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DRV8711 - Functionality

Jagdish Gundu
Intellectual 390 points
Other Parts Discussed in Thread: DRV8711

Hello

This is Jagdish, I would like get some technical support on DRV8711, I have below following technical questions can you please confirm its functionality..

 a)            When I connect 2 dc motors on DRV8711, can we control direction of each motor independently [ can motor1 be CW and motor2 be CCW] and simultaneously

b)            When I connect one stepper motor, in case of fault.. do I get all fault information in SPI registers?

c)            Can we control the current in dc motor load or stepper motor load

d)            Do we need to give SPI command every time for every one step advancement in stepper motor application

 Can you please answer them ?

Jagdish

  • 0
    TI__Guru** 114905 points

    Hi Jagdish,

     a)            When I connect 2 dc motors on DRV8711, can we control direction of each motor independently [ can motor1 be CW and motor2 be CCW] and simultaneously

    Yes, each motor can be controlled independently. See question c) for more information on current control of DC motors.

    b)            When I connect one stepper motor, in case of fault.. do I get all fault information in SPI registers?

    Yes, all fault information is available in the SPI registers.

    c)            Can we control the current in dc motor load or stepper motor load

    Yes for the stepper. For DC motor, the current setting is the same for both motors. There is only one torque DAC. It is possible to use a different sense resistor to control the motor current.

    d)            Do we need to give SPI command every time for every one step advancement in stepper motor application

    No, there are two methods to advance. One is the SPI RSTEP bit. The second is pin 10 of the DRV8711 (STEP/AIN1). This input can be controlled by a PWM signal to advance through the indexer table. 

  • 0 in reply to Rick Duncan
    Intellectual 390 points
    Thank Rick,

    Can you please help me in understanding more on SPI. If suppose i need to move 200 steps on stepper motor application, do i need to load SPI data register and just enable CS PIN for movement or do i need to load 200 times SPI data register and control CS pin 200 times for its movement.

    I am asking this question because i hope you understand term baby sitting [meaning continuous follow up ], i dont want load MCU by having so many times of SPI communication. I am having other critical application like temperature readings on SPI bus.

    Is there any command in the register were configure saying move 200 steps and by enabling CS pin once the chip automatically moves 200 steps and stops.

    Thanks.
    Jagdish gundu
  • 0 in reply to Jagdish Gundu
    TI__Guru** 114905 points
    Hi Jagdish,

    The external STEP/AIN1 pin is available to minimize SPI communication. If you want to move 200 steps, the most efficient method is pulsing the the STEP/AIN1 pin 200 times. This pin is independent of the SPI, allowing the SPI to be used for other processes.

    The DRV8711 requires the SPI to initially set the registers and enable the outputs. After the initial settings, the SPI is used to monitor faults and disable the outputs, and in some cases lower the torque when the stepper is stopped.