Electronic Supplies, Microcontroller choice question.

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I'm an amateur and I'd want to start by creating my own PCB development
board, not actually go out and buy one but make one, design in FreePCB
and then ship it off for fabrication. I've decided that the best way to
go is to start on a breadboard and then design the PCB after manual
verification, at least go as far as I can go.

First what type of microcontroller should I use? I want something
that's well supported, stable and is capable of running uCLinux (not
absolutely required but would be nice). I've been looking into Texas
Instruments, Freescale, and Microchip products. Most importantly is the
compiler availablity. There needs to be a free compiler, I'm already
spending enough money on parts, to go along with the chip. I have
experience using 6812 processors but I'd prefer to move on beyond that.
Other than that the microcontroller just needs to be flexible if it has
some extra bells and whistles that's perfectly fine, I'm not trying to
build an ultra low power device, at least not yet.

One major thing I'm confused about is all these packaging types like
SOIC and so on, I understand PDIP and that's pretty much it. And how
would I get them on the breadboard?

I probably need a new soldering iron, preferably a fine tip one which
ones are good? Not sure too much about branding in the electronics

Lastly, what's a list of some websites to get electronic supplies?

Re: Electronic Supplies, Microcontroller choice question.

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Hi Jez.
go to www.google.co.uk and type in electronic+parts. or
electronic+components. You`ll be able to browse for days, and enjoy.

Re: Electronic Supplies, Microcontroller choice question.

On Wed, 07 Dec 2005 02:32:58 -0800, jeremyje@gmail.com wrote:

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Jeremy, this group mostly deals with PCs and their problems.  Read some of
the recent posts.

I hope you get some helpful responses here, but you're more likely to get
help in comp.arch.embedded, etc.  And try googling for "microcontrollers"
and you'll find a lot of resources.

Good luck!


Re: Electronic Supplies, Microcontroller choice question.

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I've built an entire processor design on a breadboard. I used
the biggest breadboard available at the time (about 1 square foot).
I need a couple thousand pieces of wire. What I found was,
every time I turned on the power, a couple of the connections
would be bad, and I had to wiggle the wires to get it to work.
In fact the circuit was correct, but the wires were a PITA.
(I was able to run a couple hundred instruction hand assembled
program on it, driving a calculator display for readout.)

My processor ran at a very low speed, compared to today's processors
(about 3MHz). The breadboard is unsuited to high speed signal
transmission, and the only practical way to prototype, is to
build a proper circuit board. Thus, it may take you two tries
to get a decent working circuit, designing a PCB both times.

To make your circuit work well, you will need to understand
transmission line theory, and how to plan a multilayer board
stackup. A lot of cheap motherboards, are signal-power-gnd-signal
and the outside signal layers are microstrip transmission lines.
If you don't understand transmission line theory, I can guarantee
you your design will be junk (i.e. crash city).

In the old days, we used to build two layer logic boards, and in
that case, power distribution was done with copper tracks arranged
in a grid pattern. But, gridded power distribution, and chips with
fast edge rates and switching speeds (like DRAM) don't mix. That
is why four layer boards were invented, and why they are used for
motherboards. They are simply the best cheap technology for the job.

I'm gauging my opinion here, on your description of attempting
to run a Linux. Certainly, if you had a very small circuit,
with modest signal tranmission speeds, a two layer board might
still be made to work out. I'm assuming you'll be attempting
to do something aggressive in the hardware, and as such, planning
a "good offense" (four layer board, understanding transmission
line theories and how to do series terminations) will go a long
way in making your project a success. Back when I started working,
there was a lack of good advice, and so a lot of what we use
today, has been learned a bit at a time over the years. Now,
you buy a copy of this, and you're an instant genius...

"High-Speed Digital Design
 A Handbook of Black Magic"
Howard W. Johnson


You're going to need a lot more than a new soldering iron...


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