Ethernet Shield Chat Server

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1/*
2
3 Chat Server
4
5 A simple server that distributes any incoming messages to all
6
7 connected clients.  To use, telnet to your device's IP address and type.
8
9 You can see the client's input in the serial monitor as well.
10
11 Using an Arduino Wiznet Ethernet shield.
12
13 Circuit:
14
15 * Ethernet shield attached to pins 10, 11, 12, 13
16
17 created 18 Dec 2009
18
19 by David A. Mellis
20
21 modified 9 Apr 2012
22
23 by Tom Igoe
24
25 */
26
27#include <SPI.h>
28#include <Ethernet.h>
29
30// Enter a MAC address and IP address for your controller below.
31// The IP address will be dependent on your local network.
32// gateway and subnet are optional:
33byte mac[] = {
34
35  0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED };
36
37IPAddress ip(192, 168, 1, 177);
38
39IPAddress myDns(192, 168, 1, 1);
40
41IPAddress gateway(192, 168, 1, 1);
42
43IPAddress subnet(255, 255, 0, 0);
44
45// telnet defaults to port 23
46
47EthernetServer server(23);
48
49bool alreadyConnected = false; // whether or not the client was connected previously
50
51void setup() {
52
53  // You can use Ethernet.init(pin) to configure the CS pin
54
55  //Ethernet.init(10);  // Most Arduino shields
56
57  //Ethernet.init(5);   // MKR ETH shield
58
59  //Ethernet.init(0);   // Teensy 2.0
60
61  //Ethernet.init(20);  // Teensy++ 2.0
62
63  //Ethernet.init(15);  // ESP8266 with Adafruit Featherwing Ethernet
64
65  //Ethernet.init(33);  // ESP32 with Adafruit Featherwing Ethernet
66
67  // initialize the ethernet device
68
69  Ethernet.begin(mac, ip, myDns, gateway, subnet);
70
71  // Open serial communications and wait for port to open:
72
73  Serial.begin(9600);
74
75   while (!Serial) {
76
77    ; // wait for serial port to connect. Needed for native USB port only
78
79  }
80
81  // Check for Ethernet hardware present
82
83  if (Ethernet.hardwareStatus() == EthernetNoHardware) {
84
85    Serial.println("Ethernet shield was not found.  Sorry, can't run without hardware. :(");
86
87    while (true) {
88
89      delay(1); // do nothing, no point running without Ethernet hardware
90
91    }
92
93  }
94
95  if (Ethernet.linkStatus() == LinkOFF) {
96
97    Serial.println("Ethernet cable is not connected.");
98
99  }
100
101  // start listening for clients
102
103  server.begin();
104
105  Serial.print("Chat server address:");
106
107  Serial.println(Ethernet.localIP());
108}
109
110void loop() {
111
112  // wait for a new client:
113
114  EthernetClient client = server.available();
115
116  // when the client sends the first byte, say hello:
117
118  if (client) {
119
120    if (!alreadyConnected) {
121
122      // clear out the input buffer:
123
124      client.flush();
125
126      Serial.println("We have a new client");
127
128      client.println("Hello, client!");
129
130      alreadyConnected = true;
131
132    }
133
134    if (client.available() > 0) {
135
136      // read the bytes incoming from the client:
137
138      char thisChar = client.read();
139
140      // echo the bytes back to the client:
141
142      server.write(thisChar);
143
144      // echo the bytes to the server as well:
145
146      Serial.write(thisChar);
147
148    }
149
150  }
151}