Stepper motors & controllers

[Tjalfe]

there are all sorts of USB to RS232 Converter cables out there, so getting an RS232 version should not be a problem

[az]

I know RS, but I have a lot of trouble navigating their site.

AZ

[spadnos]

I think you'll find that the hardest part of this is just getting a signal out of the PC.

There are driver chips available (cheap - like $3.00) that generate phase signals given step pulses. That may be a little too low level for you, unless you're into designing and soldering your own boards.

Actually, this may be the best solution for you. It's cheap, and has both the motor and driver. The only part left is the link between the PC and the board.

For that, you whould get either an ethernet or USB I/O adapter. Something like this would do. You'll need a power supply - a standard 9V DC wall transformer would do fine (for both the motor and the logic sections). Controlling it through software should be easy: you use the library supplied with the USB IO card, and just set one bit for direction, and toggle another bit for steps:

(in pseudo-C code )

#define DIR_BIT         0x01    // or whatever bit you connect it to
#define STEP_BIT        0x02    //  ditto

void do_steps(int number_of_steps, int direction)
{
        int i, d;

        if (direction) d=DIR_BIT;
        else d=0;
        for (i=0;i< number_of_steps;i++) {
                output_to_usb(d | STEP_BIT);    // set step bit and direction bit
                delay(1);                       // delay a millisecond or so
		output_to_usb(d)                // turn off step bit, leave direction the same
                delay(1);                       // delay again
        }                                       // repeat for the correct number of steps
}

If you need exactly 5 degree divisions, you'll probably need to use gearing to achieve that. Most steppers are either 1.8, 3.6, or 7.5 degrees/step.

Oh yeah - the USB power spec is 5V, 100mA for low power devices, 500mA for high power devices. I'm not sure that all laptops can properly supply high power devices.

- Steve

[degrub]

Dr Dobbs journal used to have articles on this sort of project. THere are a couple other rags on "real time" projects..My mmeory is failing me ....or is it the wine? Check out the electronic hobbyist section at a library...... or find an EE grad student !

Frank

[spadnos]

Originally posted by degrub
Dr Dobbs journal used to have articles on this sort of project. THere are a couple other rags on "real time" projects..My mmeory is failing me ....or is it the wine? Check out the electronic hobbyist section at a library...... or find an EE grad student !

Frank

Are you sure you're not thinking of "Circuit Cellar"? ( http://www.circuitcellar.com )

Dr. Dobb's is much more of a high-level software magazine, in general.

- Steve

[degrub]

...it was the wine.....of course you are correct.

Frank

[az]

We're now opting for building a controller/driver ourselves, I'm thinking of using the IO-Warrior to connect it to USB. Think this would work?

AZ

[degrub]

i'd query them specifically about your application. Looks like it is more for pushbuttons and leds. i'm guessing, but i think you would have to have a relay between that device and your stepper controller, unless the controller will take low voltage pulse trains as input directly.

Frank