I posted this on a few sites so I figured why not post it here.
I got the sparkfun stepper motor and rigged it up to be %100 serial controlled using an arduino and an easy driver.
See this link for more info
http://forum.sparkfun.com/viewtopic.php?p=77326#77326
I am uploading a youtube video which will be only later today lol its 4am here ha ha been up all night programming so when I wake up I will post the link as the video takes some time to process on youtube.
Here is the youtube link, it processed way faster than I thought it would.
HQ video isn’t available yet and it may not work right away but in a few hours everything should work just fine!
UPDATE
I am making another video, after someone commented on asking how speed could be controlled I was in shock that I forgot speed control lol. How do I forget things like this
I won’t go into to much depth it will be a quick video showing the new feature!
DOWNLOAD THE CODE HERE
http://code.google.com/p/stepperserialcontrol/downloads/list
Cool stuff, I have all of these components so I will attempt your code.
I’m looking forward to duty cycle control and frequency control if possible.
The frequency at which you step the easy driver is controlled by the microsecond delay. The faster you step it the faster the driver goes.
Duty cycle is 100% the motor is ALWAYS on that’s the problem with the v3 driver, the v4 will breakout the pins on the driver to allow you to turn off the current when the motor is not in use.
As I said before I was in the process of putting speed control in so the code in those forums is outdated, this link has all of the final code in text file just copy and paste it into arduino.
http://code.google.com/p/stepperserialcontrol/downloads/list
The new youtube video is up if you guys would like to see it.
[Sparkfun stepper motor and easy driver v3 serial control - YouTube
This is compatible with vex, all you have to do is turn the direction pin either on or off for forward or backward and then pulse the step pin every few hundred microseconds.
Does anyone know if the vex can do such small delays? I don’t remember a microsecond delay option in easy C v2 or Pro but I could be wrong. MPLAB can do it I know that but I’m not sure if easy C does it.](Sparkfun stepper motor and easy driver v3 serial control - YouTube)
I am really interested in finding out the torque of that stepper.
I know that the stepper torque varies with voltage applied, but how does the stepper react to you trying to stop it from spinning at full speed and lets say 12V. (or whatever you have hooked up)
The reason I ask is because i’m considering using 2 of these steppers as drive motors and I am wondering if they are up to the job. (basically their like DC motors with stepper encoders built in which is great!)
Thank you
Technic-R-C
Stepper motors are not simply DC motors with encoders. They are very special motors with multiple coils inside. The shaft is magnetic and the center chunk looks almost like a very fine gear. When the coils are switched on and off in a very specific series you can advance that gear like center one tooth forward or back. The higher the voltage the faster it will advance a tooth but the faster you step it the faster the motor spin’s. If you step it to fast though and the voltage is to low the motor will stall so voltage is very important.
Here is a link to a website and a video on how they work.
http://bits.me.berkeley.edu/mmcs/PROPRNT2/STEPPER.HTM
[http://bits.me.berkeley.edu/mmcs/PROPRNT2/MOVIES/STEPPER.MOV
The rated torque of this motor is 2.4kg/cm holding at 15.4v.
Now as for stopping the motor at full speed you can stop it immediately and precisely at a very specific location. There are 1600 microsteps per revolution on this stepper motor which is actually 200 full steps 1.8 degrees per step.
These could be used as very precise driver motors but you would probably have to gear them for torque and somehow get the vex to pulse pins in the microsecond range if you use easy c v2 or pro.](http://bits.me.berkeley.edu/mmcs/PROPRNT2/MOVIES/STEPPER.MOV)
My SunBot uses two geared stepper motors and two Sparkfun Stepper Motor Controllers to control the Azimuth and Elevation drives that allow it to point a 12 Volt Solar Panel to a fraction of degree. The gears on the stepper motor gear box matched the Vex gears perfectly!
I am now working on the Vex Controller firmware to automatically point the solar panel to the Sun from any location on Earth or even indoors or in a deep cave. I recently added two Vex Quadrature Optical Encoders and an XYZ accelerometer which I plan to use for position feedback. The SunBot does not use multiple phototransistors or photocells (CDs) to find the brightest spot in the sky, instead it uses Astronomical methods.
You can see the SunBot’s Azimuth and Elevation stepper motor drives and SunBot mounted on my Gilbert IV Explorer using the following links:
https://vexforum.com/gallery/showimage.php?i=3571&catid=searchresults&searchid=335341
https://vexforum.com/gallery/browseimages.php?do=searchresults&searchid=335341
Good for you! I also am using the Sparkfun Stepper Motor Widgets for my Sunbot robot application shown in the VEX Gallery. I have been able to interface two stepper motors using the VEX Controller, and can now have Sunbot point a solar accurately panel in almost any direction.
I also posted some PIC18 C code in the gallery, showing how I sent commands to the Sparkfun Stepper Motor Controller Widget.
Sweet, a true sun tracking robot now this could come in handy. With the new v4 drivers from sparkfun you can turn current on/off to save power so using these to point a solar panel sounds really awesome. That way the robot only has to juice em up for a second to point the solar panel in the orientation in which it will produce the most power. You get loads more power when pointed directly at the sun instead of at an angle and power is important!
Check out the October 2010 issue of SERVO Magazine for a Stepper Motor article using the VEX Microcontroller.
http://bits.me.berkeley.edu/mmcs/PROPRNT2/MOVIES/STEPPER.MOV
The rated torque of this motor is 2.4kg/cm holding at 15.4v.
Now as for stopping the motor at full speed you can stop it immediately and precisely at a very specific location. There are 1600 microsteps per revolution on this stepper motor which is actually 200 full steps 1.8 degrees per step.
These could be used as very precise driver motors but you would probably have to gear them for torque and somehow get the vex to pulse pins in the microsecond range if you use easy c v2 or pro.
Check out the latest copy of SERVO (April 2011) with a VEX project (Sunbot III) featured in the front cover. It uses the VEX Microcontroller to drive two Sparkfun Easystepper motor controllers that are used to accurately point the solar panel at the Sun.
Robo,
I’m working on a project and could really use your help with the stepper motor.
Are you still here?
Calvin
What are your questions regarding stepper motors?