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THE ETHERNET DEVELOPMENT BOARD

Part 1: Putting it all Together
by Fred Eady

Start ý Overview ý Elmerýs Silicon Glue ý Time to Kill ý The CS8900A-CQ ý Software and Firmware ý ICSP and LVP ý Assemble the Ethernet Electronics ý No Floating Allowed ý Installing the Bypass Capacitors ý Pin Point ý Finishing Installation ý Assemble the PIC16F877 Electronics ý The Rest of the Project ý Winding Down ý Finishing Up ý Sources and PDF

OVERVIEW

The Ethernet Development Board presented in this article is the most basic of configurations the Cirrus Logic CS8900A-CQ can participate in. There are no fluff components, and everything that can be done with software or firmware is done that way (Iýll provide the object code and more explanation in Part 2).

The microcontroller of choice for the Ethernet Development Board is the Microchip PIC16F877. The ý877 was chosen because it can be easily programmed in-circuit using a minimum of external hardware. In addition, the ý877 is flash memory-based and does not require UV erase cycles common to quartz windowed devices. A comprehensive ý877 programming application is provided to allow the user to read, write, and erase the ý877 in-circuit using only the parallel port of a standard personal computer running Windows98. You may also use the PIC16F874 if you canýt get your hands on an ý877.

For universal compatibility, the transport mechanism is standard Ethernet with IP protocol encapsulated in the data area of the Ethernet frame. Real TCP/IP functionality is nonexistent as there is no formal TCP/IP stack implemented in the firmware. Thus, all data transfers I will describe in the text are based on UDP format. There is nothing to prevent you from inventing your own protocols and signaling methods.

There are no trick parts, and every piece of the Ethernet Development Board can be purchased from suppliers you see in either Circuit Cellar or Circuit Cellar Online. For the convenience of those who wish to build this project economically, Iýve supplied a complete kit and support via the EDTP web site at www.edtp.com.

This segment will concentrate on assembling the Ethernet Development Board. Along the way, hardware theory will be offered with recommendations, personal experiences, and construction tips. Part 2 will deal with the PC application program specifics and the generation of the Ethernet driver firmware for the PIC16F877. The ultimate goal is to provide a user-constructable alternative data transport mechanism that is in many ways superior to serial and parallel data transfer methods commonly used today.

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