Microcontroller options

There are a lot of choices but I'd say the Atmel line is a good choice
for you. They offer some traditional 8-bit RISC controllers, and some
newer 32-bit ARM-based controllers. Funnily enough, one of my selection
criteria is whether the chip is available in a DIP package, so I don't
have to solder surface mount, or invest in an expensive breakout board.
If this matters to you be sure to note the package availability when
you're looking.

-- Gordon

For what it's worth, I'm a newbie too, as anyone here will readily
attest from the way I constantly pester them with questions.  :)  I
recently went on just such a controller search myself, looking at
various boards under $50.

But, based in part on the advice of Gordon and others here, I've decided
to take the plunge and give a raw Atmel (AVR) chip a try.  These are
electronically quite easy to use; the challenge may be setting up the
development environment, but if you use Windows then you'll probably
find that pretty easy too.  If you don't, get back to me and we'll
suffer through setting up the GNU toolchain together.  :)

Here's what I just ordered from Digikey:

   Part#: ATAVRISP2-ND
   Description: PROGRAMMER AVR IN SYSTEM
   Price: $35.91

   Part#: ATMEGA48-20PU-ND
   Description: IC AVR MCU 4K 20MHZ 5V 28DIP
   Price: $2.69

The programmer is a bit on the pricey side, but you get it once and use
it over and over.  The controller itself, as you can see, is quite
cheap.  So if you screw it up and turn it into a brick, you don't suffer
too much financially.  :)

I chose this particular chip because the ATMega48 seems like a pretty
common AVR chip (it's used in one version of the Pololu Baby Orangutan
for example -- which BTW looks like a great board if you want something
with motor controllers built in).  And it's a DIP package, as Gordon
points out (important for me since I use a prototyping breadboard a
lot).  I don't know what the "20PU" or "ND" parts mean, so hopefully
they're not important!

Good luck,
- Joe

If I recall correctly, "ND" is a digikey moniker and originally
stood for "No Discount".  These days it just means it is a Digikey
part number.  The "20PU" stands for 20Mhz in a "28P3" or 28-pin
plastic .30" skinny DIP.  A good choice of part.  Before you know
it, you and your friends will be buying them in tubes of 25 to
get them at the $1.69 price point.

Not got give you buyers remorse, but I am about to add AVR's
to my bag of tools and have been hunting around for AVR programmers.
The AVRDEVKIT1-ND is a combination of the ATSTK500 and the
ATAVRDragon from Digikey at $49.00.  It is supposed to be a
combined programmer and debugger.

-Wayne

No doubt.  :)


That's OK.  I knew this wasn't a debugger when I bought it, and I'm
assuming that if I stick with AVR development, it won't be the last
programmer I buy.  But I think it's a good starter unit -- it saves me
from the temptation to try and figure out debugging while also figuring
out the rest of it!

Best,
- Joe

Joe, didn't you try the AVR Butterfly, at $19.99 from Digi-key? If so,
what was your experience programming that, regards available tools and
development environments?

I'm on my fourth myself. I actually still use the first one I ever got,
an STK200, out in the garage for some things.

-- Gordon

Yes (though I got mine through the kindness of Dennis Clark).


I never managed to get anywhere with it.  I even posted to the avrfreaks
forum, but nobody there had much in the way of specific advice.  But to
be fair, I was extremely short on both time and money at the time, so I
was attempting to use the bootloader but lacked sufficient time to
figure out how to do so.

Now that I've got an AVR-ISP2 on the way, I'll probably get the
butterfly out again.  And once I've figured out how to program it with
that, I may take another stab at the bootloader.  Especially considering
that I think I have brickedthe Coridium ARMmite board I was planning to
use as the brain of my firefighting bot...

Best,
- Joe

I'm just guessing here, but it's possible if you use regular ISP
programming on the Butterfly, then it may erase the bootloader.

????



Ummm, what is "bricked"? :-) I thought you also had the ARMexpress.

True.  But the code for the bootloader is available, and so (I am told)
could be reloaded.


Brick (v).  To render inoperable, i.e., as functional as a brick.


Yep.  But that has no A/D inputs, without which it's pretty useless, at
least for this bot.  (I will have half a dozen analog sensors measuring
distance to the walls, flame sensor signal, etc.)

Best,
- Joe

Oh, right. I can them frisbees.




Yeah, checking the notes, looks like the ARMexpressLite has 6 A/D
channels, but none on the ARMexpress.

When you say "C", you'll get a lot of advice here, but much of this -
esp regarding ARMs and AVRs - will probably involve using GNU C and
possibly Linux, or maybe one of the stripped down [free] versions of
otherwise rather expensive commercial compilers. So, this will mean
spending a fair amount of time on the learning curve regards
installing and learning to use the environments. So, it helps if
you're very familiar with programming environments, and not too
noobish, if you're gonna go that way.

IOW, there are a LOT of cheap boards around, but you need to check how
easy it is get going on the programming side. Many of the guys here
have been doing it for years, and using tough tools comes easy for
them.

So, all in all, my advice is to figure that your first robot is very
unlikely to be your last one. Therefore, I would get something that's
relatively cheap and easy to program, for my first venture, and use
that as a steppingstone to get acquainted with things. Then, once that
robot is running good, figure out where to go from there.

I've got about a dozen robots, and many of them get by fine with
simple controllers like the Basic Stamp. I don't for instance need a
Mini-ATX [powerful] board for many of them, so I have different
processors for different robots. It's nice to take a processor that
comes with a free IDE that installs instantly, and you can quickly get
going, rather than having to spend days on the initial learning curve.
My 0.02.