the various channels available.
+ * This is a good diagnostic tool to check whether you're picking a
+ * good channel for your application.
+ *
+ * Inspired by cpixip.
+ * See http://arduino.cc/forum/index.php/topic,54795.0.html
+ */
+
+#include <cstdlib>
+#include <iostream>
+#include "../RF24.h"
+
+using namespace std;
+
+//
+// Hardware configuration
+//
+
+// CE Pin, CSN Pin, SPI Speed
+
+// Setup for GPIO 22 CE and GPIO 25 CSN with SPI Speed @ 1Mhz
+//RF24 radio(RPI_V2_GPIO_P1_22, RPI_V2_GPIO_P1_18, BCM2835_SPI_SPEED_1MHZ);
+
+// Setup for GPIO 22 CE and CE0 CSN with SPI Speed @ 4Mhz
+//RF24 radio(RPI_V2_GPIO_P1_15, BCM2835_SPI_CS0, BCM2835_SPI_SPEED_4MHZ); 
+
+// Setup for GPIO 22 CE and CE1 CSN with SPI Speed @ 8Mhz
+RF24 radio(RPI_V2_GPIO_P1_15, RPI_V2_GPIO_P1_26, BCM2835_SPI_SPEED_8MHZ);  
+
+
+//
+// Channel info
+//
+//const uint8_t num_channels = 128;
+const uint8_t num_channels = 120;
+uint8_t values[num_channels];
+
+
+const int num_reps = 100;
+int reset_array=0;
+
+
+int main(int argc, char** argv)
+{
+  //
+  // Print preamble
+  //
+
+  //Serial.begin(57600);
+  //printf_begin();
+  printf("RF24/examples/scanner/\n");
+
+  //
+  // Setup and configure rf radio
+  //
+  radio.begin();
+	
+  radio.setAutoAck(false);
+
+  // Get into standby mode
+  radio.startListening();
+  radio.stopListening();
+
+  radio.printDetails();
+
+  // Print out header, high then low digit
+  int i = 0;
+	
+  while ( i < num_channels )
+  {
+    printf("%x",i>>4);
+    ++i;
+  }
+  printf("\n");
+	
+  i = 0;
+  while ( i < num_channels )
+  {
+    printf("%x",i&0xf);
+    ++i;
+  }
+  printf("\n");       
+	
+	// forever loop
+  while(1)
+	{
+		if ( reset_array == 1 )
+		{	
+			// Clear measurement values
+			memset(values,0,sizeof(values));
+			printf("\n");
+		}
+
+		// Scan all channels num_reps times
+		int i = num_channels;
+		while (i--)
+		{
+			// Select this channel
+			radio.setChannel(i);
+
+			// Listen for a little
+			radio.startListening();
+			delayMicroseconds(128);
+			//radio.stopListening();
+
+			// Did we get a carrier?
+			if ( radio.testCarrier() )
+					++values[i];
+			if ( values[i] == 0xf ) 
+			{
+				reset_array = 2;
+			}
+			radio.stopListening();
+		}
+
+		// Print out channel measurements, clamped to a single hex digit
+		i = 0;
+		while ( i < num_channels )
+		{
+			printf("%x",min(0xf,(values[i]&0xf)));
+			++i;
+		}
+		
+		printf("\n");
+	}
+	
+  return 0;
+}
+
+// vim:ai:cin:sts=2 sw=2 ft=cpp

RPi/RF24/examples/gettingstarted.cpp

+/*
+ 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 "./RF24.h"
+
+using namespace std;
+//
+// Hardware configuration
+//
+
+// CE Pin, CSN Pin, SPI Speed
+
+// Setup for GPIO 22 CE and GPIO 25 CSN with SPI Speed @ 1Mhz
+//RF24 radio(RPI_V2_GPIO_P1_22, RPI_V2_GPIO_P1_18, BCM2835_SPI_SPEED_1MHZ);
+
+// Setup for GPIO 22 CE and CE0 CSN with SPI Speed @ 4Mhz
+//RF24 radio(RPI_V2_GPIO_P1_15, BCM2835_SPI_CS0, BCM2835_SPI_SPEED_4MHZ);
+
+// Setup for GPIO 22 CE and CE1 CSN with SPI Speed @ 8Mhz
+//RF24 radio(RPI_V2_GPIO_P1_15, RPI_V2_GPIO_P1_26, BCM2835_SPI_SPEED_8MHZ);
+RF24 radio(RPI_V2_GPIO_P1_15,BCM2835_SPI_CS0, BCM2835_SPI_SPEED_8MHZ);
+
+
+
+// Radio pipe addresses for the 2 nodes to communicate.
+const uint64_t pipes[2] = { 0xABCDABCD71LL, 0x544d52687CLL };
+
+bool role_ping_out = 1, role_pong_back = 0;
+bool role = 0;
+
+int main(int argc, char** argv){
+
+
+  // Print preamble:
+  printf("RF24/examples/pingtest/\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 ( role == role_ping_out )    {
+      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 ) {
+					// by bcatalin » Thu Feb 14, 2013 11:26 am
+					//delay(5); //add a small delay to let radio.available to check payload
+				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);
+			}
+
+			// Try again 1s later
+			//    delay(1000);
+			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
+			//printf("Check available...\n");
+			//delay(3);
+			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.
+				radio.read( &got_time, sizeof(unsigned long) );
+
+				radio.stopListening();
+				//delay(1);
+				// Seem to need a  delay, or the RPi is too quick
+				radio.write( &got_time, sizeof(unsigned long) );
+
+				//delay(1);
+				// Now, resume listening so we catch the next packets.
+				radio.startListening();
+				 //delay(1);
+				// Spew it
+				printf("Got payload(%d) %lu...\n",sizeof(unsigned long), got_time);
+			}
+		//delay(5);
+		}
+	} // forever loop
+
+  return 0;
+}
+

RPi/RF24/examples/gettingstarted_call_response.cpp

+/*
+TMRh20 2014 - Updated to work with optimized RF24 Arduino library
+*/
+
+
+/**
+ * Example for efficient call-response using ack-payloads
+ *
+ * This example continues to make use of all the normal functionality of the radios including
+ * the auto-ack and auto-retry features, but allows ack-payloads to be written optionlly as well.
+ * This allows very fast call-response communication, with the responding radio never having to
+ * switch out of Primary Receiver mode to send back a payload, but having the option to switch to
+ * primary transmitter if wanting to initiate communication instead of respond to a commmunication.
+ */
+
+#include <cstdlib>
+#include <iostream>
+#include <sstream>
+#include <string>
+#include "./RF24.h"
+
+using namespace std;
+
+//
+// Hardware configuration
+//
+
+// CE Pin, CSN Pin, SPI Speed
+
+// Setup for GPIO 22 CE and GPIO 25 CSN with SPI Speed @ 1Mhz
+//RF24 radio(RPI_V2_GPIO_P1_22, RPI_V2_GPIO_P1_18, BCM2835_SPI_SPEED_1MHZ);
+
+// Setup for GPIO 22 CE and CE0 CSN with SPI Speed @ 4Mhz
+//RF24 radio(RPI_V2_GPIO_P1_15, BCM2835_SPI_CS0, BCM2835_SPI_SPEED_4MHZ);
+
+// Setup for GPIO 22 CE and CE1 CSN with SPI Speed @ 8Mhz
+RF24 radio(RPI_V2_GPIO_P1_15, BCM2835_SPI_CS0, BCM2835_SPI_SPEED_8MHZ);
+
+
+
+// Radio pipe addresses for the 2 nodes to communicate.
+const uint64_t addresses[2] = { 0xABCDABCD71LL, 0x544d52687CLL };
+
+bool role_ping_out = 1, role_pong_back = 0, role = 0;
+
+uint8_t counter = 1;                                                          // A single byte to keep track of the data being sent back and forth
+
+
+int main(int argc, char** argv){
+
+
+  printf("RF24/examples/gettingstarted_call_response\n");
+
+  radio.begin();
+  radio.setAutoAck(1);                    // Ensure autoACK is enabled
+  radio.enableAckPayload();               // Allow optional ack payloads
+  radio.setRetries(1,15);                 // Smallest time between retries, max no. of retries
+  radio.setPayloadSize(1);                // Here we are sending 1-byte payloads to test the call-response speed
+  //radio.powerUp();
+  radio.printDetails();                   // Dump the configuration of the rf unit for debugging
+
+
+/********* 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 ( role == role_ping_out )    {
+      radio.openWritingPipe(addresses[0]);
+      radio.openReadingPipe(1,addresses[1]);
+    }else{
+      radio.openWritingPipe(addresses[1]);
+      radio.openReadingPipe(1,addresses[0]);
+      radio.startListening();
+    }
+
+// forever loop
+while (1){
+
+
+/****************** Ping Out Role ***************************/
+
+  if (role == role_ping_out){                               // Radio is in ping mode
+
+    uint8_t gotByte;                                           // Initialize a variable for the incoming response
+
+    radio.stopListening();                                  // First, stop listening so we can talk.
+    printf("Now sending %d as payload. ",counter);          // Use a simple byte counter as payload
+    unsigned long time = millis();                          // Record the current microsecond count
+
+    if ( radio.write(&counter,1) ){                         // Send the counter variable to the other radio
+        if(!radio.available()){                             // If nothing in the buffer, we got an ack but it is blank
+            printf("Got blank response. round-trip delay: %lu ms\n\r",millis()-time);
+        }else{
+            while(radio.available() ){                      // If an ack with payload was received
+                radio.read( &gotByte, 1 );                  // Read it, and display the response time
+                printf("Got response %d, round-trip delay: %lu ms\n\r",gotByte,millis()-time);
+                counter++;                                  // Increment the counter variable
+            }
+        }
+
+    }else{        printf("Sending failed.\n\r"); }          // If no ack response, sending failed
+
+    sleep(1);  // Try again later
+  }
+
+/****************** Pong Back Role ***************************/
+
+  if ( role == role_pong_back ) {
+    uint8_t pipeNo, gotByte;                       // Declare variables for the pipe and the byte received
+    while( radio.available(&pipeNo)){              // Read all available payloads
+      radio.read( &gotByte, 1 );
+                                                   // Since this is a call-response. Respond directly with an ack payload.
+      		  				                       // Ack payloads are much more efficient than switching to transmit mode to respond to a call
+      radio.writeAckPayload(pipeNo,&gotByte, 1 );  // This can be commented out to send empty payloads.
+      printf("Sent response %d \n\r", gotByte);
+   }
+ }
+
+} //while 1
+} //main
+
+

RPi/RF24/examples/pingpair_dyn.cpp

+/*
+	TMRh20 2014 - Optimized RF24 Library Fork
+*/
+
+/**
+ * Example using Dynamic Payloads 
+ *
+ * This is an example of how to use payloads of a varying (dynamic) size. 
+ */
+
+#include <cstdlib>
+#include <iostream>
+#include <sstream>
+#include <string>
+#include "./RF24.h"
+
+
+using namespace std;
+//
+// Hardware configuration
+//
+
+// CE Pin, CSN Pin, SPI Speed
+
+// Setup for GPIO 22 CE and GPIO 25 CSN with SPI Speed @ 1Mhz
+//RF24 radio(RPI_V2_GPIO_P1_22, RPI_V2_GPIO_P1_18, BCM2835_SPI_SPEED_1MHZ);
+
+// Setup for GPIO 22 CE and CE0 CSN with SPI Speed @ 4Mhz
+//RF24 radio(RPI_V2_GPIO_P1_15, BCM2835_SPI_CS0, BCM2835_SPI_SPEED_4MHZ); 
+
+// Setup for GPIO 22 CE and CE1 CSN with SPI Speed @ 8Mhz
+RF24 radio(RPI_V2_GPIO_P1_15, RPI_V2_GPIO_P1_26, BCM2835_SPI_SPEED_8MHZ);  
+
+
+// Radio pipe addresses for the 2 nodes to communicate.
+const uint64_t pipes[2] = { 0xF0F0F0F0E1LL, 0xF0F0F0F0D2LL };
+
+bool role_ping_out = 1, role_pong_back = 0;
+bool role = 0;
+
+const int min_payload_size = 4;
+const int max_payload_size = 32;
+const int payload_size_increments_by = 1;
+int next_payload_size = min_payload_size;
+
+char receive_payload[max_payload_size+1]; // +1 to allow room for a terminating NULL char
+
+int main(int argc, char** argv){
+
+ 
+  // Print preamble:
+  printf("RF24/examples/pingpair_dyn/\n");
+
+  // Setup and configure rf radio
+  radio.begin();
+  radio.enableDynamicPayloads();
+  radio.setRetries(5,15);
+  radio.printDetails();
+
+
+/********* Role chooser ***********/
+
+  printf("\n ************ Role Setup ***********\n");
+  string input = "";
+  char myChar = {0};
+  cout << "Choose a role: Enter 0 for receiver, 1 for transmitter (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;
+	}
+  }
+/***********************************/
+
+    if ( role == role_ping_out )    {
+      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)
+  {
+    // The payload will always be the same, what will change is how much of it we send.
+    static char send_payload[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZ789012";
+
+    // First, stop listening so we can talk.
+    radio.stopListening();
+
+    // Take the time, and send it.  This will block until complete
+    printf("Now sending length %i...",next_payload_size);
+    radio.write( send_payload, next_payload_size );
+
+    // Now, continue listening
+    radio.startListening();
+
+    // Wait here until we get a response, or timeout
+    unsigned long started_waiting_at = millis();
+    bool timeout = false;
+    while ( ! radio.available() && ! timeout )
+      if (millis() - started_waiting_at > 500 )
+        timeout = true;
+
+    // Describe the results
+    if ( timeout )
+    {
+      printf("Failed, response timed out.\n\r");
+    }
+    else
+    {
+      // Grab the response, compare, and send to debugging spew
+      uint8_t len = radio.getDynamicPayloadSize();
+      radio.read( receive_payload, len );
+
+      // Put a zero at the end for easy printing
+      receive_payload[len] = 0;
+
+      // Spew it
+      printf("Got response size=%i value=%s\n\r",len,receive_payload);
+    }
+    
+    // Update size for next time.
+    next_payload_size += payload_size_increments_by;
+    if ( next_payload_size > max_payload_size )
+      next_payload_size = min_payload_size;
+
+    // Try again 1s later
+    delay(100);
+  }
+
+  //
+  // 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
+      uint8_t len;
+
+      while (radio.available())
+      {
+        // Fetch the payload, and see if this was the last one.
+	len = radio.getDynamicPayloadSize();
+	radio.read( receive_payload, len );
+
+	// Put a zero at the end for easy printing
+	receive_payload[len] = 0;
+
+	// Spew it
+	printf("Got payload size=%i value=%s\n\r",len,receive_payload);
+      }
+
+      // First, stop listening so we can talk
+      radio.stopListening();
+
+      // Send the final one back.
+      radio.write( receive_payload, len );
+      printf("Sent response.\n\r");
+
+      // Now, resume listening so we catch the next packets.
+      radio.startListening();
+    }
+  }
+}
+}
+
+

RPi/RF24/examples/transfer.cpp

+/*
+TMRh20 2014
+
+ 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.
+ */
+
+/** General Data Transfer Rate Test
+ * This example demonstrates basic data transfer functionality with the 
+ updated library. This example will display the transfer rates acheived using
+ the slower form of high-speed transfer using blocking-writes.
+ */
+
+#include <cstdlib>
+#include <iostream>
+#include <sstream>
+#include <string>
+#include "./RF24.h"
+
+
+using namespace std;
+//
+// Hardware configuration
+//
+
+// CE Pin, CSN Pin, SPI Speed
+
+// Setup for GPIO 22 CE and GPIO 25 CSN with SPI Speed @ 1Mhz
+//RF24 radio(RPI_V2_GPIO_P1_22, RPI_V2_GPIO_P1_18, BCM2835_SPI_SPEED_1MHZ);
+
+// Setup for GPIO 22 CE and CE0 CSN with SPI Speed @ 4Mhz
+//RF24 radio(RPI_V2_GPIO_P1_15, BCM2835_SPI_CS0, BCM2835_SPI_SPEED_4MHZ); 
+
+// Setup for GPIO 22 CE and CE1 CSN with SPI Speed @ 8Mhz
+RF24 radio(RPI_V2_GPIO_P1_15, RPI_V2_GPIO_P1_26, BCM2835_SPI_SPEED_8MHZ);  
+
+
+
+// Radio pipe addresses for the 2 nodes to communicate.
+const uint64_t addresses[2] = { 0xABCDABCD71LL, 0x544d52687CLL };
+
+bool role_ping_out = 1, role_pong_back = 0;
+bool role = 0;
+uint8_t data[32]; 
+unsigned long startTime, stopTime, counter, rxTimer=0; 
+
+int main(int argc, char** argv){
+
+ 
+  // Print preamble:
+
+  printf("RF24/examples/Transfer/\n");
+  
+  radio.begin();                           // Setup and configure rf radio
+  radio.setChannel(1);
+  radio.setPALevel(RF24_PA_MAX);
+  radio.setDataRate(RF24_2MBPS);
+  radio.setAutoAck(1);                     // Ensure autoACK is enabled
+  radio.setRetries(2,15);                   // Optionally, increase the delay between retries & # of retries
+  radio.setCRCLength(RF24_CRC_8);
+  radio.printDetails();
+/********* Role chooser ***********/
+
+  printf("\n ************ Role Setup ***********\n");
+  string input = "";
+  char myChar = {0};
+  cout << "Choose a role: Enter 0 for receiver, 1 for transmitter (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;
+	}
+  }
+/***********************************/
+
+    if ( role == role_ping_out )    {
+      radio.openWritingPipe(addresses[0]);
+      radio.openReadingPipe(1,addresses[1]);
+    } else {
+      radio.openWritingPipe(addresses[1]);
+      radio.openReadingPipe(1,addresses[0]);
+      radio.startListening();
+    }
+    
+     
+  for(int i=0; i<32; i++){
+     data[i] = rand() % 255;               //Load the buffer with random data
+  }
+
+    // forever loop
+    while (1){
+
+	if (role == role_ping_out){
+		sleep(2);
+		printf("Initiating Basic Data Transfer\n\r");
+
+		long int cycles = 10000; //Change this to a higher or lower number.
+
+		startTime = millis();
+
+		for(int i=0; i<cycles; i++){        //Loop through a number of cycles
+      			data[0] = i;                      //Change the first byte of the payload for identification
+      			if(!radio.writeFast(&data,32)){   //Write to the FIFO buffers        
+        			counter++;                      //Keep count of failed payloads
+      			}
+    		}
+		stopTime = millis();
+
+		if(!radio.txStandBy()){ counter+=3; }
+
+  		float numBytes = cycles*32;
+   		float rate = numBytes / (stopTime - startTime);
+    
+  		printf("Transfer complete at %.2f KB/s \n\r",rate);
+   		printf("%lu of %lu Packets Failed to Send\n\r",counter,cycles);
+  		counter = 0;   
+
+	}
+    
+
+if(role == role_pong_back){
+     while(radio.available()){       
+      radio.read(&data,32);
+      counter++;
+     }
+   if(millis() - rxTimer > 1000){
+     rxTimer = millis();
+     printf("Rate: ");
+     float numBytes = counter*32;
+     printf("%.2f KB/s \n\r",numBytes/1000);
+     printf("Payload Count: %lu \n\r", counter);
+     counter = 0;
+   }
+  }
+
+} // loop
+} // main
+
+
+
+
+
+

RPi/RF24/nRF24L01.h

+/*
+    Copyright (c) 2007 Stefan Engelke <mbox@stefanengelke.de>
+    Portions Copyright (C) 2011 Greg Copeland
+
+    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.
+*/
+
+/* Memory Map */
+#define CONFIG      0x00
+#define EN_AA       0x01
+#define EN_RXADDR   0x02
+#define SETUP_AW    0x03
+#define SETUP_RETR  0x04
+#define RF_CH       0x05
+#define RF_SETUP    0x06
+#define STATUS      0x07
+#define OBSERVE_TX  0x08
+#define CD          0x09
+#define RX_ADDR_P0  0x0A
+#define RX_ADDR_P1  0x0B
+#define RX_ADDR_P2  0x0C
+#define RX_ADDR_P3  0x0D
+#define RX_ADDR_P4  0x0E
+#define RX_ADDR_P5  0x0F
+#define TX_ADDR     0x10
+#define RX_PW_P0    0x11
+#define RX_PW_P1    0x12
+#define RX_PW_P2    0x13
+#define RX_PW_P3    0x14
+#define RX_PW_P4    0x15
+#define RX_PW_P5    0x16
+#define FIFO_STATUS 0x17
+#define DYNPD	    0x1C
+#define FEATURE	    0x1D
+
+/* Bit Mnemonics */
+#define MASK_RX_DR  6
+#define MASK_TX_DS  5
+#define MASK_MAX_RT 4
+#define EN_CRC      3
+#define CRCO        2
+#define PWR_UP      1
+#define PRIM_RX     0
+#define ENAA_P5     5
+#define ENAA_P4     4
+#define ENAA_P3     3
+#define ENAA_P2     2
+#define ENAA_P1     1
+#define ENAA_P0     0
+#define ERX_P5      5
+#define ERX_P4      4
+#define ERX_P3      3
+#define ERX_P2      2
+#define ERX_P1      1
+#define ERX_P0      0
+#define AW          0
+#define ARD         4
+#define ARC         0
+#define PLL_LOCK    4
+#define RF_DR       3
+#define RF_PWR      6
+#define RX_DR       6
+#define TX_DS       5
+#define MAX_RT      4
+#define RX_P_NO     1
+#define TX_FULL     0
+#define PLOS_CNT    4
+#define ARC_CNT     0
+#define TX_REUSE    6
+#define FIFO_FULL   5
+#define TX_EMPTY    4
+#define RX_FULL     1
+#define RX_EMPTY    0
+#define DPL_P5	    5
+#define DPL_P4	    4
+#define DPL_P3	    3
+#define DPL_P2	    2
+#define DPL_P1	    1
+#define DPL_P0	    0
+#define EN_DPL	    2
+#define EN_ACK_PAY  1
+#define EN_DYN_ACK  0
+
+/* Instruction Mnemonics */
+#define R_REGISTER    0x00
+#define W_REGISTER    0x20
+#define REGISTER_MASK 0x1F
+#define ACTIVATE      0x50
+#define R_RX_PL_WID   0x60
+#define R_RX_PAYLOAD  0x61
+#define W_TX_PAYLOAD  0xA0
+#define W_ACK_PAYLOAD 0xA8
+#define FLUSH_TX      0xE1
+#define FLUSH_RX      0xE2
+#define REUSE_TX_PL   0xE3
+#define NOP           0xFF
+
+/* Non-P omissions */
+#define LNA_HCURR   0
+
+/* P model memory Map */
+#define RPD         0x09
+#define W_TX_PAYLOAD_NO_ACK  0xB0
+
+/* P model bit Mnemonics */
+#define RF_DR_LOW   5
+#define RF_DR_HIGH  3
+#define RF_PWR_LOW  1
+#define RF_PWR_HIGH 2

RPi/RF24/readme.md

+  
+Optimized Raspberry Pi RF24 and RF24 Network Libraries  
+=============================================  
+ General Documentation: http://tmrh20.github.io  
+   
+ Library functions are mostly the same.  
+ See the included examples for RPi specific usage  
+ 
+##Raspberry Pi - PreConfig
+    
+  
+####Possible pre-configuration:  
+  If SPI is not already enabled, load it on boot:   
+```    
+    sudo raspi-config  
+```
+A. Update the tool via the menu as required  
+B. Select Advanced and enable the SPI kernel module      
+C. Update other software and libraries:  
+```
+     sudo apt-get update  
+     sudo apt-get upgrade  
+```  
+RPi - RF24 Quick-Start  
+======================     
+A. Make a directory to contain the RF24 and possibly RF24Network lib and enter it:  
+```    
+    mkdir ~/rf24libs  
+	cd ~/rf24libs  
+```  
+B. 	Clone the RF24 Repo  
+```
+    git clone https://github.com/tmrh20/RF24.git rtemp  
+```  
+C.  Copy the RPi library folder to the current directory, and delete the rest  
+```
+	mv rtemp/RPi/RF24 ./  
+    rm -r rtemp  
+	cd RF24  
+```  
+D. Build the library, and run an example file:  
+```
+    sudo make  
+	cd examples  
+	sudo make  
+	sudo ./gettingstarted  
+```  
+	
+RPi - RF24Network Quick-Start  
+=============================  
+A. Enter the same directory that contains the RF24 library folder  
+```
+    cd ~/rf24libs  
+```  
+B. Clone the RF24Network Repo  
+```
+    git clone https://github.com/tmrh20/RF24Network.git ntemp  
+```  
+C. Copy the RF24Network folder to the current directory, and delete the rest  
+```  
+	mv rtemp/RPi/RF24Network ./  
+	rm -r ntemp  
+	cd RF24Network  
+```  
+D. Build the library  
+```
+    sudo make  
+	cd examples  
+	sudo make  
+	sudo ./helloworld_rx   OR   sudo ./helloworld_tx  
+```	  
+	
+Connection Info
+===============
+
+Using pin 15/GPIO 22 for CE, pin 24/GPIO8 (CE0) for CSN
+
+**Constructor:**
+```
+RF24 radio(RPI_V2_GPIO_P1_15,BCM2835_SPI_CS0, BCM2835_SPI_SPEED_8MHZ);
+```  
+
+**Pins:**  
+
+ |NRF24L01 |  RPI    | P1 Connector |  
+ |----- |----------- | -------------|  
+ |VCC:  	 | rpi-3v3    |    (17) |  
+ |GND:  	 | rpi-gnd    |    (25) |  
+ |CE:   	 | rpi-gpio22 |    (15) |  
+ |CSN:  	 | rpi-gpio8  |    (24) |  
+ |SCK:  	 | rpi-sckl   |    (23) |  
+ |MOSI: 	 | rpi-mosi   |    (19) |  
+ |MISO: 	 | rpi-miso   |    (21) |  
+  
+  
+****************
+  
+  
+Based on the arduino lib from J. Coliz <maniacbug@ymail.com>.  
+the library was berryfied by Purinda Gunasekara <purinda@gmail.com>.  
+then forked from github stanleyseow/RF24 to https://github.com/jscrane/RF24-rpi  
+Network lib also based on https://github.com/farconada/RF24Network
+
+Currently optimized and aligned with Arduino fork of libraries by TMRh20:  
+https://github.com/tmrh20/RF24/RPi and https://github.com/tmrh20/RF24Network/RPi  
+Documentation: http://tmrh20.github.io
+
+