Smiley Micros and NerdKits ...

As a software guy, lurking on the periphery of the robotics hobby, I've taken a liking to AVR type processors, and I've decided to learn a bit
about hardware, circuits, control and such ...
In keeping, I recently shelled out to purchase a NerdKit, and quickly put together the tutorials based upon an AVR, some sensors, an LCD display, and a few caps, resistors, transistors and fets ... moreover, I used an ubuntu laptop to connect the USB port to an adapter on the chip, to program the thing in moments flat ... cool
Joe Pardue's Smiley Micros has been doing some tutorials in Nuts/Volts magazine (or is it Servo?), and has moved from the AVR Butterfly tutorials (for which he has a book and kit), to an Arduino Decimielia (sp?). I purchased his butterfly kit some time ago, and started playing with that recently as well ...
Between the two "kits", and tutorials, I'm beginning to get a handle on programming to the hw, which is different for someone used to having a whole OS, with API's and most of the hard stuff already done ...
My circuit design is still a bit at the elementary stages, but the little squiggles and lines you hardware men of mystery use for a language (circuit diagrams) are slowly becoming eerily familiar.
I must say, that using the NerdKits/Smiley approach to a gentle introduction to embedded stuff is a decent one, but I have a long way to go before I can achieve my goals ...
    1.) an ESC (speed control) circuit for hard drive BLDC motors.     2.) a multi-servo control circuit     3.) a Bluetooth enabled control board with MEMS      accelerometers/gyros ...
Basically, I want to ultimately create a UAV from salvaged hard drive motors ... and stuff lying around my junk drawers.
Clearly I have a long way to go, but having the knowledge to know that I have a long way to go is a good first step, and probably not enough knowlege to know how much work is involved ... (I think?).
As for now, ... one circuit at a time ... and the software to make it all work ... and carefully, so I don't let all the magic smoke out of the chips 8-) ...
Cheers, Rob Sciuk
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Just be sure that you have a handle on the basics of electricity. You may already have the issues of voltage, current, wattage, and the basic components of resister, capacitor, inductor, rectifier.
I would also add the transistor and LED as semiconductors that you need to get a good understanding of. Otherwise you may see a lot of "magic smoke" before you really understand what is going.
Joe Dunfee
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On Mon, 17 Aug 2009, l o wrote:

Thanks, Joe.
From my perspective, Ohm's law and such are pretty straightforward. Putting them to practice however, will very likely cost me a few components, but I'm trying to learn from others (and learning circuit diagrams seems the best approach for that). I'm reading Circuit Cellar, Nuts and Volts, Servo and Make magazine ... and while not *ALL* of it is clear, I'm beginning to see some headway.
Getting the idea of using resitors to limit current, diode's to protect circuitry and such is something I'm just now trying to get my head around. Pull-up/Pull-down, current limiters, amplifiers, transistors, bias resistors ... man, there is a lot to learn!!
As indicated, my goal is to create a *SIMPLE* (small/light) circuit to control BLDC's using a sensorless design ... ultimately to be able to tie together a PWM power control via MOSFET's to the BLDC ... but there exists a real mystery (in my mind anyways), at how to feed back the Back EMF from the dormant phases of the motor to the processor ... I'm thinking via an ADC, but I have to get the voltage/current scaled properly, and then apparently find the crossover point (0V -- but relative to what??) ... as in many things in life, timing is critical ... 8-)
Initially, I had thought that a couple of transistors might be used, but apparently startup is critical, owing to the current draw, and will have to be ramped up ...
I know that this project is perhaps over-reaching my abilities currently, but if I get to the point where it all makes sense, then I will have accomplished a fair bit ...
The funny thing is, programming the AVR's in C turns out to be the easiest part of the whole thing (and an absolute BLAST) ... but I suppose that's because I'm coming at this thing backwards ...
Cheers, Rob.
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I just realized that I did not make clear that the transistor, diode, and LED are a different sort of critter. Semicondutors don't behave the same as resistance loads. Also, it is starting to sound like you really are engineering a circuit, not just making minor adaptions to an existing design.
For that, nothing beats getting a text book and going through all of it so you can know you aren't missing and understanding of important stuff. It is the stuff you don't know about that makes the "magic smoke".
Joe Dunfee
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On Fri, 21 Aug 2009, l o wrote:

Perfectly clear, and darned good advice. I'm looking at an electronics book on analogue stuff, and will work through it. Thanks, Joe. As indicated, the processor/semi programming is the easy part. The tricky part is safely hooking it up to real devices ... and that's where I'm struggling.
Cheers, Rob.

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snipped-for-privacy@ControlQ.com wrote:

Something that would save you a mess of reading and probably some smoke would be to talk with someone who knows about this stuff as you go through the first few projects. Very little beats walking through a design with someone as a way to learn.
Good Luck, BobH
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BobH wrote:

If you live in an area with a robot club, I would recommend that you join. Since you are trying to figure out some electronics stuff, the local amateur radio club is another reasonable substitute.
-Wayne
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