AVR-Chat

Philip Hahn wrote:
>
> Mr Graham and others,
>
> My apologies on the long delayed response. My kids got sick this
> weekend, then my wife, and now I have succumbed!
>
> I am planning on getting into **mobile** robotics. Off-topic, but I
> have this prototying system called Fischertechnik, which is a neat
> system often called "legos for adults" but is really more than that.
> It's often used in colleges for industrial prototyping and sometimes
> in industry as well. Google can help you if you are interested in
> learning more (or ask me :) ). I have motors, sensors, etc. that I've
> acquired over the years, and as I've mentioned, I've used other
> microcontrollers in the past, but AVR's look very intriguing and it
> looks possible to start relatively cheap.
>
> (answering all of you guys at once, this might get long and confusing)
>
> I don't know how much programming space I need, having never targeted
> a AVR before! I'd like to program using the gcc toolchain if possible,
> and I realize C++ adds overhead. I'll probably learn the native
> instruction set (I'm a curious person) but I use C++ day in and day
> out (I write simulations) so I like to fall back on what I know. So
> I'd imagine with the overhead c++ might add, I may need a bit more
> space.
>
> I looked at some of the suggested boards and they look neat. Most of
> them however only had 2 motor ports, I'd need at least four. I can
> build an H-bridge, etc.
>
   Wouldn't be that difficult to use an AVR with 4 PWM channels and add 
your own motor ports.

>
> Again, correct me if I'm wrong, but a minimalist "starter kit" could
> be had with just a few AVR's, a ISP programmer and some voltage
> regulators, correct?
>

    Corrrect, except that you don't need an expensive programmer at that 
level.   You can use a parallel
port (assuming your PC has one), and a 4 wire cable, wired to a piece of 
perfboard, or to pins that can
\be pligged into your solderless breadboard, for programming.  Dead simple.

> Could someone please contrast the Dragon vs. the STK500? It looks like
> the dragon is very minimalist (no cables or sockets) but can do
> emulation and 32kb of debugging, whereas the STK500 is more
> feature-rich with LED's and breakout board but no debugging
> capabilities.
>
   The STK-500 is a development board.   It has numerous sockets, which 
can be used to experiement with any AVR that comesin a DIP package 
(except the new 14 pin DIP packaged parts).  It plrovides on board 
button switches and LEDs for simple experimentation, and breakout 
headers for more complex experiemnts needing off-board circuitry.   It 
is about $80 (US).

  The AVR Dragon has no sockets at all, but is mostly used in a 
generalized way by soldering in a 40 pin ZIF socket, which allows *ANY*  
DIP packaged AVR to be used in the board.  The connections fort the 
programming, debug andf power pons is all taken care of by jumper wires 
between headers (you must provide the jumper wires, and you solder the 
headers into place, as well)   IT will program *ANY* DIP packaged AVR 
processor.   It will suipport JTAG or DebugWire debugging of AVRs so 
equiped, with up to 32 K of program FLASH.   While it is entirely 
possible for a 4 motor robot to require more than 32 K of control code, 
it is going to take you some time to get  to that point.   At which 
point, you may find you need to acquire one of the more expensive JTAG 
ICE II, devices, or a low cost clone of same.  Or,m you may decide to 
separate out control functions, and use multiple processors, in which 
case 32K of control Flash per processor may not be a problem for you.

   The AVR Dragon currently sells for $52, IIRC.


avrFreak