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

Update: TMRh20
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 if wanting
to initiate communication instead of respond to a commmunication.

/*
// March 2014 - TMRh20 - Updated along with High Speed RF24 Library fork
// Parts derived from examples by J. Coliz <maniacbug@ymail.com>
*/
#include <SPI.h>
#include "nRF24L01.h"
#include "RF24.h"
#include "printf.h"
// Hardware configuration: Set up nRF24L01 radio on SPI bus plus pins 7 & 8
RF24 radio(7,8);
// Topology
const uint64_t pipes[2] = { 0xABCDABCD71LL, 0x544d52687CLL }; // Radio pipe addresses for the 2 nodes to communicate.
// Role management: Set up role. This sketch uses the same software for all the nodes
// in this system. Doing so greatly simplifies testing.
typedef enum { role_ping_out = 1, role_pong_back } role_e; // The various roles supported by this sketch
const char* role_friendly_name[] = { "invalid", "Ping out", "Pong back"}; // The debug-friendly names of those roles
role_e role = role_pong_back; // The role of the current running sketch
// A single byte to keep track of the data being sent back and forth
byte counter = 1;
void setup(){
Serial.begin(115200);
printf_begin();
Serial.print(F("\n\rRF24/examples/pingpair_ack/\n\rROLE: "));
Serial.println(role_friendly_name[role]);
Serial.println(F("*** PRESS 'T' to begin transmitting to the other node"));
// Setup and configure rf radio
radio.begin();
radio.setAutoAck(1); // Ensure autoACK is enabled
radio.enableAckPayload(); // Allow optional ack payloads
radio.setRetries(0,15); // 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.openWritingPipe(pipes[1]); // Both radios listen on the same pipes by default, and switch when writing
radio.openReadingPipe(1,pipes[0]);
radio.startListening(); // Start listening
radio.printDetails(); // Dump the configuration of the rf unit for debugging
}
void loop(void) {
if (role == role_ping_out){
radio.stopListening(); // First, stop listening so we can talk.
printf("Now sending %d as payload. ",counter);
byte gotByte;
unsigned long time = micros(); // Take the time, and send it. This will block until complete
//Called when STANDBY-I mode is engaged (User is finished sending)
if (!radio.write( &counter, 1 )){
Serial.println(F("failed."));
}else{
if(!radio.available()){
Serial.println(F("Blank Payload Received."));
}else{
while(radio.available() ){
unsigned long tim = micros();
radio.read( &gotByte, 1 );
printf("Got response %d, round-trip delay: %lu microseconds\n\r",gotByte,tim-time);
counter++;
}
}
}
// Try again later
delay(1000);
}
// Pong back role. Receive each packet, dump it out, and send it back
if ( role == role_pong_back ) {
byte pipeNo;
byte gotByte; // Dump the payloads until we've gotten everything
while( radio.available(&pipeNo)){
radio.read( &gotByte, 1 );
radio.writeAckPayload(pipeNo,&gotByte, 1 );
}
}
// Change roles
if ( Serial.available() )
{
char c = toupper(Serial.read());
if ( c == 'T' && role == role_pong_back )
{
Serial.println(F("*** CHANGING TO TRANSMIT ROLE -- PRESS 'R' TO SWITCH BACK"));
role = role_ping_out; // Become the primary transmitter (ping out)
radio.openWritingPipe(pipes[0]);
radio.openReadingPipe(1,pipes[1]);
}
else if ( c == 'R' && role == role_ping_out )
{
Serial.println(F("*** CHANGING TO RECEIVE ROLE -- PRESS 'T' TO SWITCH BACK"));
role = role_pong_back; // Become the primary receiver (pong back)
radio.openWritingPipe(pipes[1]);
radio.openReadingPipe(1,pipes[0]);
radio.startListening();
}
}
}