Starting with microcontrollers

[KONI]

I've always dreamed about building stuff, mechanical stuff, electric stuff...R2D2 Starwars podracer army of robots with laserguns ... STUFF!

Since I'm more of the programming type and less of the electronic type (I was always pretty bad in electronic), I thought I would try to do a project using a micro controller to build a Binary Clock. I know that you can do the exact same thing without any controller, entirely with an integrated circuit but since I'm planing on doing more advanced things, micro controllers are just what I want.

The problem is I don't know where to start. I have no idea what I need, what types of micro controllers there are and how I can program them. I am "of course" using google at this very moment and reading through a bunch of tutorials but I was wondering if some of you know some quality resources that cover in great detail, for absolute beginners, tutorials about creating something from scratch.

I don't think that I'll have any problems programming the controller, that's not what I'm worrying about. I'm having just slight problems figuring out how the micro controller is used to ... light an LED or make a motor move etc.

[rdrast]

Well, if you are looking for development hardware boards, take a look at Z-World stuff.

For excellent general purpose microcontrollers, look at this introduction to Microchip devices, and some of their MCU's.

[KONI]

I was hoping for an easy understandable tutorial about C programmable micro controllers, with a small guide about how to connect it to the components and install the IDE, compile and load it on the controller.

[Salem]

http://www.avrfreaks.net/

[Dave_Sinkula]

I was hoping for an easy understandable tutorial about C programmable micro controllers, with a small guide about how to connect it to the components and install the IDE, compile and load it on the controller.

I keep hoping for one too.

Off the top of my head, look for Dev Kits. Some families to consider are Atmel AVR, TI MSP430, Microchip PIC, some 8051 derivative, or even some of the old Motorola HC08 or HC12 chips.

I think I had the easiest startup with the MSP430 out of that bunch. And TI's documents are refreshingly done well in comparison to a number of vendors.

[RobR]

http://www.lpctools.com/index.asp?Pa...WPROD&ProdID=2 - about $59

Comes with a code-size limited evaluation version of Keil uVision IDE & compiler, along with a bunch of get-you-started projects.

http://www.8052.com is a good place to ask questions, and they have some good tutorials.

Signed an 8051 evangelist

[RobR]

Oh, and if you're new to embedded C - better get used to

void main ()

[Salem]

why?

[RobR]

What would you return the int to?

[Salem]

Why do you think you have a main() at all?

Yes, I am being pedantic.

[RobR]

I have no idea. It was a tongue-in-cheek comment. I do all my micro programming in assembler, not C. However, most C 8051 code I've ever looked at uses void main(), and I've always figured it's because

a) there's no OS to return anything to (which I've always been told is why we use int main() )

b) effectively an embedded application never terminates, so when would you return anything anyway.

Tell you what, enlighten me. Why would you use int main() in an embedded app? I'm genuinely interested by the way, not trying to be an ass (OK, maybe I was in the original post ).

Also, maybe we should continue this in a seperate thread so as not to derail the OP's.

[Dave_Sinkula]

In some TI DSP stuff I was once working with, your actual code did not start until main returned.

[RobR]

In some TI DSP stuff I was once working with, your actual code did not start until main returned.

Surely that's just semantics though? Main by a different name? I'm a bit out of my depth here, by the way.

[Dave_Sinkula]

No. AFAIR DSP/BIOS ran after main was finished. It was more or less the system initialization. You set up the registers, etc. in main, and after it returned things ran. It was actually rather cool.

[Salem]

Embedded platforms usually fall into the "freestanding" category.

5.1.2.1 Freestanding environment
1 In a freestanding environment (in which C program execution may take place without any
benefit of an operating system), the name and type of the function called at program
startup are implementation-defined. Any library facilities available to a freestanding
program, other than the minimal set required by clause 4, are implementation-defined.
2 The effect of program termination in a freestanding environment is implementation-defined.

Essentially, all bets are off as to what you name the first function, what parameters it takes and what it returns, should it return at all.

You have to RTM to find out what is needed for the environment in which you're working.

If you're genuinely working without an OS, then main is probably the thing which gets called, which loops forever, and returns void.
If you have an RTOS present, there could be many tasks, none of which are called main, but they do loop forever and return void.

> Why would you use int main() in an embedded app?
Hypothetically speaking, taking Dave Sinkula's example, one could imagine a scenario which determines if initialisation was successful or not.

But you're right, the vast majority of such embedded 'task' functions loop forever and return void.