THE ETHERNET DEVELOPMENT BOARD

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	THE ETHERNET DEVELOPMENT BOARD
Part 2: The Software and Firmware Exposed by Fred Eady Start ı The Basics ı Registers ı Bus Interface Registers ı Status and Control Registers ı InitChip ı Initiate Transmit Registers ı Address Filter Registers ı Receive and Transmit Frame Locations ı CS8900A-CQ Transmit and Receive Operations ı The Next Read ı Broadcast ı ARP ı No Cheating ı Tiger Woodsı Putter ı Whatıs the Point? ı And It Programs, Too! ı Sources and PDF REGISTERS There are numerous CS8900A-CQ registers. The best way to keep up with them is to predefine them and use labels that are readable. Beginning with the PacketPage I/O port definitions, all of the internal CS8900A-CQ registers are listed and defined whether or not they are used. Labels beginning with "pageport" represent the 16 base PacketPage I/O ports listed in Listing 3. PacketPage internal registers that are accessed using the PacketPage I/O ports are prefixed by "ppage." This area is where the initialization registers are located. Also, youıll find the counters and status registers in the grouping you see in Listing 4. There are five PacketPage event registers and they are defined by their datasheet names. Some of the CS8900A-CQ registers have names that are simply too long to attempt to code with. I tried to make those register names and their internal bit settings as readable as possible. These long-named registers include: ı PacketPage self control ı PacketPage self status ı PacketPage bus control ı PacketPage bus status ı PacketPage line control ı PacketPage test control ı PacketPage receiver configuration ı PacketPage receiver event ı PacketPage receiver control ı PacketPage transmit configuration ı PacketPage transmit event ı PacketPage transmit command ı PacketPage buffer configuration The aforementioned registers and register sets can be simplified into six major categories, bus interface registers, status and control registers, initiate transmit registers, address filter registers, receive frame location, and transmit frame location. The six categories, including all of their subsets, can be found within the 4K area called PacketPage. PREVIOUS • NEXT Circuit Cellar provides up-to-date information for engineers. Visit www.circuitcellar.com for more information and additional articles. For subscription information, call (860) 875-2199, subscribe@circuitcellar.com or subscribe online. ıCircuit Cellar, the Magazine for Computer Applications. Posted with permission.