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

This sketch is a more complex example of using the RF24 library for Arduino. Deploy this on up to six nodes. Set one as the 'pong receiver' by tying the role_pin low, and the others will be 'ping transmit' units. The ping units unit will send out the value of millis() once a second. The pong unit will respond back with a copy of the value. Each ping unit can get that response back, and determine how long the whole cycle took.

This example requires a bit more complexity to determine which unit is which. The pong receiver is identified by having its role_pin tied to ground. The ping senders are further differentiated by a byte in eeprom.

/*
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.
*/
#include <SPI.h>
#include <EEPROM.h>
#include "nRF24L01.h"
#include "RF24.h"
#include "printf.h"
//
// Hardware configuration
//
// Set up nRF24L01 radio on SPI bus plus pins 9 & 10
RF24 radio(9,10);
// sets the role of this unit in hardware. Connect to GND to be the 'pong' receiver
// Leave open to be the 'pong' receiver.
const int role_pin = 7;
//
// Topology
//
// Radio pipe addresses for the nodes to communicate. Only ping nodes need
// dedicated pipes in this topology. Each ping node has a talking pipe
// that it will ping into, and a listening pipe that it will listen for
// the pong. The pong node listens on all the ping node talking pipes
// and sends the pong back on the sending node's specific listening pipe.
const uint64_t talking_pipes[5] = { 0xF0F0F0F0D2LL, 0xF0F0F0F0C3LL, 0xF0F0F0F0B4LL, 0xF0F0F0F0A5LL, 0xF0F0F0F096LL };
const uint64_t listening_pipes[5] = { 0x3A3A3A3AD2LL, 0x3A3A3A3AC3LL, 0x3A3A3A3AB4LL, 0x3A3A3A3AA5LL, 0x3A3A3A3A96LL };
//
// Role management
//
// Set up role. This sketch uses the same software for all the nodes
// in this system. Doing so greatly simplifies testing. The hardware itself specifies
// which node it is.
//
// This is done through the role_pin
//
// The various roles supported by this sketch
typedef enum { role_invalid = 0, role_ping_out, role_pong_back } role_e;
// The debug-friendly names of those roles
const char* role_friendly_name[] = { "invalid", "Ping out", "Pong back"};
// The role of the current running sketch
role_e role;
//
// Address management
//
// Where in EEPROM is the address stored?
const uint8_t address_at_eeprom_location = 0;
// What is our address (SRAM cache of the address from EEPROM)
// Note that zero is an INVALID address. The pong back unit takes address
// 1, and the rest are 2-6
uint8_t node_address;
void setup(void)
{
//
// Role
//
// set up the role pin
pinMode(role_pin, INPUT);
digitalWrite(role_pin,HIGH);
delay(20); // Just to get a solid reading on the role pin
// read the address pin, establish our role
if ( digitalRead(role_pin) )
role = role_ping_out;
else
role = role_pong_back;
//
// Address
//
if ( role == role_pong_back )
node_address = 1;
else
{
// Read the address from EEPROM
uint8_t reading = EEPROM.read(address_at_eeprom_location);
// If it is in a valid range for node addresses, it is our
// address.
if ( reading >= 2 && reading <= 6 )
node_address = reading;
// Otherwise, it is invalid, so set our address AND ROLE to 'invalid'
else
{
node_address = 0;
role = role_invalid;
}
}
//
// Print preamble
//
Serial.begin(115200);
printf_begin();
printf("\n\rRF24/examples/starping/\n\r");
printf("ROLE: %s\n\r",role_friendly_name[role]);
printf("ADDRESS: %i\n\r",node_address);
//
// Setup and configure rf radio
//
radio.begin();
//
// Open pipes to other nodes for communication
//
// The pong node listens on all the ping node talking pipes
// and sends the pong back on the sending node's specific listening pipe.
if ( role == role_pong_back )
{
radio.openReadingPipe(1,talking_pipes[0]);
radio.openReadingPipe(2,talking_pipes[1]);
radio.openReadingPipe(3,talking_pipes[2]);
radio.openReadingPipe(4,talking_pipes[3]);
radio.openReadingPipe(5,talking_pipes[4]);
}
// Each ping node has a talking pipe that it will ping into, and a listening
// pipe that it will listen for the pong.
if ( role == role_ping_out )
{
// Write on our talking pipe
radio.openWritingPipe(talking_pipes[node_address-2]);
// Listen on our listening pipe
radio.openReadingPipe(1,listening_pipes[node_address-2]);
}
//
// Start listening
//
radio.startListening();
//
// Dump the configuration of the rf unit for debugging
//
radio.printDetails();
//
// Prompt the user to assign a node address if we don't have one
//
if ( role == role_invalid )
{
printf("\n\r*** NO NODE ADDRESS ASSIGNED *** Send 1 through 6 to assign an address\n\r");
}
}
void loop(void)
{
//
// Ping out role. Repeatedly send the current time
//
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
unsigned long time = millis();
printf("Now sending %lu...",time);
radio.write( &time, sizeof(unsigned long) );
// 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 > 250 )
timeout = true;
// Describe the results
if ( timeout )
{
printf("Failed, response timed out.\n\r");
}
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\r",got_time,millis()-got_time);
}
// Try again 1s later
delay(1000);
}
//
// Pong back role. Receive each packet, dump it out, and send it back
//
if ( role == role_pong_back )
{
// if there is data ready
uint8_t pipe_num;
if ( radio.available(&pipe_num) )
{
// Dump the payloads until we've gotten everything
unsigned long got_time;
bool done = false;
while (!done)
{
// Fetch the payload, and see if this was the last one.
done = radio.read( &got_time, sizeof(unsigned long) );
// Spew it
printf("Got payload %lu from node %i...",got_time,pipe_num+1);
}
// First, stop listening so we can talk
radio.stopListening();
// Open the correct pipe for writing
radio.openWritingPipe(listening_pipes[pipe_num-1]);
// Retain the low 2 bytes to identify the pipe for the spew
uint16_t pipe_id = listening_pipes[pipe_num-1] & 0xffff;
// Send the final one back.
radio.write( &got_time, sizeof(unsigned long) );
printf("Sent response to %04x.\n\r",pipe_id);
// Now, resume listening so we catch the next packets.
radio.startListening();
}
}
//
// Listen for serial input, which is how we set the address
//
if (Serial.available())
{
// If the character on serial input is in a valid range...
char c = Serial.read();
if ( c >= '1' && c <= '6' )
{
// It is our address
EEPROM.write(address_at_eeprom_location,c-'0');
// And we are done right now (no easy way to soft reset)
printf("\n\rManually reset address to: %c\n\rPress RESET to continue!",c);
while(1) ;
}
}
}
// vim:ai:ci sts=2 sw=2 ft=cpp