how to drive a stepper motor without using stepper driver?. I know that stepper motor can be driven using pulse width modulation and it can be achieved by using port pins. what are all the other requirements we have to consider?(timer channel...)
There's no way anyone's going to be able to reply to this. It's far too dependent on too many variables. Usually your application will drive the selection of a type of stepper motor. This will further leads to selecting a control scheme (half-stepping, microstepping, etc). And the design of an actual hardware interface to do this involves a myriad of variables. Entire books have been written about the subject and you should select and read a few of those.
I know that stepper motor can be driven using pulse width modulation Then, you better get rid of what you know. Erik
Actually, using a PWM to generate a sine wave for microstepping is one of the smoothest ways of controlling a stepper with a uC, so he'd do well to hang onto that. That is, assuming that's what he meant.
Stepping with sine?? never heard of that, but then I have not done any stepping motor drive in EMI sensitive apps. Erik
Erik, It has nothing to do with EMI. Sine waves are the theoretical ideal method of stepper control. With two properly phased sines, the motor transitions smoothly from one pole to the next rather than "stepping" as in a standard driver. Refer to the following page: http://www.stepperworld.com/Tutorials/MicroTutor.htm If you take their DAC input and just replace it with a PWM / filter, you can get a uC very close to generating these ideal signals.
well, I learned something todat, thanks. I have driven steppers with up to 50kHz on squares, next time, if there is one, I'll consider sines. Erik
Nice article; thanks for posting the link.
As Jay said, sine waves are only ideal in theory. In practice the motor will not turn smoothly. Yes, it is possible to make the motor run smoother by applying a current waveform to the windings, but the optimal waveform is not sine, and depends on the motor characteristics. The usefulness of microstepping depends on the application. It is at it's best at low stepping rates. You may also gain some positioning accuracy, but that will not increase in the same ratio as you increase the microsteps.
Yes, there are of course some significant differences between the theory and practice of things. Mechanical properties of the system connected to the motor as well as imperfections in the motor's construction, etc. make driving it with a perfect sine wave less than possible. But using 1/8th stepping, say, instead of full or half stepping can give some dramatically increased smoothness, increased positional accuracy, and decreased torque ripple if done properly.