Microcomputers for Homebrew Projects?

tengwar asks: "Way back when I was at university, I did a course on microcomputers which went into enough detail to design, build and program a Z80-based system - more or less state of the art at the time. Now that my lecture notes are firmly embedded in the Carboniferous layer, I'd like to have a go at doing this with a more modern chip, and I wondered what's available. I'm not brilliant at electronics, and I liked the way the Z80 peripheral chips integrated easily with the CPU. Obviously I'm not looking to just slot together the latest PC motherboard with the latest Pentium, but I'd need to go for something where the board design won't get too complicated, which probably rules out processors with full 32-bit external interfaces on space grounds. I'm not really concerned about performance, but it would be nice to be able to port a JRE to it rather than working entirely in assembler. Any thoughts on suitable starting points?"

Comments

Atmel AVR

[glassesmonkey]

I'm not sure if anything short of Pentium/Athlon would be state of the art enough, but I'd recommend the Atmel AVR. Firstly, there are lots of demo/examples with it and existing software archives exist.
This processor is used in some smart-sensor applications where you have distributed sensors.
Here's a 1998 EDN mag review and some simm circuit boards which make project computers.

microcontrollers

[wotevah]

If you forget about java and a VGA display, you can do a lot of fun things in C with a single microcontroller chip. Microchip makes an entire range of fairly cheap, very low-power microcontrollers, flash- or one-time programmable. There are also other companies that make enhanced versions of the venerable 80C51 such as the Philips 80C552 with integrated A/D converters and PWM outputs although depending on your soldering/wrapping abilities you might not want to use them as they have quite a few pins!

Microcontrollers are extremely small, low-powered devices containing a CPU, some code/data memory peripheral interfaces. You might have seen them at work in your preferred game station mod chip...

I think Motorola, AMD and Intel also have a line of powerful 68xxx- and x86-, respectively, -based microcontrollers that might be closer to the capabilities of a PC processor.

There are also some chips that you can program in Basic (ugh) via a small interpreter in their boot code. It really depends on what you are planning to do.

ARMBoards

[brejc8]

We have made a few ARM Boards to teach undergraduate students. They work with ARM Angel or with our own debugger KMD. You can write code in asm or C or any even gcc front end (inc java).
The best feature for me is the huge FPGA's to play around with. Its quite easy to pick up any electronic equipment and plug it into it. Lots of fun and great experience gaining stuff.
The board total was around 100 GBP (inc board manufacture and mounting) and I think if you ask nicely the designs will be available.

Alternatively you could use something like a 6809 or an 8051 but then writing code for them is a pain. The best idea if you use someting old is to emulate a better processor. You can then run your favorite ARM/MIPS/x86 code on an emulation and forget the real system.

Try Arm on for size

[madmaxx]

You might try an Arm processor, many of which have great built-in features (like NIC, daq, memory management). You can get demo boards, and run linux + related gnu tools on them. ARM-based systems make great embedded/distributed systems (aka 'the future'), and are a useful to learn for the old-resume.

Where to start

[jcwren]

If you *really* want a JRE (which is generally not synonymous with performance, in the microcontroller world), check out the TINI from Dallas Semiconductor, here.

If you want to get into heavier duty gear (and available only in surface mount), you can look at things like the Patriot from PTSC, here. There are also several others that I've seen, but can't recall the name of. A little Googling should find those.

Re:Not that easy

[John Hasler]

Make that a few hundred MHz and a few cm.