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drv8824 motor direction

matic kres
Prodigy 20 points
Other Parts Discussed in Thread: DRV8824

I have a problem with my stepper motor direction becouse motor always spins in the same direction when dir is high or low. drv8824 is connected directly on computer thru LPT pin6(step) and pin7(dir) i check it and dir output is low(0.12V) high(4.95V).  VMA and VMB are 12V VCP is 22V V3P3OUT is 3.3V motor outputs are connected to the steper motor with 4 wires (red yellow orange and light brown). otherwise motor works well but it spins in the same way. Please help me :)

  • 0
    TI__Expert 7455 points

    Hi Matic,

    Does this happens in more than one board?

    I would check to see if the DIR pin is correctly soldered and receiving the signal command. Changing the state on the DIR pin should change the stepper motor rotation, if the motor has been wired correctly from the device.

    If you find that in fact the DRV8824 device is getting the correct polarity at the DIR pin, I would then try with a second device. Perhaps the first device was adversely affected during the soldering process. This is quite rare but a possibility we must look into.

    Hope the info helps. Best regards,

    Jose Quinones

  • 0 in reply to Jose Quinones
    Prodigy 20 points

     actualy have only one board at the moment becouse it is a test board and dir pin is correctly soldered becouse i check it directly from the top of the pin and it is changing signal.I also mesure out pins from Aout1 and Bout1 with oscilloscope and signal from Bout1 is allways ahead Aout1 no matter if dir is at 5V or 0V.

    Maybe there is a problem becouse sense resistors are not the same value Ra is 3.3ohm and Rb is 2,5ohm but i tryed and switch them but motor is still spinning in the same direction as before.

    i will make new board and be more carefull with soldering and hope for good results.

    Matic Kres

  • 0 in reply to matic kres
    TI__Expert 7455 points

    Hi Matic,

    The different SENSE resistors should not cause the stepper to move in the same direction regardless of the DIR input. It will definitely cause some major torque ripple due to different sine wave shape magnitudes. But if you see the phase relationship unchanging, then clearly the motor is doing what it is told.

    If the DIR pin is receiving the signal, then there must be something wrong with the device. Keep us posted on what you see with the second device.

    Best regards,

    Jose Quinones