Newbie issues with Little Step-U Stepper Motor controller

EEder

I'm using a Little Step-U / Stepper Motor to do some very basic functionality. On top of the motor, I have a little plastic head with a distinct front and back.

I'm having a really hard time rotating the motor with any consistency and I can't seem to figure out why. I've read up on the documentation, which seems very good, but I still can't seem to get it working.

My problem is that the rotations seem to be inconsistent. Even something as simple as rotating in one complete circle consistently doesn't seem to work. I can't seem to figure out how the number in the command I send to the Little Step-U correstponds to the ticks on the stepper motor.

At times, a rotate in one direction will start with a quick, single tick jump in the opposite direction; then the the rotation in the appropriate direction.

for example,

 'baud is set to the correct baud rate, 3 is the appropriate pin
 SEROUT 3,baud,[noparse][[/noparse]"{E22,10}"]     

will rotate the motor in a full circle some of the time. If I execute that once, the little head will rotate in a full circle (usually, if it doesn't jump in the opposite direction first).

Supposing that it rotated in one complete circle, thats great. Then, if I execute the same command again, the rotation will not fully rotate - it will usually fall short.

I have tried using the {Q} command to set the position to HOME, but that doesn't seem to work.

I apologize for the lack of structure in this post, but my structured attempts to figure out what exactly is going on havent yielded any consistent results. I guess I'm wondering...

1) What do the numbers in the E and D commands mean? How many are in one full rotation?
2) Why would the stepper hop a tick inn the opposite direction before a rotation?
3) Any other explination for whats going on?

Thanks in advance for ANY HELP/EXPERIENCE shared, its much appreciated. [noparse]:)[/noparse]

-Brad

Larry

I don't know anything about the Little Step-U, but here are a couple hints.

It sounds like the single step in the wrong direction is the coils aligning· from a cold startup. generally, you need to have some sort of alignment routine (move to a limit switch) then do the work you want to do, Keeping the coils energized so they don't drift out of alignment..


You may be trying to move the stepper too fast. Torque with steppers is inversely proportional to speed. if you try to move too fast, the stepper can't keep up with the stepping pattern and you skip steps.

If the Little Step-U· allows it, try a stepping pattern that uses more than one set of coils at a time for more torque.

Larry

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔

allanlane5

And you have connected the grounds, right? Not having a common ground is a common error.

kelvin james

Howdy I have been using the lilstep for a while now. First of all, from what you describe it sounds like the coil sequence is out of whack. Could be you don't have the motor wired properly, the A +/-, and the B +/- must be connected properly for the motor to function properly. If you have some specs on the motor, could you post them? Also proper voltage is a concern to, you should be using a seperate power supply for the lilstep motor supply. So, if you can explain your wiring setup, it would help. Sounds like the stamp to lilstep is okay, otherwise it wouldn't do anything. I would highly advise going through the manual in detail, and fully understand how each command works, and how to use the multi-parameter commands. E is the command to move to a relative position in relation to what position the motor currently is, 22 is the amount of steps to move( you can use plus or minus here ), and 10 is the speed, as in steps per second.
You will have determine with simple math, the steps required to control the motor for full rotation, eg. if the step angle is 3.6 degrees, then 360 / 3.6 = 100 steps per full rotation. If you run in half step, the lilstep automatically converts it for you when using non-numeric positioning commands such as go to home or go to mark.Once you get it running, i would stay away from multi commands until you know how everything works. Something simple like this-

SEROUT pin, baud, [noparse][[/noparse]" {A50}"] Set speed at 50 steps per second, set it and forget it
SEROUT pin, baud, [noparse][[/noparse]" {D100}"] Moves the motor clockwise 1 full rotation
PAUSE 2000 Wait 2 sec
SEROUT pin, baud, [noparse][[/noparse]" {N}"] Motor moves to home or zero position
or SEROUT pin, baud, [noparse][[/noparse]" {D-100}"] will do the same thing.
Once you get accustomed to using different commands, you can start using variables from you stamp program to input different values, SEROUT pin,baud,[noparse][[/noparse]"{A",dec speed, "}"].
Once you get up and running, you can get it to do some pretty neat stuff.

kelvin

Also, if you are powering the motor with more than 5 volts, make sure you never accidently hook the supply up to any of the coil pins, or you will be tossing it in the garbage.