The AVR Files
Since discovering the AVR microprocessors I've abandoned development of the 68HC11 projects, mainly due to cost and having to have EPROMS for program memory. If you've looked at my main page you will se a link to a temperature sensor Atmega8 data collection page. Nice and simple to do and collects useful(?) data. Since then I've put together a couple of things and leant a lot. Obviously I used Linux and the avr-gcc toolchain which requires very little effort to use and is widely described on the web. Some explanation about makefiles will be posted here soon as it's not immediatley obvious how the various memory areas are written to. Not to me at least.
Programming the chips at first appeared to be simple however, on setting fuse bits to enable highr processor speeds I found the simple parrallel programming cable and avrdude was incapapble of programming the chip of the CPU speed was set to greater than 4MHz. I'd read of problems on the vaious news groups, none provided an answer to the issue. Looking at the waveform on a 'scope I could see that the rise time on the signal lines was very slow, which suggested that there may be an issue with faster chips. I'd also found several buffered parallell programming interfaces but the one with the best description was at http://www.aplomb.nl/TechStuff/PPPD/PPPD%20English.html but the schematic was not in any easily importable format, i.e Eagle. So I set about copying and slightly adapting it in an Eagle schematic, built it and am now using it program my chips. Looking at the 'scope trace I see nice square clock pulses so it is definately better than before. Incidentally, I made the board using a Roland Modela engraver using information from http://fablab.marcboon.com/pcb/. I'll document the issues I had with that process too! There were many unexpected issues to deal with and several scrap PCBs produced.
The schematic and brd files are available. I tried to reduce the number of links to a minimum, if you can do better send me the improved board file.