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/*
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. Created Dec 2014 - TMRh20 */
/**
* Example of using interrupts * * This is a very simple example of using two devices to communicate using interrupts. * With multiple devices, each device would need to have a separate reading pipe */
#include <SPI.h>
#include "RF24.h"
#include <printf.h>
// Hardware configuration
// Set up nRF24L01 radio on SPI bus plus pins 7 & 8
RF24 radio(7,8); // Use the same address for both devices
uint8_t address[] = { "radio" };
// Simple messages to represent a 'ping' and 'pong'
uint8_t ping = 111; uint8_t pong = 222;
volatile uint32_t round_trip_timer = 0;
/********************** Setup *********************/
void setup(){
Serial.begin(115200); Serial.println(F("Simple pingpair example")); Serial.println(F("Send a 'T' via Serial to transmit a single 'ping' ")); //printf_begin();
// Setup and configure rf radio
radio.begin();
// Use dynamic payloads to improve response time
radio.enableDynamicPayloads(); radio.openWritingPipe(address); // communicate back and forth. One listens on it, the other talks to it.
radio.openReadingPipe(1,address); radio.startListening(); //radio.printDetails(); // Dump the configuration of the rf unit for debugging
attachInterrupt(0, check_radio, LOW); // Attach interrupt handler to interrupt #0 (using pin 2) on BOTH the sender and receiver
}
/********************** Main Loop *********************/ void loop() {
if(Serial.available()){ switch(toupper(Serial.read())){ case 'T': // Only allow 1 transmission per 45ms to prevent overlapping IRQ/reads/writes
// Default retries = 5,15 = ~20ms per transmission max
while(micros() - round_trip_timer < 45000){ //delay between writes
} Serial.print(F("Sending Ping")); radio.stopListening(); round_trip_timer = micros(); radio.startWrite( &ping, sizeof(uint8_t),0 ); break; } } }
/********************** Interrupt *********************/
void check_radio(void) // Receiver role: Does nothing! All the work is in IRQ
{ bool tx,fail,rx; radio.whatHappened(tx,fail,rx); // What happened?
// If data is available, handle it accordingly
if ( rx ){ if(radio.getDynamicPayloadSize() < 1){ // Corrupt payload has been flushed
return; } // Read in the data
uint8_t received; radio.read(&received,sizeof(received));
// If this is a ping, send back a pong
if(received == ping){ radio.stopListening(); // Normal delay will not work here, so cycle through some no-operations (16nops @16mhz = 1us delay)
for(uint32_t i=0; i<130;i++){ __asm__("nop\n\t""nop\n\t""nop\n\t""nop\n\t""nop\n\t""nop\n\t""nop\n\t""nop\n\t""nop\n\t""nop\n\t""nop\n\t""nop\n\t""nop\n\t""nop\n\t""nop\n\t""nop\n\t"); } radio.startWrite(&pong,sizeof(pong),0); Serial.print("pong"); }else // If this is a pong, get the current micros()
if(received == pong){ round_trip_timer = micros() - round_trip_timer; Serial.print(F("Received Pong, Round Trip Time: ")); Serial.println(round_trip_timer); } }
// Start listening if transmission is complete
if( tx || fail ){ radio.startListening(); Serial.println(tx ? F(":OK") : F(":Fail")); } }
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