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perform single step with DRV8823

Stefano Checconi
Prodigy 20 points
Other Parts Discussed in Thread: DRV8823, DRV8821

Hello,

I want to use a DRV8823 stepper driver, but I also need to perform a single step.

In the datasheet i saw that this device has a register's bit to enable the motor, but I dont understand how can surely control the number of step to perform.

Can someone tels me if this is possible?

Thanks.

  • 0
    TI__Mastermind 26065 points

    Hi Stefano

    You can achieve one step on DRV8823 with no doubt.

    Let me give you some clue. Take AB as an example, here is cycle of 4 full step pattern.

    Step 1: APH 1, AEN 1, BPH x, BEN 0

    Step 2: APH x, AEN 0, BPH 1, BEN 1

    Step 3: APH 0, AEN 1, BPH x, BEN 0

    Step 4: APH x, AEN 0, BPH 0, BEN 1

    So the repeat of the 4 pattern 1,2,3,4,1,2,3,4.... makes your motor running in full step. Then if you want to go 1 step, just advance you pattern forword or backword once.

    Also you can achieve half step with 8 pattern. This is very basic for stepper motor driving. You can do some search on google.

    Thanks.

     

     

  • 0 in reply to Wilson Zuo
    Prodigy 20 points

    So I need a continous SPI data flow into that driver to move my motor?

  • 0 in reply to Stefano Checconi
    TI__Mastermind 26065 points

    Hi Stefano

    Yes. DRV8823 can only use SPI data flow to control. Every time you want the driver action, you give the SPI data.

    DRV8821 can be controlled directly by GPIO.

    Thanks.

  • 0 in reply to Wilson Zuo
    Prodigy 20 points

    Hi,


    I'm Roberto...

    I try the sequence you suggest above and SURPRISE (for me !) it works !

    The only thing I don't understand is during:

    STEP1 the AOUT1 run at 50Khz, AOUT2, BOUT1, BOUT2 stopped

    STEP2 the BOUT1 run at 50Khz, AOUT1, AOUT2, BOUT2 stopped

    STEP3 the AOUT2 run at 50Khz, AOUT1, BOUT1, BOUT2 stopped

    STEP4 the BOUT2 run at 50Khz, AOUT1, AOUT2, BOUT1 stopped

    It's a correct functionality ?

    Thank's

  • 0 in reply to Roberto Giannessi
    TI__Mastermind 26065 points

    Hi Roberto

    Yes. The 50KHz you see is the internal PWM current regulation. 

    When you say the other three outputs are stopped, it is partly correct. There should be another one output is on but just no switching.

    The sequence here is called 1-phase energizing full step driving. You can also find a two phases energizing full steping method. And you will get all the outputs on all the time in this scheme.

    Best regards,

  • 0 in reply to Wilson Zuo
    Prodigy 20 points

    Hi,


    thank you for quickly replay,


    What are advantages choosing a solution instead the other ?

    Regards, Roberto Giannessi