Arduino网络编程实战-Ethernet篇-CoAP客户端

CoAP客户端

Arduino Ethernet Shield V1 允许 Arduino 板连接到互联网。它基于 Wiznet W5100ethernet 芯片（数据表）。 Wiznet W5100 提供支持 TCP 和 UDP 的网络 (IP) 堆栈。它最多支持四个同时套接字连接。

本次实例将演示如何实现一个简单的CoAP客户端。

1、硬件准备

Arduino Mega 2560
Arduino Ethernet Shield
路由器（推荐可以上网、开启DHCP）
网线一条
电脑一台

2、软件准备

Arduino IDE
网络调试软件（推荐使用通信猫)
支持库：https://github.com/hirotakaster/CoAP-simple-library
Nodejs
Nodejs CoAP支持库：node-coap npm -g install coap
Nodejs 日期支持库：node-datetime npm -g install node-datetime

3、代码实现

1）Arduino端的CoAP客户端

#include <SPI.h>
#include <Dhcp.h>
#include <Dns.h>
#include <Ethernet.h>
#include <EthernetUdp.h>
#include <coap-simple.h>

#define USE\_STATIC 0
byte mac[] = {
  0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED
};
#if USE\_STATIC
IPAddress ip(192, 168, 0, 177);
#endif

// CoAP 响应回调
void callback\_response(CoapPacket &packet, IPAddress ip, int port);

void callback\_response(CoapPacket &packet, IPAddress ip, int port) {
  Serial.println("[Coap Response got]");

  char p[packet.payloadlen + 1];
  memcpy(p, packet.payload, packet.payloadlen);
  p[packet.payloadlen] = NULL;

  Serial.println(p);
}

EthernetUDP Udp;
Coap coap(Udp);

void setup() {
  
   Serial.begin(115200);
   Serial.println("Ethernet CoAP Client Example");
   
#if USE\_STATIC
   Ethernet.begin(mac,ip);
#else
  Ethernet.begin(mac);
#endif

   if (Ethernet.hardwareStatus() == EthernetNoHardware) {
    Serial.println("Ethernet shield was not found. Sorry, can't run without hardware. :(");
    while (true) {
      delay(1); 
    }
  }
  if (Ethernet.linkStatus() == LinkOFF) {
    Serial.println("Ethernet cable is not connected.");
    while(true){
      delay(1);  
    }
  }

  Serial.print("IP:");
  Serial.println(Ethernet.localIP());
  Serial.print("Subnet Mask:");
  Serial.println(Ethernet.subnetMask());
  Serial.print("Gateway:");
  Serial.println(Ethernet.gatewayIP());
  Serial.print("DNS Server:");
  Serial.println(Ethernet.dnsServerIP());

  coap.response(callback_response);

  // start coap server/client
  coap.start();
}

void loop() {
  Serial.println("Send Request:time");
  int msgid = coap.get(IPAddress(192, 168, 0, 130), 5683, "time");

  delay(1000);
  coap.loop();
}

2）Nodejs端的CoAP服务器

const coap = require('coap') // or coap
const server = coap.createServer()
var datetime = require('node-datetime');

server.on('request', (req, res) => {
	var req_path = req.url.split('/')[1];
	console.log('client request:' + req_path)
	if(req_path == 'time'){
		var dt = datetime.create();
		var formatted = dt.format('Y/m/d H:M:S');
		res.end(formatted);
		console.log('[response]:' + formatted);
	}else{
		res.end('[hello]\n')
	}
	
    
})

server.listen(() => {
    console.log('server started')
})