Basic Library
Digital I/O
Analog I/O
Advanced I/O
Time
Math
Trigonometry
Random Numbers
Bits and Bytes
Interrupts
Serial Comm.
Standard Library
Servo Motor
Stepping Motor
Liquid Crystal
EEPROM
SPI
I2C (Wire)
SD Card
SD (File Operations)
Ethernet
Ethernet (Server)
Ethernet (Client)
Firmata
Periodic Operation
Power Save
Clock (RTC)
SoftwareSerial
Utility
Ethernet Server
This library enables the creation of a server that listens for incoming connections on the specified port.
EthernetServer()
Description
Constructor to create a server.
Syntax (Example)
EthernetServer server(uint16_t port)
Parameters
The port to listen on (uint16_t)
begin
Description
Tells the server to begin listening for incoming connections.
Syntax
server.begin()
Parameters
None
Returns
None
available
Description
Gets a client that is connected to the server and has data available for reading. The connection persists when the returned client object goes out of scope.
Syntax
server.available()
Parameters
None
Returns
Returns a Client object; if no Client has data available for reading, this object will evaluate to false in an if-statement.
write
Description
Write data to all the clients connected to a server. This data is sent as a byte or series of bytes.
Syntax
server.write(val)
server.write(buf, len)Parameters
val: A value to send as a single byte (byte or char)
buf: An array to send as a series of bytes (byte or char)
len: The length of the bufferReturns
Byte
write() returns the number of bytes written. It is not necessary to read this.
Description
Print data to all the clients connected to a server. Prints numbers as a sequence of digits, each an ASCII character (e.g. the number 123 is sent as the three characters '1', '2', '3').
Syntax
server.print(data)
server.print(data, BASE)Parameters
data: The data to print (char, byte, int, long, or string)
BASE (optional): The base in which to print numbers: BIN for binary (base 2), DEC for decimal (base 10), OCT for octal (base 8), HEX for hexadecimal (base 16)Returns
Byte
print() will return the number of bytes written, though reading that number is optional.
println
Description
Print data, followed by a newline, to all the clients connected to a server. Prints numbers as a sequence of digits, each an ASCII character (e.g. the number 123 is sent as the three characters '1', '2', '3').
Syntax
server.println()
server.println(data)
server.println(data, BASE)Parameters
data (optional): The data to print (char, byte, int, long, or string)
BASE (optional): The base in which to print numbers: BIN for binary (base 2), DEC for decimal (base 10), OCT for octal (base 8), HEX for hexadecimal (base 16).Returns
Byte
println() will return the number of bytes written, though reading that number is optional.
Sample Program
Here is an example for the Ethernet Server library. The server returns to a client the result of analogRead A0-A5.
#include <Arduino.h>
#include <SPI.h>
#include <Ethernet.h>
// Enter a MAC address and IP address for your controller below.
// The IP address will be dependent on your local network:
byte mac[] = {
0xDE, 0xAD, 0xBE, 0xEF, 0xFE, 0xED };
IPAddress ip(192,168,1,177);
// Initialize the Ethernet server library
// with the IP address and port you want to use
// (port 80 is default for HTTP):
EthernetServer server(80);
void setup() {
// Open serial communications and wait for port to open:
Serial.begin(9600);
while (!Serial) {
; // wait for serial port to connect. Needed for Leonardo only
}
// start the Ethernet connection and the server:
Ethernet.begin();
server.begin();
Serial.print("server is at ");
Serial.println(Ethernet.localIP());
}
void loop() {
// listen for incoming clients
EthernetClient client = server.available();
if (client) {
Serial.println("new client");
// an http request ends with a blank line
boolean currentLineIsBlank = true;
while (client.connected()) {
if (client.available()) {
char c = client.read();
Serial.write(c);
// if you've gotten to the end of the line (received a newline
// character) and the line is blank, the http request has ended,
// so you can send a reply
if (c == '\n' && currentLineIsBlank) {
// send a standard http response header
client.println("HTTP/1.1 200 OK");
client.println("Content-Type: text/html");
client.println("Connection: close"); // the connection will be closed after completion of the response
client.println("Refresh: 5"); // refresh the page automatically every 5 sec
client.println();
client.println("<!DOCTYPE HTML>");
client.println("<html>");
// output the value of each analog input pin
for (int analogChannel = 0; analogChannel < 6; analogChannel++) {
int sensorReading = analogRead(analogChannel);
client.print("analog input ");
client.print(analogChannel);
client.print(" is ");
client.print(sensorReading);
client.println("</br>");
}
client.println("</html>");
break;
}
if (c == '\n') {
// you're starting a new line
currentLineIsBlank = true;
}
else if (c != '\r') {
// you've gotten a character on the current line
currentLineIsBlank = false;
}
}
}
// give the web browser time to receive the data
delay(1);
// close the connection:
client.stop();
Serial.println("client disconnected");
}
}