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AN S-7600A/PIC16F877 JOURNEY

Part 2: Revving It Up
by Fred Eady

Start ı Tera Term Pro ı Road Test ı The Hardware ı As a Web Server ı Branching Out ı Making Changes ı ReadyıSet? ı Go ı Sources and PDF

AS A WEB SERVER

The S-7600Aıs protocol stack allows the S-7600A/PIC16F877 Internet Engine to play many roles. In addition to a web server, the S-7600A/PIC16F877 Internet Engine can be configured as a TCP/IP client or an e-mail generator. In this section, Iım going to show you how the S-7600A/PIC16F877 Internet Engine can be programmed to serve a simple web page.

The process begins with the menu you see in Photo 4. After the username, password, and ISP phone number are entered, the date and time can be set and an HTML page can be loaded into the serial EEPROM. Iıve supplied a sample HTML page in Listing 3. The time and date are taken from the DS1629 and inserted into the page just before it is served.

Listing 4 is the code necessary to implement the web server application on the S-7600A/PIC16F877 Internet Engine. Letıs start at the top and work our way down. As an experienced PIC programmer, I found the PCW C package refreshing. The engineers at Microchip were good enough to provide most of the supporting include code that does the housework. All of the EEPROM, S-7600A, and PIC16F877 include files were provided by Microchip. So, building up the S-7600A/PIC16F877 Internet Engine and the accompanying software was like working with Lego blocks. The remainder of include files are the standard C includes with PIC accents that come with the PCW compiler.

I know how to write all of those I²C and serial drivers, but itıs great to have them already written for you. As you can see in Listing 4, the serial and I²C ports are defined with a simple line of code for each. The standard_io declarations help avoid a common problem with PIC I/O. PIC I/O is so fast that reads and writes to the same pin can sometimes overlap. The use of standard_io makes sure this wonıt happen by setting the I/O pin for either input or output before the operation is performed. This operation gives the I/O pin time to settle and assures a good read or write to that pin. The rest of the pre-main area is standard stuff. The normal PIC pin definitions are followed by the variable defines.

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