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Original question:

DRV8899-Q1: operation without SPI

DRV8899-Q1: Without SPI

Jayden Qiu
Intellectual 1405 points
Part Number: DRV8899-Q1
Other Parts Discussed in Thread: DRV8889-Q1,

Hi Team,

This is FAE Jayden. I find the e2e question about the SPI as below. My customer also has some question about it. 

They only used DIR and step to control without SPI communication.  But there is not output on AOUT and BOUT. Can this work?

Brs

Jayden

  • 0
    TI__Genius 15355 points

    Hi Jayden,

    Jayden Qiu said:
    But there is not output on AOUT and BOUT

    When connected to an oscilloscope there is no output for AOUT and BOUT?

    Is the customer using DRV8899-Q1 or DRV8889-Q1?

    It is possible to use DRV8899-Q1 and DRV8889-Q1 without SPI control but that means you would have to operate with the default settings. The default settings can be found in the register map on the datasheet. Another thing to note would be that there is no way to detect STALL on DRV8889-Q1 without SPI communication.

    Regards,

    Yara

  • 0 in reply to Yara Al Shami
    TI__Intellectual 1405 points

    Hi Yara,

    You can get the device name on above pictures. They're using DRV8889-Q1. Does the code in above picture go well? The motor can't rotate in this condition.

    Brs

    Jayden 

  • 0 in reply to Jayden Qiu
    TI__Genius 15355 points

    Hi Jayden,

    Can you have the customer try to set DRVOFF=LOW and NSLEEP=HIGH when DIR=HIGH. It looks like DRVOFF=LOW and NSLEEP=HIGH only when DIR=LOW. The device will remain in sleep mode if NSLEEP=LOW and DIR=HIGH

    Regards,

    Yara

  • 0 in reply to Yara Al Shami
    TI__Intellectual 1405 points

    Of Course. I will let them try this. Thanks.

    Br

    Jayden

  • 0 in reply to Jayden Qiu
    TI__Intellectual 1405 points

    Hi Yara，

    They change the code and it doesn't work as usual. Noted that they use DRV8889A-Q1. Here attached the code they used and the CPL/CPH waveforms they have tested. Hope this help. If you need more waveforms. Pls let me know. Thanks.

     

    CPL waveform:

    CPH waveform:

    Brs

    Jayden

  • 0 in reply to Jayden Qiu
    TI__Genius 15355 points

    Hi Jayden,

    1.

    From the schematic you posted earlier, it looks like your customer is using DRV8889A-Q1 NOT DRV8889-Q1. DRV8889A-Q1 by default has DIS_OUT set to '1' and in order to change this you must use SPI communication and write "0" to this register.

    If your customer does not want to use SPI communication they can simply switch to DRV8889-Q1 where DIS_OUT by default is '0'

    2. 

    Another note on the schematic. the capacitors used from VM to VCP and CPH to CPL are not the values recommended in the datasheet

    this may not be the root of the current issue but may cause issues later. The values should be the listed recommended values or at least a 10:1 ratio meaning the capacitor value of VM to VCP should be tens times greater than the value of the capacitor from CPH to CPL.

    Regards,

    Yara