Arduino以太网和DHCP无法通信到互联网

Question

我有这个Web客户端的例子，通过DHCP获取IP地址。它连接到我的路由器IP地址192.168.0.1成功，但它没有发送GET HTTP到google.com。实质上，我不能让来自Arduino的流量进入互联网。

我有一个连接到Arduino的Linksys/Cisco E2000 router。

我的代码如下。

#include <SPI.h> 
#include <Ethernet.h> 
#include <EthernetDHCP.h> 

// Enter a MAC address and IP address for your controller below. 
// The IP address will be dependent on your local network: 
byte mac[] = {0x90, 0xA2, 0xDA, 0x00, 0x78, 0x0B}; 
byte ip[] = {192, 168, 0, 125}; 
byte gateway[] = {192, 168, 0, 1}; 
byte subnet[] = {255,255,255,0}; 
byte serverLocal[] = { 192,168,0,1 }; // Google 
byte serverExternal[] = { 173,194,33,104 }; // Google 
// Initialize the Ethernet client library 
// with the IP address and port of the server 
// that you want to connect to (port 80 is default for HTTP): 
Client clientLocal(serverLocal, 80); 
Client clientExternal(serverExternal, 80); 

const char* ip_to_str(const uint8_t*); 

void setup() { 
    Serial.begin(9600); 

    Serial.println("Attempting to obtain a DHCP lease..."); 

    // Initiate a DHCP session. The argument is the MAC (hardware) address that 
    // you want your Ethernet shield to use. This call will block until a DHCP 
    // lease has been obtained. The request will be periodically resent until 
    // a lease is granted, but if there is no DHCP server on the network or if 
    // the server fails to respond, this call will block forever. 
    // Thus, you can alternatively use polling mode to check whether a DHCP 
    // lease has been obtained, so that you can react if the server does not 
    // respond (see the PollingDHCP example). 
    EthernetDHCP.begin(mac); 

    // Since we're here, it means that we now have a DHCP lease, so we print 
    // out some information. 
    const byte* ipAddr = EthernetDHCP.ipAddress(); 
    const byte* gatewayAddr = EthernetDHCP.gatewayIpAddress(); 
    const byte* dnsAddr = EthernetDHCP.dnsIpAddress(); 

    Serial.println("A DHCP lease has been obtained."); 

    Serial.print("My IP address is "); 
    Serial.println(ip_to_str(ipAddr)); 

    Serial.print("Gateway IP address is "); 
    Serial.println(ip_to_str(gatewayAddr)); 

    Serial.print("DNS IP address is "); 
    Serial.println(ip_to_str(dnsAddr)); 

    // if you get a connection, report back via serial: 
    if (clientLocal.connect()) { 
     Serial.println("connected internally"); 
     // Make a HTTP request: 
     clientLocal.println("GET /index.html HTTP/1.0"); 
     clientLocal.println(); 
    } 
    else { 
     // kf you didn't get a connection to the server: 
     Serial.println("connection failed internally"); 
    } 

    // if you get a connection, report back via serial: 
    if (clientExternal.connect()) { 
     Serial.println("connected externally"); 
     // Make a HTTP request: 
     clientExternal.println("GET /search?q=arduino HTTP/1.0"); 
     clientExternal.println(); 
    } 
    else { 
     // kf you didn't get a connection to the server: 
     Serial.println("connection failed externally"); 
    } 
} 

void loop() 
{ 
    // if there are incoming bytes available 
    // from the server, read them and print them: 
    if (clientLocal.available()) { 
     char c = clientLocal.read(); 
     Serial.print(c); 
    } 

    // if the server's disconnected, stop the client: 
    if (!clientLocal.connected()) { 
     Serial.println(); 
     Serial.println("disconnecting."); 
     clientLocal.stop(); 
    } 

    // if there are incoming bytes available 
    // from the server, read them and print them: 
    if (clientLocal.available()) { 
     char c = clientLocal.read(); 
     Serial.print(c); 
    } 

    // if the server's disconnected, stop the client: 
    if (!clientExternal.connected()) { 
     Serial.println(); 
     Serial.println("disconnecting."); 
     clientExternal.stop(); 

     // do nothing forevermore: 
     for(;;) 
      ; 
    } 
} 

// Just a utility function to nicely format an IP address. 
const char* ip_to_str(const uint8_t* ipAddr) 
{ 
    static char buf[16]; 
    sprintf(buf, "%d.%d.%d.%d\0", ipAddr[0], ipAddr[1], ipAddr[2], ipAddr[3]); 
    return buf; 
} 

Answer 1

这里是一个example of working code（也许你用它作为源？）。我能看到的唯一区别是行：

if (clientLocal.connect()) { 

我怀疑附加Serial.begin()有任何影响，但delay()可以需要（尽管这是一个漫长：

Serial.begin(9600); 
delay(1000); 

之前的行镜头...）