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DRV8889-Q1: STEP\DIR function using SPI Interface

Alpesh Borad
Intellectual 990 points
Part Number: DRV8889-Q1

Hello,

I am going to use DRV8889 in one of my upcoming project.

From Datasheet of DRV8889, I found that there is Control Input STEP, DIR used to control the Direction and Step of the Motor. There is SPI Interface is also available.

My Question is that : Can we use the SPI to manage the Function of STEP and DIR? If Yes then what should be the electrical condition of STEP and DIR Pins(Pull Down or Pull up)?

Regards,

Alpesh

  • 0
    TI__Guru** 114905 points
    Hi Alpesh,

    Yes, the SPI can control the STEP and DIR function by setting the SPI_STEP and SPI_DIR bits to 1. Writing to the STEP and DIR bits in the CTRL3 register will then control the stepping and direction. Please note the errata about the STEP bit in the current datasheet (date April 2019).

    The STEP and DIR input pins can be left floating or connected to GND. There is an internal pulldown in the device on these pins.

    Please note when using the SPI to control the STEP input, the firmware may have an impact. For example if the firmware is servicing an interrupt when the STEP bit is to be written, there could be some delay. This may have an undesired effect at higher microstepping speeds.

    Using the DIR bit of the CTRL3 register should be no problem because this bit is typically not time critical.