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Stepper Motor Control

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catceefer:
I wonder whether anyone can help? I have never had anything to do with stepper motors and would appreciate some basic guidance or link to an idiot's guide. I have been looking at the motors on e-bay and see that some come with a control board, others do not. My questions are:

- do I need a board?
- if I use a board, how do I programme it?
- if I use a Raspberry Pi or Arduino, do I need the board still?

To put the question into context, I wish to use the motor to move a lever forwards and backwards a set amount every minute.

All really basic questions, I know, but I need to start somewhere.

Thank you.

James.

Will_D:
Stepper motors usually need to separate boards (Ok they can be built as one)

The first board is the motor driver board. It drives the motor's coils "as required" (see next point) . It requires a high capacity power source like 12v at 2amps all the way up for very big (48V at 10 amps) steppers. It contains some large semi conductors that may need heat sinks.

The second board supplies the "As required" information. This supplies the driver board with digital (usually 5v) signals: Pulse, Direction, Enable. These signals are generated either by a simple board (like a simple speed controller (pot) and direction (switch)).

However most boards are some form of process control computer like the Arduino or some other PIC/PLC set-up.

Then you "just" write the software to do what you want. 

vtsteam:
I 'm sure you can look up "stepper motor" on the internet and get a better and more in depth definition than we can provide here. What it seems you are asking is what do you need for gear to fit a specific application. As in any practical engineering question, the specifics of what you want to do will decide what you need to achieve it.

A lever moving back and forth a set amount every minute is so vague that there is no answer. How much force is required? How much distance must it move? Is the movement periodic, uninterrupted, and independent of circumstance?

The answer could easily be that you don't need a stepper motor and computer and drive circuitry at all, you need a motor and a timer, or a solenoid and a timer, or even just a synchronous motor and linkage. Any of the above could be the size of a few gram pager motor, or weigh hundreds of kg. depending on what lever you're talking about.

In other words, it's important to have clear in mind what you want to do first in specifics, before researching the means to do it. If you start out just choosing a means, you'll make finding a good solution hard for yourself. The great attraction of the internet is an exposure to advances in affordable cutting edge digital technology. The big problem is thinking therefore that it is the the only way, or even the best way to achieve a simple result.

If you said for instance,I'd like to wave the wing of a copper garden dragon weighing 2 pounds about 3 inches once a minute, somebody here might say, try this timer and this windshield wiper motor and this speed reducer, etc... :beer:

catceefer:
Looking back, it was a badly phrased question: I should not have rushed it.

A little more detail. I am very much at the planning stage, but am doing some drawings for a clock with some animated figures. Rather than using springs or weights to drive the clock mechanism, I am looking at a version of this lever-operated escapement https://www.youtube.com/watch?v=hnko9fZRO-w.  I plan to modify it a little by adding a long bar and having a figure pull the lever to drive the clock.

The design as shown uses a solenoid, but this will give a very abrubt movement. I want something a little more controlled so that the figure can be seen moving. I have considered a number of ways to do this, but felt that a stepper motor would be the most controllable. However, I can see how a radio control-type servo may work. Any suggestions would be welcome.

The copper dragon is still ongoing, the clock being planned for its completion. I have made the parts for an oxy-propane torch, as raised in an earlier post, but as waiting for my brazing kit to be returned from a loan so that I can assemble it.

Regards,

James.

raynerd:
Catceefer - I've done a few projects with steppers and Arduinos now so can hopefully help a little. In a basic sense, the stepper motor driver (or board as you call it) detects pulses along the pulse line and steps the motor by a certain rotation each pulse. There is also a direction line, pull this line high to rotate the stepper one way and low the other.

You would need your Arduino to pulse high and low and high and low for the direction and still need a driver to detect the pulses and run the motor. You can build drivers but for the cheap price of something like a tb6540(?? Forgot the number??) I never thought it was worth the hassle.


You could get it running with very little code. In lay code..

If buttonDirection   #So keep direction button pressed to go one way, release for the other way
Pin 1 = 1
Else             /pin 1 connected to direction. High one way, low the other way
Pin 1 = o

While (step button pressed) #start moving!!
Loop 10 times #this isn't code, you'd need to do a count
Pin 2 = 1
Delay (10)    #pin 2 is connected to the pulse on the driver and just goes high low ten times - motor moved 10 steps
Pin 2 = 0


That's just a load of nonsense code but you get the idea. Best to out the steps in an interrupt but the delay works, for definate, because I have done it.

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