Fix for issue 62, adding DHCP support. New begin() method added to EthernetClass which takes just a MAC address and gets the rest of its configuration information via DHCP. Examples updated to use the IPAddress class and some have been changed to get their config via DHCP.

libraries/Ethernet/examples/UdpNtpClient/UdpNtpClient.pde

@@ -20,13 +20,11 @@
 #include <Ethernet.h>
 #include <Udp.h>
 
-// Enter a MAC address and IP address for your controller below.
-// The IP address will be dependent on your local network:
+// Enter a MAC address for your controller below.
+// Newer Ethernet shields have a MAC address printed on a sticker on the shield
 byte mac[] = {  
   0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED };
 
-IPAddress ip(192, 168, 1, 177);
-
 unsigned int localPort = 8888;      // local port to listen for UDP packets
 
 IPAddress timeServer(192, 43, 244, 18); // time.nist.gov NTP server
@@ -40,11 +38,16 @@ UDP Udp;
 
 void setup() 
 {
-  // start Ethernet and UDP
-  Ethernet.begin(mac,ip);
-  Udp.begin(localPort);
-
   Serial.begin(9600);
+
+  // start Ethernet and UDP
+  if (Ethernet.begin(mac) == 0) {
+    Serial.println("Failed to configure Ethernet using DHCP");
+    // no point in carrying on, so do nothing forevermore:
+    for(;;)
+      ;
+  }
+  Udp.begin(localPort);
 }
 
 void loop()
@@ -99,7 +102,7 @@ void loop()
 }
 
 // send an NTP request to the time server at the given address 
-unsigned long sendNTPpacket(byte *address)
+unsigned long sendNTPpacket(IPAddress& address)
 {
   // set all bytes in the buffer to 0
   memset(packetBuffer, 0, NTP_PACKET_SIZE);