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DRV8889-Q1: Motor is moving, but CNTRL7 register with torque counter is always 0x00

Art Mecina
Genius 16655 points
Part Number: DRV8889-Q1

Hello Guys,

Good day.

Our customer made standard scheme with DRV8889A. He connected a motor from a car idle rev regulator. The motor is moving properly, but register CTRL7 with TRQ_COUNT is always 0x00 after the motor starts to move. At power on it is 0xFF.

Customer registers:
FAULT: 0x00
DIAG1: 0x00
DIAG2: 0x00
CTRL1: 0x00
CTRL2: 0x0F
CTRL3: 0x00
CTRL4: 0x30
CTRL5: 0x18
CTRL6: 0x0F
CTRL7: 0x00
CTRL8: 0x03

Motor is connected to DRV8889A in such way:
D = BOUT1
C = BOUT2
B = AOUT1
A = AOUT2

Thanks and regards,

Art

  • 0
    TI__Guru 56650 points

    Hello, Art,

    The TRQ_COUNT is related to motor speed (back EMF); output current and resistance.

    It could be zero if the motor speed is low and output IxR is high. If the output resistance is higher than 10ohm, we may not see a good result.

    Please check https://www.ti.com/lit/an/slvaei3/slvaei3.pdf to get more detail.

    Right now, the microstepping setting is the full step mode. Would you change it to 1/16 or 1/32 microstepping setting.

    Regards,

    Wang Li