Arduino Sketches: Tools and Techniques for Programming Wizardry

CHAPTER9

Ethernet

This chapter discusses the begin() function. The hardware required to run the examples in this chapter includes:

• Arduino Uno
• Arduino Ethernet Shield
• Light Dependent Resistor

You can find the code download for this chapter at http://www.wiley.com/go/arduinosketches on the Download Code tab. The code is in the Chapter 9 folder and the filenames are:

• Chapter9client.ino
• Chapter9server.ino

Introduction

The first personal computers were not connected to each other; they were standalone devices, designed to calculate input from a user and to output the result of calculations to the same user. When files needed to be transferred from one machine to another, floppy disks were used.

The advances made in computer science also meant that files became bigger; because computers had more memory and could do faster calculations, the results could also be bigger. Soon, disks became too small to exchange information. Precious time was lost when data was to be retrieved; a desktop computer simply could not store all the information it required, and when modifications were made to a file on one computer, other computers would not be aware of changes. It became obvious that this had to change and that computers had to talk between themselves.

Serial communication had been used before computers existed and was an early means of connecting two computers. However, its speed made this type of link impractical. In addition, it could connect only two computers to each other. Engineers ...