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DRV8849: Step pins connect suooprt

Ryker She
Intellectual 2140 points
Part Number: DRV8849

Tool/software:

Hi Team,

Could we connect the pin STEP1 and STEP2 with same frequency signal?

Besides, do we have some suggestions to enhance MCU's GPIO frequency? Because customer uses low-end MCU and it is limited by PWM resource, they can only use GPIO which can only support 2kHz frequency but the suitable frequency of LDRV8849 is more than 8kHz. So do we have some suggestions to solve this issue? Thanks.

Best Regards,

Ryker

  • 0
    TI__Genius 9150 points

    Hi Ryker,

    Our device expert will look into this and get back to you.

    Thanks,

    Ibinu

  • 0 in reply to Ibinu Alaudeen Nadeera
    TI__Mastermind 33005 points

    Hello Ryker,

    Ryker She said:
    Could we connect the pin STEP1 and STEP2 with same frequency signal?

    This would mean you'd start and stop the two steppers at the same time as well as run at the same speed or a multiple based on the microstep mode selection. Electrically it should be fine sourcing STEP1 and STEP2 from the same input.

    Ryker She said:
    Besides, do we have some suggestions to enhance MCU's GPIO frequency? Because customer uses low-end MCU and it is limited by PWM resource, they can only use GPIO which can only support 2kHz frequency but the suitable frequency of LDRV8849 is more than 8kHz. So do we have some suggestions to solve this issue?

    If the MCU cannot generate > 2 kHz try using lower microsteps as much as possible. There is no way to overcome the MCU limitation. Alternately if you want a fixed frequency step input you can have a free running square wave oscillator generating STEP input which can be gated by an MCU gpio. This will not require any continuous bandwidth from the MCU. Example would be to use a single NAND Schmidt trigger such as the https://www.ti.com/lit/ds/symlink/sn74lvc1g132.pdf and use one input for gating and the other input to have an RC circuit for an oscillator. For driving two STEP inputs you could use a dual or two of these. 

    Regards, Murugavel