考虑到项目的实际需要，树莓派作为主机，应该只在需要的时候查询特定节点发送的数据，因此接收到数据后需要根据头部判断是否是自己需要的数据，如果不是继续接收数据，超过一定时间未查询到特定节点的数据，则退出程序，避免无限等待。
本项目中各个节点和树莓派的通信不区分信道，因此如果由树莓派发送给特定节点的数据会被所有节点接收到，因此子节点可以判别该数据是否发给自己的，需要在数据的第二个字节中加入目标节点的编号（第一个字节为源节点的编号）。
树莓派代码
如下：
#include <cstdlib>
#include <iostream>
#include <sstream>
#include <string>
#include <unistd.h>
#include <RF24/RF24.h> using namespace std; RF24 radio(,,BCM2835_SPI_SPEED_8MHZ); /********** User Config *********/
// Assign a unique identifier for this node, 0 or 1
bool radioNumber = ;
bool role = ;//receive mode
unsigned long start_time=millis();
unsigned long count=;
/********************************/ // Radio pipe addresses for the 2 nodes to communicate.
const uint64_t pipes = 0xE8E8F0F0E1LL; unsigned long receData;
unsigned long respData=0x01;
unsigned long srchead=0x00000000; int main(int argc, char** argv){ cout << "RF24/examples/GettingStarted/\n"; // Setup and configure rf radio
radio.begin();
// optionally, increase the delay between retries & # of retries
radio.setRetries(,);
// Dump the configuration of the rf unit for debugging
radio.printDetails(); radio.openReadingPipe(,pipes);
/***********************************/
// This simple sketch opens two pipes for these two nodes to communicate
// back and forth. radio.startListening(); cout << "Listening .... \n"; int node = atoi(argv[]); cout << "Listening Node is : " <<node<<" \n"; while(){
unsigned long end_time = millis();
if(radio.available()){
radio.read(&receData,sizeof(unsigned long));
//cout<<"receData is: "<<receData<<"\n";
unsigned int check = (unsigned int) receData>>;
unsigned long data = receData & 0x0000ffff;
//cout<<"check is "<<check<<"\n";
if(check==node && (receData & 0x00ff0000)==srchead){
cout<<"Get Node Data: "<<data<<",Time consume "<<(end_time-start_time)<<"ms \n";
break;
}
} cout<<"time out is "<<(end_time-start_time)<<"\n";
if((end_time-start_time)>=){
cout<<"Wait Data from Node "<<node<<" time out \n";
break;
} }
return ;
}
输入指令：sudo ./receive_once 1，参数1表示要查询的节点节点。得到以下结果：
Arduino Leonardo代码
Arduino Leonardo作为子节点，代码与前一节一样，不停发送和接收相互切换。如下：
#include <SPI.h>
#include "RF24.h"
#include <SPI.h>
#include "RF24.h"
#include <printf.h>
/****************** User Config ***************************/
/*** Set this radio as radio number 0 or 1 ***/
bool radioNumber = ; /* Hardware configuration: Set up nRF24L01 radio on SPI bus plus pins 7 & 8 */
RF24 radio(,);
/**********************************************************/ byte addresses[][] = {"1Node","2Node"}; // Used to control whether this node is sending or receiving
bool role = ;//1表示发送模式，0表示接收模式
unsigned long start_time = millis(); //这个是我们即将建立的传输渠道编码
//!!要和另一个模块的一致
const uint64_t pipes = 0xE8E8F0F0E1LL; //这个变量会保持我们接受到的信息
//变量类型一定要和传过来的一样
//要传输的数据
unsigned long sendData = ;
unsigned long srchead = 0x01000000;//高16位为头标志，前8位为源节点，后8位为目的节点。根据标志不同区分不同发送源，00为中心主节点
unsigned long deshead = 0x00000000;//高16位为头标志，前8位为源节点，后8位为目的节点。根据标志不同区分不同发送源，00为中心主节点
unsigned long receData; void setup() {
pinMode(,OUTPUT);//指示灯
Serial.begin();
printf_begin();
Serial.println(F("RF24/examples/GettingStarted")); radio.begin(); radio.setPALevel(RF24_PA_MAX);
radio.openWritingPipe(pipes); } void loop() {
Serial.print("role:");
Serial.println(role);
if(role){
unsigned long data = sendData+srchead+deshead;
Serial.print("Sending:");
Serial.println(data);
digitalWrite(,HIGH);
bool ok = radio.write(&data,sizeof(unsigned long)); role = ;
radio.startListening();
radio.openReadingPipe(1,pipes);
start_time = millis(); }
if(!role){
digitalWrite(,LOW);
if(radio.available()){
radio.read(&receData,sizeof(unsigned long)); //根据目标节点，判断是否是发给自己的，如果是，执行相关操作
unsigned long check = receData & 0x00ff0000;
if(check == srchead){
//接收到来自主机的数据，执行相关操作
Serial.print("Response:");
Serial.println(receData);
}
role = ;
radio.stopListening();
radio.openWritingPipe(pipes);
}else{
unsigned long end_time = millis();
if((end_time-start_time)>=){
role = ;
radio.stopListening();
radio.openWritingPipe(pipes);
}
}
} } // Loop