[L6470] The number of steps when the step mode changed automatically

[hori]

Posted on July 24, 2014 at 09:13

Hello, my apologies in advance for the newbie question.

I want to control stepping motor by using L6470.

And I want to know the current position (and current number of rotations) of the motor.

The ABS_POS register is contains the current motor absolute position in agreement with the selected step mode.

When the step mode can change automatically from microstep to full-step depending on the FS_SPD register, is the value at ABS_POS register enable?

If not, are there any other way to know the current position (=number of steps)?

Thank you. 

#l6470

[Enrico Poli]

Posted on August 21, 2014 at 14:20

Hello,

When the device switches automatically between microstepping and full-step the ABS_POS register still represent the motor position using the microstepping resolution. No operation is required by the user.

In any case, please consider that the voltage mode driving is not suitablo for full-step operation. I strongly suggest setting the FS_SPD parameter above the maximum speed value in order to always operate in microstep mode.

Regards

Enrico

[hori]

Posted on August 27, 2014 at 02:01

Hello,

Thank you for your response.

I was relieved to hear that ABS_POS has a constant resolution.

> In any case, please consider that the voltage mode driving is not suitablo for full-step operation.

I'm sorry. I couldn't understand this sentence. Excuse me, but could you tell me about ''the voltage mode''?

Best regards,

H.Hori

[Enrico Poli]

Posted on September 22, 2014 at 09:02

The voltage mode is the driving method used by the L6470 for controlling the phase currents of the stepper motor. It is a ST patented method specifically designed for the microstepping operation, so it does not give optimal results whe full-step is used.

If you are interested on more details, you can read the application note

AN4144.

 

Regadrs

Enrico

[hori]

Posted on November 11, 2014 at 08:41

Hello,

Please accept my apologies for the delay in responding.

Thank you for your in-depth explanation.

I understood the meaning of the following sentence,

> In any case, please consider that the voltage mode driving is not suitable for full-step operation.

So, I'll use microstep operation in any case.

Thank you very much.

Best regards,

H.Hori