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DRV8801

Mahendra Gunawardena
Expert 1780 points
Other Parts Discussed in Thread: DRV8801EVM, DRV8801

 

Overall Problem:

We have a need to drive a Bistable Rotary Solenoid to control a robot arm.

Components in the Solution:

1.      TI, DRV8801 motor driver (DRV8801EVM board)

2.      Atmel processor

3.      Bistable Rotary Solenoid

Overall Design

The goal is to drive the bistable rotary solenoid CW and CCW using a PWM signal. The Enable pin is supplied a with a PWM signal. Phase signal is use to control CW and CCW. For this experiment the mode1 and mode2 pins are 0 and 1 respectively.

  • Channel 1 - Out+
  • Channel 2 - Out-
  • Channel 3 - Enable (PWM signal)
  • Channel 4 - Phase

 

 In this scenario I am expecting Out- to have the compliment of the PMW signal seen on Out+. Base on the limited information I hope you can shed some light on the problem.

 

 

 

 

  • 0
    TI__Guru 54675 points

    Mahendra,

     

    I think a scope capture is missing from the post as I am not able to see it.  Can you re-attach the image as a JPEG or BMP?  

     

    Also, you mention an Atmel processor, but also mentioned you are using an EVM.  Did you try experimenting with the micro/software given with the kit before wiring in your signals from the Atmel processor?

     

     

  • 0 in reply to Ryan Kehr
    Expert 1780 points

    2275.DRV8801 Technical Support.doc

    Hello Ryan,

    I attached the complete file. I hope you can access this file.

     

    Best Regards

  • 0 in reply to Mahendra Gunawardena
    TI__Expert 7455 points

    Hi Mahendra,

    If you want to see the outputs opposing each other as you apply a PWM, the PWM must be applied to the PHASE input, not the ENABLE input. If you do this, you will be able to control the direction of actuation by going above or below 50% duty cycle.

    When you PWM the ENABLE input, the outputs only oppose each other during the fast decay portion. This is what you have configured the device to operate at, but the scope capture is set to 200 ms per division, which is too coarse. Current decay often takes microseconds so if you zoom in, you should be able to see the outputs switching accordingly for a few microseconds.

    Hope the info helps. Best regards,

    Jose Quinones

     

  • 0 in reply to Ryan Kehr
    Expert 1780 points

    Hello Ryan,

     

    When I got the EVM board it was modified internally within our company. I saw the board work. I don't have scope plots of the DRV8801 working using the TI micro MSP430 micro on the EVM. 

    In summary,

    • Pin 15 and 16 of R2 is isolated.
    • Pin 2 of U3 is isolated

     

    Thank you for your help.

     

    Best Regard

     

    Mahendra

     

  • 0 in reply to Jose Quinones
    Expert 1780 points

    Thank for the response. Let me try your suggestion.

     

    Best Regards

     

    Mahendra