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AN S-7600A/PIC16F877 JOURNEY

Part 3: Hot-Wiring the System
by Fred Eady

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The absolute last thing I ever thought Iıd be doing with a PIC is using one to communicate over the Internet. Way back in the early ı80s, I was enthralled with the PIC16C55. What more could an embedded engineer want or need? This puppy had lots of I/O pins and program memory galore! Shucks! I could turn on LEDs and flip relays all day with a minimal amount of thought or code. One of the neatest tricks was making a virtual UART so the PIC could talk to the 20-MHz desktopıs serial port running Visual Basic 3 on Win3.1.

Times have truly changed. When I designed my first PIC programmer for the PIC16C5x parts, the Microchip assembler was not a freebie. In fact, I still remember the Microchip rep calling me in the middle of the night with the price for the assembler. It was a whopping $99.95 and came on a 5.25ı floppy. Immediately I replied, "How am I going to sell that with my programmer kit when the PIC programmer hardware only costs $69?" No problem. I hung up the phone, got out of bed, and started writing my own PIC assembler. The rest is still attempting to make history.

Today, the Microchip MPLAB suite is free for downloading, and the new PIC parts like the PIC16F877 on the S-7600A/PIC16F877 Internet Engine are sporting in-circuit programmable flash memory with four times the program memory and I/O space of the lowly but popular PIC16C55. I was running a BBS then, as the Internet had not yet become a household item. Now, the Internet is the driving force behind much of todayıs technology. PIC compilers are abundant and PIC programmers are everywhere. So, thereıs nothing to keep an embedded designer from putting his or her device on the ıNet. In fact, the PIC tools have become sophisticated enough to allow the embedded engineer to concentrate on the end productıs functionality. The days of building the tools followed by the application are over.

Another offshoot of the Internet revolution is the proliferation of knowledge. Every RFC (request for comment) is available for immediate viewing via the Internet. In addition, applications relevant to particular RFCs are also available. Every day, companies like iReady are taking the rudimentary elements of the Internet defined by the RFCs and packaging them in silicon. The S-7600A Internet data pump is one good example of this. Itıs a lot of TCP/IP and PPP functionality confined to a small space. Last time, I showed you how to employ the iReady and Microchip parts on the S-7600A/PIC16F877 Internet Engine as a cigarette pack-sized HTTP web server. This time, using the same PIC-based hardware, Iıll show you how to electronically say "The checkıs in the mail."

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