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DRV8899-Q1: About SPI control

yuki.ando
Prodigy 100 points
Part Number: DRV8899-Q1

Tool/software:

Hello, Team.

I want to use the motor with SPI control in DRV8899.
Do I need to use the CTRL3 register?
Do I need to send the value 0xF9 or 0x79 depending on the direction that triggers the move?

Best regards.

  • 0
    TI__Genius 11651 points

    Hello,

    Thanks for your question.

    Our expert will look into the question and provide a response.

    Thanks,

    Ibinu

  • 0
    Prodigy 100 points

    Excuse me, may I ask you another question?

    Is it necessary to determine the direction of rotation using STEP and DIR when moving the motor with SPI?
    Is it possible to drive SPI without using STEP and DIR pins?

  • 0 in reply to yuki.ando
    TI__Mastermind 44245 points

    Hello Ando-san,

    yuki.ando said:
    I want to use the motor with SPI control in DRV8899.
    Do I need to use the CTRL3 register?

    Yes this is correct. For controlling STEP and DIR using this SPI register you must have SPI_DIR and SPI_STEP set to 1b.

    yuki.ando said:
    Do I need to send the value 0xF9 or 0x79 depending on the direction that triggers the move?

    Yes, correct.

    yuki.ando said:
    Is it necessary to determine the direction of rotation using STEP and DIR when moving the motor with SPI?

    This is not a requirement for the IC. However this may depend on how you write the code. If you are writing 0xF9 or 0x79 you will be writing the entire register with the desired value so it is not needed to know what the previous setting was. If you want to know the settings you can read the register.

    yuki.ando said:
    Is it possible to drive SPI without using STEP and DIR pins?

    Yes, this is the intent of providing this function. While using this approach the STEP and DIR pin inputs are ignored, they can be left floating or connected to GND. Please also note the motor moves by one step every time you set STEP bit to 1b. This bit will be self-cleared automatically after the indexer moves by one step - as mentioned in the register description in the datasheet. 

    Thank you.

    Regards, Murugavel