树莓派与Arduino Leonardo使用NRF24L01无线模块通信之基于RF24库 (二) 发送自定义数据

在我的项目里，树莓派主要作为中心节点，用于接收数据，Arduino作为子节点，用于发送数据，考虑到以后会有很多子节点，但又不至于使得代码过于繁琐，因此所有的传输数据添加一个头部编号用于区分不同节点。

nrf24l01支持的数据最大为4个字节，因此使用最高位的一个字节（8位）作为节点编号，剩余三个字节用于传输数据。以下为具体代码：

Arduino Leonardo程序

主要用于发送数据给树莓派，同时接收树莓派的响应数据。

#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 = 0;

/* Hardware configuration: Set up nRF24L01 radio on SPI bus plus pins 7 & 8 */
RF24 radio(9,10);
/**********************************************************/

byte addresses[][6] = {"1Node","2Node"};

// Used to control whether this node is sending or receiving
bool role = 1;

//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 = 1;
unsigned long head = 0x01000000;//高8位为头标志，根据标志不同区分不同发送源，0x00为中心主节点
unsigned long receData;

void setup() {
  Serial.begin(57600);
  printf_begin();
  Serial.println(F("RF24/examples/GettingStarted"));
  
  radio.begin();

  radio.setPALevel(RF24_PA_MAX);
  radio.openWritingPipe(pipes);
  
}

void loop() {
  unsigned long data = sendData+head;
   Serial.print("Sending:");
   Serial.println(data);
   bool ok = radio.write(&data,sizeof(unsigned long));

   if(ok){
      radio.startListening();
      delay(925); //延时，用于响应返回时间
      if(radio.available()){
          radio.read(&receData,sizeof(unsigned long));//读取的数据为1时，表示正常
          Serial.print("Response:");
          Serial.println(receData);
        }
      radio.stopListening();
    }

} // Loop

 结果如下：

　　

树莓派程序

树莓派主要用于接收数据，同时发出响应。

#include <cstdlib>
#include <iostream>
#include <sstream>
#include <string>
#include <unistd.h>
#include <RF24/RF24.h>

using namespace std;
//
// Hardware configuration
// Configure the appropriate pins for your connections

/****************** Raspberry Pi ***********************/

// Radio CE Pin, CSN Pin, SPI Speed

// Setup for GPIO 22 CE and CE0 CSN with SPI Speed @ 4Mhz
//RF24 radio(RPI_V2_GPIO_P1_22, BCM2835_SPI_CS0, BCM2835_SPI_SPEED_4MHZ);

// NEW: Setup for RPi B+
//RF24 radio(RPI_BPLUS_GPIO_J8_15,RPI_BPLUS_GPIO_J8_24, BCM2835_SPI_SPEED_8MHZ);

// Setup for GPIO 15 CE and CE0 CSN with SPI Speed @ 8Mhz
//RF24 radio(RPI_V2_GPIO_P1_15, RPI_V2_GPIO_P1_24, BCM2835_SPI_SPEED_8MHZ);

// RPi generic:
RF24 radio(22,0);

/*** RPi Alternate ***/
//Note: Specify SPI BUS 0 or 1 instead of CS pin number.
// See http://tmrh20.github.io/RF24/RPi.html for more information on usage

//RPi Alternate, with MRAA
//RF24 radio(15,0);

//RPi Alternate, with SPIDEV - Note: Edit RF24/arch/BBB/spi.cpp and  set 'this->device = "/dev/spidev0.0";;' or as listed in /dev
//RF24 radio(22,0);


/****************** Linux (BBB,x86,etc) ***********************/

// Setup for ARM(Linux) devices like BBB using spidev (default is "/dev/spidev1.0" )
//RF24 radio(115,0);

//BBB Alternate, with mraa
// CE pin = (Header P9, Pin 13) = 59 = 13 + 46 
//Note: Specify SPI BUS 0 or 1 instead of CS pin number. 
//RF24 radio(59,0);

/********** User Config *********/
// Assign a unique identifier for this node, 0 or 1
bool radioNumber = 1;

/********************************/

// Radio pipe addresses for the 2 nodes to communicate.
const uint64_t pipes = 0xE8E8F0F0E1LL;

unsigned long  receData;
unsigned long  respData=0x01;
unsigned long  head=0x00000000;
int main(int argc, char** argv){

  cout << "RF24/examples/GettingStarted/
";

  // Setup and configure rf radio
  radio.begin();
  // optionally, increase the delay between retries & # of retries
  radio.setRetries(15,15);
  // Dump the configuration of the rf unit for debugging
  radio.printDetails();
  
  radio.openReadingPipe(1,pipes);
/***********************************/
  // This simple sketch opens two pipes for these two nodes to communicate
  // back and forth.

  radio.startListening();

  cout << "Listening .... 
";
  // forever loop
  while (1)
  {
  // Pong back role.  Receive each packet, dump it out, and send it back
  //

  // if there is data ready
  if ( radio.available() )
  {

    // Fetch the payload, and see if this was the last one.
    while(radio.available()){
        radio.read( &receData, sizeof(unsigned long) );
    }
    radio.stopListening();
    unsigned long data = respData+head;            
    radio.write( &data, sizeof(unsigned long) );

    // Now, resume listening so we catch the next packets.
    radio.startListening();

    // Spew it
    printf("Got payload(%d) %lu...
",sizeof(unsigned long), receData);
                
    delay(925); //Delay after payload responded to, minimize RPi CPU time
                
    }    

  } // forever loop

  return 0;
}

 结果如下：

上图中数据“16777217”用八进制表示为“0x01000001”,第一个字节的0x01表示从节点head=0x01000000发来的数据，数据为data=0x000001。