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DRV8812 EVM PPS and Fixed number of steps control

Lambert Burton
Prodigy 10 points
Other Parts Discussed in Thread: DRV8812EVM, DRV8812, DRV8824

Hello,

I'm new to this forum and have a few questions.  I did search the forum and found some good information but none directly answering a couple of issues I've run into with my new DRV8812EVM.


1) I have the DRV8812 tab selected on the GUI.  It appears the Stepper Demo is the only means to rotate the motor shaft.  I would like to rotate a defined number of steps as in the DRV8824 tab.  Is this possible?  I read on a different post from May 2011 that a new version of the code would allow this.  Is the new version ready?  I assume it would include a new Windows app and MSP430 hex file.  I have the ability to reprogram the MSP430 over JTAG using the MSP-FET430UIF JTAG programmer so I could use a hex file to reprogram the MCU.

2) I've selected the Potentiometer control of the AVref and Bvref voltages via the board jumpers and want full step control.  When I program in a desired PPS into a 7.5 degree/step motor (48 steps per rotation) I am getting what looks like 12.5 PPS which is 1/8 the desired step rate.  Is this text box the PPS value when using the DAC Vref which is a sine output for microstepping (8x steps)?  If so than the text box entry is 8x the desired step rate when full stepping? 

 

Thanks,
Lambert

  • 0
    TI__Expert 7455 points

    This thread has been serviced directly with the customer, but for informational purposes:

    1) On the DRV8812 EVM, the software is rather rudimentary and only showcases the ability to microstep by modulating VREF. We are writing an application note in which all the other motion control parameters will be added in a standalone application.

    2) The demo is doing 16 degrees of microstepping by modulating VREF. If the ability to modulate VREF is removed from the micro (as by using the pots), all that is left is full steps.