Ethernet Shield DHCP Address Printer

Get an IP address via DHCP and print it out.

This sketch uses the DHCP extensions to the Ethernet library to get an IP address via DHCP and print the address obtained using an Arduino Ethernet shield.

DHCP is used to assign an IP address when Ethernet.begin(mac) is called. Using DHCP significantly increases the size of a sketch. Using the localIP() function, the assigned IP address is sent out via the Serial Monitor.

Hardware Required

Circuit

The Ethernet shield allows you to connect a WIZNet Ethernet controller to the Arduino boards via the SPI bus. It uses the ICSP header pins and pin 10 as chip select for the SPI connection to the Ethernet controller chip. Later models of the Ethernet shield also have an SD Card on board. Digital pin 4 is used to control the chip select pin on the SD card.

The shield should be connected to a network with an Ethernet cable. You will need to change the network settings in the program to correspond to your network.

The circuit for this tutorial.
The circuit for this tutorial.

Image developed using Fritzing. For more circuit examples, see the Fritzing project page

In the above image, the Arduino board would be stacked below the Ethernet shield.

Code

1/*
2
3 DHCP-based IP printer
4
5 This sketch uses the DHCP extensions to the Ethernet library
6
7 to get an IP address via DHCP and print the address obtained.
8
9 using an Arduino Wiznet Ethernet shield.
10
11 Circuit:
12
13 Ethernet shield attached to pins 10, 11, 12, 13
14
15 created 12 April 2011
16
17 modified 9 Apr 2012
18
19 by Tom Igoe
20
21 modified 02 Sept 2015
22
23 by Arturo Guadalupi
24
25 */
26
27#include <SPI.h>
28#include <Ethernet.h>
29
30// Enter a MAC address for your controller below.
31// Newer Ethernet shields have a MAC address printed on a sticker on the shield
32byte mac[] = {
33
34 0x00, 0xAA, 0xBB, 0xCC, 0xDE, 0x02
35};
36
37void setup() {
38
39 // You can use Ethernet.init(pin) to configure the CS pin
40
41 //Ethernet.init(10); // Most Arduino shields
42
43 //Ethernet.init(5); // MKR ETH shield
44
45 //Ethernet.init(0); // Teensy 2.0
46
47 //Ethernet.init(20); // Teensy++ 2.0
48
49 //Ethernet.init(15); // ESP8266 with Adafruit Featherwing Ethernet
50
51 //Ethernet.init(33); // ESP32 with Adafruit Featherwing Ethernet
52
53 // Open serial communications and wait for port to open:
54
55 Serial.begin(9600);
56
57 while (!Serial) {
58
59 ; // wait for serial port to connect. Needed for native USB port only
60
61 }
62
63 // start the Ethernet connection:
64
65 Serial.println("Initialize Ethernet with DHCP:");
66
67 if (Ethernet.begin(mac) == 0) {
68
69 Serial.println("Failed to configure Ethernet using DHCP");
70
71 if (Ethernet.hardwareStatus() == EthernetNoHardware) {
72
73 Serial.println("Ethernet shield was not found. Sorry, can't run without hardware. :(");
74
75 } else if (Ethernet.linkStatus() == LinkOFF) {
76
77 Serial.println("Ethernet cable is not connected.");
78
79 }
80
81 // no point in carrying on, so do nothing forevermore:
82
83 while (true) {
84
85 delay(1);
86
87 }
88
89 }
90
91 // print your local IP address:
92
93 Serial.print("My IP address: ");
94
95 Serial.println(Ethernet.localIP());
96}
97
98void loop() {
99
100 switch (Ethernet.maintain()) {
101
102 case 1:
103
104 //renewed fail
105
106 Serial.println("Error: renewed fail");
107
108 break;
109
110 case 2:
111
112 //renewed success
113
114 Serial.println("Renewed success");
115
116 //print your local IP address:
117
118 Serial.print("My IP address: ");
119
120 Serial.println(Ethernet.localIP());
121
122 break;
123
124 case 3:
125
126 //rebind fail
127
128 Serial.println("Error: rebind fail");
129
130 break;
131
132 case 4:
133
134 //rebind success
135
136 Serial.println("Rebind success");
137
138 //print your local IP address:
139
140 Serial.print("My IP address: ");
141
142 Serial.println(Ethernet.localIP());
143
144 break;
145
146 default:
147
148 //nothing happened
149
150 break;
151
152 }
153}

Last revision 2018/09/07 by SM

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