Optimized High Speed NRF24L01+ Driver Class Documenation  V1.0
TMRh20 2014 - Optimized Fork of NRF24L01+ Driver

New: TMRh20
This example demonstrates the use of and extended timeout period and auto-retries/auto-reUse to increase reliability in noisy or low signal scenarios.

Write this sketch to two different nodes. Put one of the nodes into 'transmit' mode by connecting with the serial monitor and sending a 'T'. The data
transfer will begin, with the receiver displaying the payload count and the data transfer rate.

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.
#include <SPI.h>
#include "nRF24L01.h"
#include "RF24.h"
#include "printf.h"
/************* USER Configuration *****************************/
RF24 radio(7,8); // Set up nRF24L01 radio on SPI bus plus pins 7 & 8
unsigned long timeoutPeriod = 3000; // Set a user-defined timeout period. With auto-retransmit set to (15,15) retransmission will take up to 60ms and as little as 7.5ms with it set to (1,15).
// With a timeout period of 1000, the radio will retry each payload for up to 1 second before giving up on the transmission and starting over
const uint64_t pipes[2] = { 0xABCDABCD71LL, 0x544d52687CLL }; // Radio pipe addresses for the 2 nodes to communicate.
byte data[32]; //Data buffer
volatile unsigned long counter;
unsigned long rxTimer,startTime, stopTime, payloads = 0;
bool TX=1,RX=0,role=0, transferInProgress = 0;
void setup(void) {
radio.begin(); // Setup and configure rf radio
radio.setChannel(1); // Set the channel
radio.setPALevel(RF24_PA_LOW); // Set PA LOW for this demonstration. We want the radio to be as lossy as possible for this example.
radio.setDataRate(RF24_1MBPS); // Raise the data rate to reduce transmission distance and increase lossiness
radio.setAutoAck(1); // Ensure autoACK is enabled
radio.setRetries(2,15); // Optionally, increase the delay between retries. Want the number of auto-retries as high as possible (15)
radio.setCRCLength(RF24_CRC_16); // Set CRC length to 16-bit to ensure quality of data
radio.openWritingPipe(pipes[0]); // Open the default reading and writing pipe
radio.startListening(); // Start listening
radio.printDetails(); // Dump the configuration of the rf unit for debugging
printf("\n\rRF24/examples/Transfer Rates/\n\r");
printf("*** PRESS 'T' to begin transmitting to the other node\n\r");
randomSeed(analogRead(0)); //Seed for random number generation
for(int i=0; i<32; i++){
data[i] = random(255); //Load the buffer with random data
radio.powerUp(); //Power up the radio
void loop(void){
if(role == TX){
delay(2000); // Pause for a couple seconds between transfers
printf("Initiating Extended Timeout Data Transfer\n\r");
unsigned long cycles = 1000; // Change this to a higher or lower number. This is the number of payloads that will be sent.
unsigned long transferCMD[] = {'H','S',cycles }; // Indicate to the other radio that we are starting, and provide the number of payloads that will be sent
radio.writeFast(&transferCMD,12); // Send the transfer command
if(radio.txStandBy(timeoutPeriod)){ // If transfer initiation was successful, do the following
startTime = millis(); // For calculating transfer rate
boolean timedOut = 0; // Boolean for keeping track of failures
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.writeBlocking(&data,32,timeoutPeriod)){ // If retries are failing and the user defined timeout is exceeded
timedOut = 1; // Indicate failure
counter = cycles; // Set the fail count to maximum
break; // Break out of the for loop
stopTime = millis(); // Capture the time of completion or failure
//This should be called to wait for completion and put the radio in standby mode after transmission, returns 0 if data still in FIFO (timed out), 1 if success
if(timedOut){ radio.txStandBy(); } //Partially blocking standby, blocks until success or max retries. FIFO flushed if auto timeout reached
else{ radio.txStandBy(timeoutPeriod); } //Standby, block until FIFO empty (sent) or user specified timeout reached. FIFO flushed if user timeout reached.
Serial.println("Communication not established"); //If unsuccessful initiating transfer, exit and retry later
float rate = cycles * 32 / (stopTime - startTime); //Display results:
Serial.print("Transfer complete at "); Serial.print(rate); printf(" KB/s \n\r");
Serial.print(" of ");
Serial.print(cycles); Serial.println(" Packets Failed to Send");
counter = 0;
if(role == RX){
if(!transferInProgress){ // If a bulk data transfer has not been started
radio.read(&data,32); //Read any available payloads for analysis
if(data[0] == 'H' && data[4] == 'S'){ // If a bulk data transfer command has been received
payloads = data[8]; // Read the first two bytes of the unsigned long. Need to read the 3rd and 4th if sending more than 65535 payloads
payloads |= data[9] << 8; // This is the number of payloads that will be sent
counter = 0; // Reset the payload counter to 0
transferInProgress = 1; // Indicate it has started
startTime = rxTimer = millis(); // Capture the start time to measure transfer rate and calculate timeouts
if(radio.available()){ // If in bulk transfer mode, and a payload is available
radio.read(&data,32); // Read the payload
rxTimer = millis(); // Reset the timeout timer
counter++; // Keep a count of received payloads
if(millis() - rxTimer > timeoutPeriod){ // If no data available, check the timeout period
Serial.println("Transfer Failed"); // If per-payload timeout exceeeded, end the transfer
transferInProgress = 0;
if(counter >= payloads){ // If the specified number of payloads is reached, transfer is completed
startTime = millis() - startTime; // Calculate the total time spent during transfer
float numBytes = counter*32; // Calculate the number of bytes transferred
Serial.print("Rate: "); // Print the transfer rate and number of payloads
Serial.println(" KB/s");
printf("Payload Count: %d \n\r", counter);
transferInProgress = 0; // End the transfer as complete
// Change roles
if ( Serial.available() )
char c = toupper(Serial.read());
if ( c == 'T' && role == RX )
role = TX; // Become the primary transmitter (ping out)
else if ( c == 'R' && role == TX )
role = RX; // Become the primary receiver (pong back)