This was originally built as an A-level electronics project to control various household devices by a modem link, but the master control unit involved functions as a general purpose 68000 microprocessor based single board computer (SBC). It is for this reason that I decided to make the design freely available, as an example of a simple working 68000 system, including a full write up of how it was designed, and why various decisions were taken.
The rest of the home automation system is also detailed here for those who are interested, but it is not really a very good example. It consists of an RF data link which was intended to be transmitted along mains wiring, but was only tested for a wire transmission. At each end of the link were PIC based microcontroller modules acting as custom data link controllers, and one end as a microprocessor interface and the other as a remote appliance controller.
![[A picture of the microprocessor system]](picsmall.jpg)
The microprocessor board.
Click here for a bigger 122K photo and guided tour.
The main features of the 68000 board are:
- 8MHz 68000 processor.
- 16K 100ns static RAM.
- 16K 100ns static RAM with PC parallel port interface, effectively behaving as EPROM erasable and programmable in situ.
- 6821 Peripheral Interface Adapter driving 6818 Real Time Clock and a small keypad.
- 6850 Asynchronous Communications Interface Adapter based serial port with external clock generation, 300 to 307200 bps.
- 6522 Versatile Interface Adapter, driving PIC controlled data link and other external devices.
- 16 bit wide output port, connected to LED display.
- 8 bit wide input port, connected to DIP switches.
For more information, a brief summary of the whole project is available.
The write-up
The write-up of the project, approximately 135 pages in total, has been split into two sections, each of which are available in two formats:
The PDF (Portable Document Format) versions have been produced by passing the PostScript printer driver output through Adobe Distiller (thanks to the online Internet Distiller). These should be used in preference for most printing and viewing on screen - they have been found to be usable with Adobe Acrobat Reader and XPDF (RISC OS version).
The PostScript versions should only be used if you have trouble viewing or printing the PDF versions. Due to size constraints, they lack some of the bitmap diagrams present in the PDF versions. They are present here as GZipped Level 1 Postscript files, so first need to be decompressed with GZip or WinZip. Once this has been done, they can be viewed using Ghostscript or printed to a PostScript printer.
The write-up is split into two sections:
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The first section describes the 68000 system, with circuit diagrams and test programs included in the text.
Download: PostScript (114K) or PDF (156K)
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The second section covers the rest of the home automation system, including data link and PIC based modules. It also contains a brief description of the main program, a listing of it, an evaluation of the system and various references and acknowledgements. The RF data link I designed in 1996 has some serious issues that makes it not very usable, so I don't recommend using part as an example, but the rest should be useful.
Download: PostScript (111K) or PDF (383K)
The zipped source code (15K) is also available.
The author of the project can be contacted as below:
Page by Theo Markettos (email at theo [at@] markettos.org.uk), last modified 2009-07-19
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