Little Step-U Motor controller

Spencer

I am interested in using the above motor controller to control a unipolar stepper motor off of my BS2. I was wondering if anyone has any experience
with this particular controller and how easy or difficult it is to set up and use. I am relatively new to the world of Basic Stamps, so please keep that in
mind when replying. Thanks.

Steve Joblin

The last few pages of the manual (you can download the pdf here --> http://www.parallax.com/detail.asp?product_id=27938) show how it hooks up to a BS2... looks straight forward enough... My sense is that being a noob (like me), the software side may be more challenging than the physical hook up. I am surprised that you haven't had a few posts to your question.... I was thinking about incorporating a stepper motor in my next project and would have asked the same question you did (so don't feel like you are the only one!).

I thought that one of the Stamps-In-Class curriculums covered the basics of stepper motors, but I couldn't seem to find it (albeit, I only looked for a quick minute).

Spencer

Thanks for the reply, Steve.· I only skimmed the manual partially yesterday, that's why·I missed it.· I guess next time I will
go the whole way through before posting.· If anyone has any sample code for this particular motor controller, other than the
short piece at the end of the manual, I would greatly appreciate that as well.· Thanks.

kelvin james

It seems i am one of the few that have actually used a lilstep, so here goes. It is easy to use with a stamp, and does everything that it says it can do. But, it depends on the application which determines whether it is right for your own purposes. Since it does operate by serial commands, there is some time lag, as opposed to a stepper controller ic wired directly to the stamp. For a little board it is pretty powerful, can take up to a 35 volts and 3 amp steppers. Has built-in ramping, position register, ability to power off coils, and a lot of other features. The coding is fairly simple, you just have to fully understand the way each serial command works, and you are off to the races. It can get a little tricky pulling positions from variables if you are new, but it is not rocket science. Another nice feature is the option to put in into slave mode, where the stepu controller is bypassed, and you can just pulse the motor dircetly from the stamp. Like i said before, it is very simple to get wired up and running, only a couple of connections to the stamp, if that is what you are looking for. If you can explain what you want to use it for, i can give you a better idea if it will do what you want.

kelvin

Spencer

Thanks for the reply, Kelvin. I was looking for something to control a pair of stepper motors on a robot chassis that I have. They are 3.15 V, 1 A per phase
unipolar steppers. Obviously, I would need two lilsteps to control the motors. Would controlling them simultaneously off of the two different controllers be an issue? Also, how much time lag are we talking? Is it really noticeable? Thanks for your help.

kelvin james

On the lag time thing, without getting into the mathematics, since the serial com is at 2400 the motor will not react instantly from a command from the stamp. But we are talking milliseconds here, so in your instance it probably would not be a big deal. If it were a time critical application, such as controlling 2 cnc axis simultaneously, it would be a problem. And the stamp will only be able to send one command at a time, but again, how fast does it really need to be? Getting info from the position register is a lengthy process, as a timeout is required for communication, so that won't happen on the fly. If you are looking to use steppers in robotics for positional accuracy, you have to make sure you don't have a stall situation that can arise, because the stepu will still think the motor is moving, and that tosses the positional accuracy out the window. And the only way to get around that is to have a positional shaft encoder, which kinda defeats the purpose of using a stepper in the first place. There are lots of step controllers out there, the stepu is probably the easiest to use with a stamp, especially on the code end.

kelvin