L6470: Output resolution, no different between 1/128 and 1/32?

[michaelkroneberger9]

Posted on December 22, 2011 at 15:03

Hi

We have measured the output signals of the bridges in 1/128 and 1/32 step mode and we can’t see a different voltage resolution between these 2 modes (see attachment).

We have used the “GoToâ€�-command for the positioning, and mostly we can see a repositioning of the motor after the 4th step only in the 1/128-step mode (what  confirms with the measured values).

Is there any limitation of the output resolution?

Best Regards

Michael

[Enrico Poli]

Posted on January 10, 2012 at 10:35

Dear Mike,

the voltage resolution is limited by the integrated PWM modulator of the driver (8 bit).

Using low KVAL values (in attached example you are operating below 10% of the full range), the voltage difference between two next microsteps could be below the PWM modulator limit.

Kind Regards

Enrico

[michaelkroneberger9]

Posted on January 24, 2012 at 07:28

Hi Encrico,

Yes, meanwhile I came to the same result; I have calculated it, and it fits to the measuring values.

Is the maximum value (255) equal to 100% KVAL or is there any additional reserve?

Regards

Michael

[Enrico Poli]

Posted on January 25, 2012 at 14:10

Hi Michael,

the maximum value of KVAL il 100% that is equivalent to a sinewave with a peak value equal to VS. There's no way to obtain higher values.

Regards

Enrico