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DRV8462: Motor driver microstepping position holding

Yonatan Zohar
Prodigy 20 points
Part Number: DRV8462

Hello,

I would like to use the DRV8462 driver for a stepper motor with a step angle of 7.5 degrees and be able to hold its position using microstepping, for example, keeping the motor at 10 degrees.

Is it possible to achieve this with this driver?

and if so how?

  • 0
    TI__Mastermind 29935 points

    Hello Yonatan,

    Like most stepper drivers microsteps are generate as even multiples of intermediate steps which is based on the magnetic poles behavior of the stepper motor. Hence the available microstep modes in the DRV8462 are full-step 1, half-step 2, 4, 8, 16, 32, 64, 128 and 256. At 256 microsteps, the stepper is expected to have a angular movement resolution of 7.5/256 degrees. Based on this, at this finest possible resolution setting if you move the stepper 341 usteps (in 256 microstep mode) the motor would have spun by 341 * (7.5/256) = 9.99 degrees. Moving 342 usteps would get you 10.02 degrees..

    Note this accuracy also depends on the construction accuracy of the stepper motor such as the precision of its poles spacing throughout the 360 degrees of the rotor and stator machining. Some error is expected even with a most expensive stepper. Also note when in microstep mode, depending on which microstep you'll be holding the holding torque would vary. The current waveform would be a sine wave and if you stop closer to zero the torque would be very low and likely result in motor shaft overpowered by the load torque. I hope this helps.

    Regards, Murugavel     

  • 0 in reply to Murugavel4637
    Prodigy 20 points

    Thanks for the answer!

    Yet I still can not figure how to config the device to stop and hold position at micro-step,

    by going over the data sheet I see that after the device receives a step rising/falling edge the device will stop after finishing a full step

  • 0 in reply to Yonatan Zohar
    TI__Mastermind 29935 points

    Hi Yonatan,

    That's correct. After every rising/falling edge the device will move and stop a step which could be a microstep or full-step depending on the microstep configuration settings. As well as every step rising/edge the indexer will advance by a step, again a microstep or full-step depending on the microstep settings.

    Regards, Murugavel