动手做！基于nRF24L01P的Arduino无线通信

2017-04-19 3 Comments 4,300 Views 3 Times

动手做！基于nRF24L01P的Arduino无线通信笔记。nRF24L01P是一种容易获得的、可接受的无线通信解决方案，在热门硬件上有可直接使用的库，可方便快速地应用于方案原型中。

关键词：nRF24L01+ , Arduino , 无线通信

0.序言
1.购买
2.软件准备
3.硬件相关
4.软件使用
1. 4.1 getstarted

0.序言

为了帮小崔的毕设解决nRF24L01P的实际使用问题，同时自己也有无线通信的需求（想做一个通用的无线文本显示屏），所以写了这篇记录文章。

1.购买

请注意！一定要根据项目的实际需求，购买价格合理、质量可靠的nRF24L01+。一方面买来的模块直接影响无线传输的速率和丢包率，另一方面，买来的东西要是不好用会直接影响项目的进度和心情的！

这里先记一下我的一次脑抽经历……没时间看的就直接往下拖或者点目录跳过吧

我第一次购买nRF24L01P模块时候是在淘宝上随便搜的，一看，这家店铺牛逼啊！然后一秒下单就不管了。

结果我收到货：

我靠这贴片的尺寸和我想象中的不太一样啊，震惊！然而我没有相应的转接排针

然后我花了整整一晚上的时间：

这玩意这尺寸没法用焊锡什么的……自己的锅自己背吧……

更令我震惊的是，在接下来的例程中，竟然连接正常 = =。不过因为短接的关系，大概不到10分钟它们就烧片阵亡了。。。RIP

所以一定要确认好排针的间距，还有模块的质量（这个也很重要!）

最后还是重新淘宝了新的。

2.软件准备

我使用的库是：

GitHub

https://github.com/nRF24/RF24

star数800+，支持Python、C++（Arduino和树莓派）。

3.硬件相关

看一下定义

图片取自 http://www.fabacademy.org/archives/2015/eu/students/ciurnelli.mattia/exercise13.html

与板子连接

转自 http://tmrh20.github.io/RF24/

The table below shows how to connect the the pins of the NRF24L01(+) to different boards. CE and CSN are configurable.

PIN	NRF24L01	Arduino UNO	ATtiny25/45/85 [0]	ATtiny44/84 [1]	LittleWire [2]	RPI	RPi -P1 Connector
1	GND	GND	pin 4	pin 14	GND	rpi-gnd	(25)
2	VCC	3.3V	pin 8	pin 1	regulator 3.3V required	rpi-3v3	(17)
3	CE	digIO 7（可更改）	pin 2	pin 12	pin to 3.3V	rpi-gpio22	(15)
4	CSN	digIO 8（可更改）	pin 3	pin 11	RESET	rpi-gpio8	(24)
5	SCK	digIO 13	pin 7	pin 9	SCK	rpi-sckl	(23)
6	MOSI	digIO 11	pin 6	pin 7	MOSI	rpi-mosi	(19)
7	MISO	digIO 12	pin 5	pin 8	MISO	rpi-miso	(21)
8	IRQ	-（悬空即可）	–	–	–	–	–

对于Arduino Nano型号的板子，其接线方法与UNO相同。其他板子需要查询SPI定义确认一下。

必须注意的是，RF24这个芯片必须接3.3V，接5V将立刻烧毁。切记切记！

接线后如图

4.软件使用

4.1 getstarted

用了大受欢迎的RF24的库，先使用getstarted的例程

/*
* Getting Started example sketch for nRF24L01+ radios
* This is a very basic example of how to send data from one node to another
* Updated: Dec 2014 by TMRh20
*/

#include <SPI.h>
#include "RF24.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(7,8);
/**********************************************************/

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

// Used to control whether this node is sending or receiving
bool role = 0;

void setup() {
  Serial.begin(115200);
  Serial.println(F("RF24/examples/GettingStarted"));
  Serial.println(F("*** PRESS 'T' to begin transmitting to the other node"));
  
  radio.begin();

  // Set the PA Level low to prevent power supply related issues since this is a
 // getting_started sketch, and the likelihood of close proximity of the devices. RF24_PA_MAX is default.
  radio.setPALevel(RF24_PA_LOW);
  
  // Open a writing and reading pipe on each radio, with opposite addresses
  if(radioNumber){
    radio.openWritingPipe(addresses[1]);
    radio.openReadingPipe(1,addresses[0]);
  }else{
    radio.openWritingPipe(addresses[0]);
    radio.openReadingPipe(1,addresses[1]);
  }
  
  // Start the radio listening for data
  radio.startListening();
}

void loop() {
  
  
/****************** Ping Out Role ***************************/  
if (role == 1)  {
    
    radio.stopListening();                                    // First, stop listening so we can talk.
    
    
    Serial.println(F("Now sending"));

    unsigned long start_time = micros();                             // Take the time, and send it.  This will block until complete
     if (!radio.write( &start_time, sizeof(unsigned long) )){
       Serial.println(F("failed"));
     }
        
    radio.startListening();                                    // Now, continue listening
    
    unsigned long started_waiting_at = micros();               // Set up a timeout period, get the current microseconds
    boolean timeout = false;                                   // Set up a variable to indicate if a response was received or not
    
    while ( ! radio.available() ){                             // While nothing is received
      if (micros() - started_waiting_at > 200000 ){            // If waited longer than 200ms, indicate timeout and exit while loop
          timeout = true;
          break;
      }      
    }
        
    if ( timeout ){                                             // Describe the results
        Serial.println(F("Failed, response timed out."));
    }else{
        unsigned long got_time;                                 // Grab the response, compare, and send to debugging spew
        radio.read( &got_time, sizeof(unsigned long) );
        unsigned long end_time = micros();
        
        // Spew it
        Serial.print(F("Sent "));
        Serial.print(start_time);
        Serial.print(F(", Got response "));
        Serial.print(got_time);
        Serial.print(F(", Round-trip delay "));
        Serial.print(end_time-start_time);
        Serial.println(F(" microseconds"));
    }

    // Try again 1s later
    delay(1000);
  }



/****************** Pong Back Role ***************************/

  if ( role == 0 )
  {
    unsigned long got_time;
    
    if( radio.available()){
                                                                    // Variable for the received timestamp
      while (radio.available()) {                                   // While there is data ready
        radio.read( &got_time, sizeof(unsigned long) );             // Get the payload
      }
     
      radio.stopListening();                                        // First, stop listening so we can talk   
      radio.write( &got_time, sizeof(unsigned long) );              // Send the final one back.      
      radio.startListening();                                       // Now, resume listening so we catch the next packets.     
      Serial.print(F("Sent response "));
      Serial.println(got_time);  
   }
 }




/****************** Change Roles via Serial Commands ***************************/

  if ( Serial.available() )
  {
    char c = toupper(Serial.read());
    if ( c == 'T' && role == 0 ){      
      Serial.println(F("*** CHANGING TO TRANSMIT ROLE -- PRESS 'R' TO SWITCH BACK"));
      role = 1;                  // Become the primary transmitter (ping out)
    
   }else
    if ( c == 'R' && role == 1 ){
      Serial.println(F("*** CHANGING TO RECEIVE ROLE -- PRESS 'T' TO SWITCH BACK"));      
       role = 0;                // Become the primary receiver (pong back)
       radio.startListening();
       
    }
  }


} // Loop

100

101

102

103

104

105

106

107

108

109

110

111

112

113

114

115

116

117

118

119

120

121

122

123

124

125

126

127

128

129

130

131

132

133

134

135

136

137

138

139

140

* Getting Started example sketch for nRF24L01+ radios

* This is a very basic example of how to send data from one node to another

* Updated: Dec 2014 by TMRh20

#include <SPI.h>

#include "RF24.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(7,8);

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

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

// Used to control whether this node is sending or receiving

bool role = 0;

void setup() {

Serial.begin(115200);

Serial.println(F("RF24/examples/GettingStarted"));

Serial.println(F("*** PRESS 'T' to begin transmitting to the other node"));

radio.begin();

// Set the PA Level low to prevent power supply related issues since this is a

// getting_started sketch, and the likelihood of close proximity of the devices. RF24_PA_MAX is default.

radio.setPALevel(RF24_PA_LOW);

// Open a writing and reading pipe on each radio, with opposite addresses

if(radioNumber){

radio.openWritingPipe(addresses[1]);

radio.openReadingPipe(1,addresses[0]);

}else{

radio.openWritingPipe(addresses[0]);

radio.openReadingPipe(1,addresses[1]);

}

// Start the radio listening for data

radio.startListening();

}

void loop() {

/****************** Ping Out Role ***************************/

if (role == 1) {

radio.stopListening(); // First, stop listening so we can talk.

Serial.println(F("Now sending"));

unsigned long start_time = micros(); // Take the time, and send it. This will block until complete

if (!radio.write( &start_time, sizeof(unsigned long) )){

Serial.println(F("failed"));

}

radio.startListening(); // Now, continue listening

unsigned long started_waiting_at = micros(); // Set up a timeout period, get the current microseconds

boolean timeout = false; // Set up a variable to indicate if a response was received or not

while ( ! radio.available() ){ // While nothing is received

if (micros() - started_waiting_at > 200000 ){ // If waited longer than 200ms, indicate timeout and exit while loop

timeout = true;

break;

}

if ( timeout ){ // Describe the results

Serial.println(F("Failed, response timed out."));

}else{

unsigned long got_time; // Grab the response, compare, and send to debugging spew

radio.read( &got_time, sizeof(unsigned long) );

unsigned long end_time = micros();

// Spew it

Serial.print(F("Sent "));

Serial.print(start_time);

Serial.print(F(", Got response "));

Serial.print(got_time);

Serial.print(F(", Round-trip delay "));

Serial.print(end_time-start_time);

Serial.println(F(" microseconds"));

}

// Try again 1s later

delay(1000);

}

/****************** Pong Back Role ***************************/

if ( role == 0 )

{

unsigned long got_time;

if( radio.available()){

// Variable for the received timestamp

while (radio.available()) { // While there is data ready

radio.read( &got_time, sizeof(unsigned long) ); // Get the payload

}

radio.stopListening(); // First, stop listening so we can talk

radio.write( &got_time, sizeof(unsigned long) ); // Send the final one back.

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

Serial.print(F("Sent response "));

Serial.println(got_time);

}

/****************** Change Roles via Serial Commands ***************************/

if ( Serial.available() )

{

char c = toupper(Serial.read());

if ( c == 'T' && role == 0 ){

Serial.println(F("*** CHANGING TO TRANSMIT ROLE -- PRESS 'R' TO SWITCH BACK"));

role = 1; // Become the primary transmitter (ping out)

}else

if ( c == 'R' && role == 1 ){

Serial.println(F("*** CHANGING TO RECEIVE ROLE -- PRESS 'T' TO SWITCH BACK"));

role = 0; // Become the primary receiver (pong back)

radio.startListening();

}

} // Loop

注意，使用两个Arduino，每个的通信地址需要不同，每个烧录时使用不同的地址，改动初始化的radioNumber一个为1一个为0，其它不用变，烧进去。

bool radioNumber = 0;

1	bool radioNumber = 0;

两个都通电后，打开发射端的串口监视器，发送一个T即可开始传输。效果如下

不过我的丢包率有点高啊，可能是买的廉价货的原因。

之前小崔一直实验失败，可能是其接触不良或者面包板的问题。请大家一定不要吝啬，买质量好的线材和元件。

对于一些需求和稳定性的修正，要看一下所有例程，简单看一下注释即可

Steins;Lab