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DRV8711EVM: Tracking a 'home position' while motor is in operation

Griffin Peterson
Prodigy 40 points
Part Number: DRV8711EVM
Other Parts Discussed in Thread: DRV8711, DRV8825, DRV8825EVM

Hello,

I am looking to purchase a stepper motor and controller with adjustable speed and capable of tracking the passing of a home position. I am interested if there is a signal output on the DRV8711EVM that is capable of indicating the passing of the 45 deg home position the motor resets to on power up and reset.

I am optimistic there is a means of tapping into pins AOUT1,2 and BOUT1,2 on the EVM to derive the currents AOUT and BOUT and track when they will both equal 71% of their full value - Is this possible?

If not, are there any motor controllers you would recommend?

Thank you!

-Griffin Peterson

  • 0
    TI__Guru** 114905 points
    Hi Griffin,

    The DRV8711 does not have this ability. The firmware can be used to track the steps issued to determine the home position.

    Please look at the DRV8825. This device has integrated FETs and a home position indicator.
  • 0 in reply to Rick Duncan
    Prodigy 40 points

    Rick Duncan said:
    Hi Griffin,

    The DRV8711 does not have this ability. The firmware can be used to track the steps issued to determine the home position.

    Please look at the DRV8825. This device has integrated FETs and a home position indicator.

    Thank you for the quick reply Rick!

    I'm really searching for an evaluation model - I found the DRV8825EVM, but I cannot find reference to accessing the DRV8825's nHome output via the module. Is it only possible to read that signal with just the DRV8825, or is the nHome output reachable on the DRV8825EVM but is just not shown in the user guide because that pin is not on the other DRV88XX models?

    One more question - the DRV8825 datasheet says nHome's behavior is "Logic low when at home state of step table". Does nHome go low on EVERY pass through the home position, or just when the motor is reset and still in the home position?

    Thank you again!

  • 0 in reply to Griffin Peterson
    TI__Guru** 114905 points
    Hi Griffin,

    The nHOME pin is connected from the DRV8825 to the mcu on the EVM, but the firmware does not monitor the signal.

    The nHOME output is asserted every time the device passes through the home position.