ForceTronics: Creating a nRF24L01 Transceiver Network

In this video we will look at how to create an nRF24L01 Transceiver module network (more than two). This is useful if you want to build a wireless sensor network or some type of wireless automation system that has multiple wireless nodes.

***************************Arduino Code for Receiver*******************************
//This sketch is from a tutorial video for networking more than two nRF24L01 tranciever modules on the ForceTronics YouTube Channel
//the code was leverage from the following code http://maniacbug.github.io/RF24/starping_8pde-example.html
//This sketch is free to the public to use and modify at your own risk

#include <SPI.h> //Call SPI library so you can communicate with the nRF24L01+
#include <nRF24L01.h> //nRF2401 libarary found at https://github.com/tmrh20/RF24/
#include <RF24.h> //nRF2401 libarary found at https://github.com/tmrh20/RF24/

const int pinCE = 9; //This pin is used to set the nRF24 to standby (0) or active mode (1)
const int pinCSN = 10; //This pin is used to tell the nRF24 whether the SPI communication is a command or message to send out
byte daNumber = 0; //The number that the transmitters are trying to guess
RF24 wirelessSPI(pinCE, pinCSN); // Declare object from nRF24 library (Create your wireless SPI)
const uint64_t rAddress[] = {0xB00B1E50D2LL, 0xB00B1E50C3LL}; //Create pipe addresses for the 2 nodes to recieve data, the "LL" is for LongLong type
const uint64_t wAddress[] = {0xB00B1E50B1LL, 0xB00B1E50A4LL}; //Create pipe addresses for the 2 nodes to transmit data, the "LL" is for LongLong type

void setup()
{
randomSeed(analogRead(0)); //create unique seed value for random number generation
daNumber = (byte)random(11); //Create random number that transmitters have to guess
Serial.begin(57600); //start serial to communication
Serial.print("The number they are trying to guess is: ");
Serial.println(daNumber); //print the number that they have to guess
Serial.println();
wirelessSPI.begin(); //Start the nRF24 module
wirelessSPI.openReadingPipe(1,rAddress[0]); //open pipe o for recieving meassages with pipe address
wirelessSPI.openReadingPipe(2,rAddress[1]); //open pipe o for recieving meassages with pipe address
wirelessSPI.startListening(); // Start listening for messages
}

void loop()
{
byte pipeNum = 0; //variable to hold which reading pipe sent data
byte gotByte = 0; //used to store payload from transmit module

while(wirelessSPI.available(&pipeNum)){ //Check if recieved data
wirelessSPI.read( &gotByte, 1 ); //read one byte of data and store it in gotByte variable
Serial.print("Recieved guess from transmitter: ");
Serial.println(pipeNum); //print which pipe or transmitter this is from
Serial.print("They guess number: ");
Serial.println(gotByte); //print payload or the number the transmitter guessed
if(gotByte != daNumber) { //if true they guessed wrong
Serial.println("Fail!! Try again.");
}
else { //if this is true they guessed right
if(sendCorrectNumber(pipeNum)) Serial.println("Correct! You're done."); //if true we successfully responded
else Serial.println("Write failed"); //if true we failed responding
}
Serial.println();
}

delay(200);
}

//This function turns the reciever into a transmitter briefly to tell one of the nRF24s
//in the network that it guessed the right number. Returns true if write to module was
//successful
bool sendCorrectNumber(byte xMitter) {
bool worked; //variable to track if write was successful
wirelessSPI.stopListening(); //Stop listening, stop recieving data.
wirelessSPI.openWritingPipe(wAddress[xMitter-1]); //Open writing pipe to the nRF24 that guessed the right number
if(!wirelessSPI.write(&daNumber, 1)) worked = false; //write the correct number to the nRF24 module, and check that it was recieved
else worked = true; //it was recieved
wirelessSPI.startListening(); //Switch back to a reciever
return worked; //return whether write was successful
}

***************************Arduino Code for Transmitter 1****************************

//This sketch is from a tutorial video for networking more than two nRF24L01 tranciever modules on the ForceTronics YouTube Channel

//the code was leverage from the following code http://maniacbug.github.io/RF24/starping_8pde-example.html

//This sketch is free to the public to use and modify at your own risk

#include <SPI.h> //Call SPI library so you can communicate with the nRF24L01+

#include <nRF24L01.h> //nRF2401 libarary found at https://github.com/tmrh20/RF24/

#include <RF24.h> //nRF2401 libarary found at https://github.com/tmrh20/RF24/

const int pinCE = 9; //This pin is used to set the nRF24 to standby (0) or active mode (1)

const int pinCSN = 10; //This pin is used to tell the nRF24 whether the SPI communication is a command or message to send out

byte counter = 1; //used to count the packets sent

bool done = false; //used to know when to stop sending packets

RF24 wirelessSPI(pinCE, pinCSN); // Create your nRF24 object or wireless SPI connection

const uint64_t wAddress = 0xB00B1E50D2LL; // Pipe to write or transmit on

const uint64_t rAddress = 0xB00B1E50B1LL; //pipe to recive data on

void setup()

{

Serial.begin(57600); //start serial to communicate process

randomSeed(analogRead(0)); //create unique seed value for random number generation

wirelessSPI.begin(); //Start the nRF24 module

wirelessSPI.openWritingPipe(wAddress); //open writing or transmit pipe

wirelessSPI.openReadingPipe(1,rAddress); //open reading or recieve pipe

wirelessSPI.stopListening(); //go into transmit mode

}

void loop()

{

if(!done) { //true once you guess the right number

byte randNumber = (byte)random(11); //generate random guess between 0 and 10

if (!wirelessSPI.write( &randNumber, 1 )){ //if the write fails let the user know over serial monitor

Serial.println("Guess delivery failed");

}

else { //if the write was successful

Serial.print("Success sending guess: ");

Serial.println(randNumber);

wirelessSPI.startListening(); //switch to recieve mode to see if the guess was right

unsigned long startTimer = millis(); //start timer, we will wait 200ms

bool timeout = false;

while ( !wirelessSPI.available() && !timeout ) { //run while no recieve data and not timed out

if (millis() - startTimer > 200 ) timeout = true; //timed out

}

if (timeout) Serial.println("Last guess was wrong, try again"); //no data to recieve guess must have been wrong

else { //we recieved something so guess must have been right

byte daNumber; //variable to store recived value

wirelessSPI.read( &daNumber,1); //read value

if(daNumber == randNumber) { //make sure it equals value we just sent, if so we are done

Serial.println("You guessed right so you are done");

done = true; //signal to loop that we are done guessing

}

else Serial.println("Something went wrong, keep guessing"); //this should never be true, but just in case

}

wirelessSPI.stopListening(); //go back to transmit mode

}

delay(1000);

}

***************************Arduino Code for Transmitter 2****************************