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DRV8805 EVM STEPS pin output issue

Attila Szabo24
Prodigy 30 points
Other Parts Discussed in Thread: DRV8805

Hi

I am using the DRV8805 EVM which contains the DRV8805 driver.

With a unipolar 12V stepper motor connected I wasn't able to get the motor to turn. All the pins had correct outputs when measured with a scope. The problem was the STEPS pin. I had COM port connected, Motor enabled and then proceeded to try to start stepping the motor. The STEPS pin showed a high signal on the software but when I measured the STEPS pin the voltage was stuck at logic Low?

What is causing this issue?

-Attila

  • 0
    TI__Guru** 114905 points
    Hi Attila,

    Is this a new EVM or has been previously used?

    Please double check the R8 through R11 settings to confirm the EVM is configured for the DRV8805.

    If it is not, this can be corrected by selecting the DRV8805 tab and clicking "Configure Device"
  • 0 in reply to Rick Duncan
    Prodigy 30 points
    So the resistor settings seemed to have fixed the STEPS output. Another problem that is still the same as before is there is nothing being output on OUT1-4. Could this be a faulty driver? What could be causing this?

    Thanks
  • 0 in reply to Attila Szabo24
    TI__Guru** 114905 points
    Hi Attila,

    Not knowing the history of the board, it could be a faulty driver. Can you:

    1) Disconnect the motor and connect a pullup resistor (10k should do) to VM at each output
    2) Run the motor and provide scope captures of the step pin with respect to OUT1/OUT2/OUT3 and then step with respect to OUT1/OUT2/OUT4
    3) If any outputs are toggling, the inputs are probably correct.
    4) If no outputs are toggling, please provide the voltages at each input and the nFAULT pin
  • 0 in reply to Rick Duncan
    Prodigy 30 points
    This verified that OUT1-4 pins were working meaning the IC driver was fine. The motor still wasn't moving so I applied 12V manually to the coils and they moved. The problem ended up being the common on the coils was labeled as common ground instead of 12V leading to the whole confusion.

    Thanks Rick
  • 0 in reply to Attila Szabo24
    TI__Guru** 114905 points
    Hi Attila,

    Thanks for letting us know your issue. We hope others can learn from this.

    Good luck with the evaluation.