Overview

So far, the microcontroller Web server has been using a serial Serial Line Internet Protocol (SLIP) network interface. The next step is to adapt the server for use with Ethernet, and this chapter describes those adaptations.

Unfortunately, do-it-yourself hardware construction techniques are no longer applicable. A few chips hand-soldered on a prototyping board may have been adequate so far, but the use of 100-pin flatpack components puts you in a different hardware league. To provide a standard hardware base, I'll use the Microchip PICDEM.net ^[1] for all Ethernet experimentation, although the software could be adapted to other microcontroller networking platforms.

The Microchip PICDEM.net board also has a small amount of analog and digital I/O and an LCD display. These will be used for diagnostic purposes, although they are not essential to the operation of the networking software.

Hardware

Demonstration Board

The demonstration board (Figure 12.1) has the following peripherals:

• two-line by 16-character alphanumeric LCD display

• two analog potentiometers

• user push button

• three light-emitting diodes (LEDs): one marked "system," two marked "user"

• 32Kb serial E2ROM

• Ethernet interface

• RS232 serial interface.

Figure 12.1: Ethernet demonstration board.

It would be difficult to drive all these peripherals using the same PIC16C76 as before. Instead, the 40-pin PIC16F877 is employed, which has

• 8K 14-bit words Flash program memory

• 368 bytes data memory

• 256 bytes nonvolatile E2ROM

• eight-level hardware stack

• 10-bit analog-to-digital converter

• Synchronous and asynchronous communication ports

• three timers