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DRV8823: Cascading of DRV8823 using SPI

Padmanabh Gawai67
Prodigy 20 points
Part Number: DRV8823

I want to drive 8 Bi-Polar stepper motors , so planning to use DRV8823 so I can use single SPI Bus to drive 8 motors.

Wanted to know how shall we drive the following pins (SSTB, RESETn,SLEEPn,VREF)of each controller to reduce the driving MCU Pin count.

Has anybody used DRV 8823 in such an configuration

  • 0
    TI__Guru** 114905 points
    Hi Padmanabh,

    All RESETn and nSLEEP can connected together and controlled by a single MCU pin.

    Assuming the full scale currents of all motors are the same, all VREF can be connected together using a voltage divider.

    SSTB should be connected individually and held low until the data is to be transferred from the temporary holding register. When ready to transfer the data, strobe the SSTB pin of the desired DRV8823 high then low.
  • 0 in reply to Rick Duncan
    Prodigy 20 points

    Hello Rick,

    Thank you for responding.

    Do I need to have separate Chip select(SCS) pin for each driver chip ,OR can I use a common MCU pin and it will be High only when I want to have serial communication. Later the Strobe Pin of the specific Driver will be high to latch the data. I am assuming the specific motor output will be Enabled after the data is latched.

    RESETn,SLEEPn can also be toggled on an single MCU output for all 4 chips, so it will be active LOW to disable the Output of all drivers,when not in use.

    Let me know the preferred way to have good control over all 8 motors using 4 DRV8823 driver chips. Out of 8 motors we will be operating 2 OR 3  motors at a time.

    Padmanabh 

  • 0 in reply to Padmanabh Gawai67
    TI__Guru** 114905 points
    Hi Padmanabh,


    Do I need to have separate Chip select(SCS) pin for each driver chip ,OR can I use a common MCU pin and it will be High only when I want to have serial communication. Later the Strobe Pin of the specific Driver will be high to latch the data. I am assuming the specific motor output will be Enabled after the data is latched.

    >>> You do not need a separate SCS pin, but you do need a separate SSTB. Once the SSTB transfers the data from the temporary register to the motor command register, the device will begin operation.

    RESETn,SLEEPn can also be toggled on an single MCU output for all 4 chips, so it will be active LOW to disable the Output of all drivers,when not in use.

    >>> The connection will work as long as you want all devices to enter sleep and reset at the same time. If you want to set one device in sleep or reset only, the RESETn and SLEEPn pins will have to be separated.

    Let me know the preferred way to have good control over all 8 motors using 4 DRV8823 driver chips. Out of 8 motors we will be operating 2 OR 3 motors at a time.

    >>> If you can, separate the motors that will be enable to a separate DRV8823 to minimize the heat in the device. Example: Motor 1 and Motor 2 will always run together. Connecting them to DRV8823 1 will create twice as much heat in the device as connecting Motor 1 to DRV8823 1 and Motor 2 to DRV8823 2.