Micro Stepping mode

[itsmejatinus]

Posted on March 17, 2004 at 10:06

Micro Stepping mode

[itsmejatinus]

Posted on May 17, 2011 at 10:17

Hello,

I want to drive the stepper motor with ST micro. The maximum operating current for stepper motor is 20mA. Can the stepper motor be driven directly by using PWM waveform from micro without the need of any stepper motor driver/current driver? I want to use the motor in microstepping mode. The port current driving capability is ~25mA. For microstepping, is it mandatory to have a current driver like L6208 or L298. Thanks

[gaetano]

Posted on May 17, 2011 at 10:17

Hello,

generally for the microstepping you use an additional microcontroller with PWMs to drive the L6208 to provide the sinusoidal current level profiles. In your case from a theoretical point of view it seems possible to use the micro itself to manage all the operations generally performed by the drivers you mentioned. Open discussions on how to manage the sensig resistor to implement the constant current control necessary for the microstepping mode. I would try! Best regards, Tanio

[gaetano]

Posted on May 17, 2011 at 10:17

To provide the microstepper driving it is mandatory a constant current control.So, you put a sense resistor to read the motor current and then compare it with a reference.

The reference is a value kept from a look-table that reproduces a sinewave profile. According with the topology you will intend to use the sensed signal will be conditioned (amplified & filtered) with OP AMPs and, then, read by means the MCU AD converter. The duty cycle of the PWM will be function of the current reference level you wnat to reach. The logic on how to generate the right levels of current refernce to produce a microstep rotation is simple but not immediate. I will send you a document that explains in great details an application example on microstep driving. It could be considered as a good starting point for your needs. Regards, Tanio

[itsmejatinus]

Posted on May 17, 2011 at 10:17

Thanks to provide the microstepping document.

[itsmejatinus]

Posted on May 17, 2011 at 10:17

Thanks for the information.

Could you also info about what external circuitary would be required for current regulation using PWM? I would also like to know how to adjust the PWM duty cycle in order to provide the required current for each microstep. My stepper motor has 24 microsteps per rotor revolution. Do i have to generate the one complete sinusoidal waveform per rotor revolution(i.e 24 microsteps) or do i have to generate half sinusoidal ? For your information the motor has 2 full steps per rotor revolution?

[itsmejatinus]

Posted on May 17, 2011 at 10:17

Have you sent me the document?

[gaetano]

Posted on May 17, 2011 at 10:17

Please, let me know your e-mail address where I can contact you for further details.

Regards, Tanio

[itsmejatinus]

Posted on May 17, 2011 at 10:17

My mail address is-

itsmejatinus@indiatimes.com thanks.