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DRV10987EVM: Technical Inquiry

Part Number: DRV10987EVM
Other Parts Discussed in Thread: DRV10987

Hello Team,

Good day. 

My Customer is using the DRV10987EVM to test the driver with a motor. They have been able to successfully drive the motor without errors. But it takes around 3 seconds from commands is sent to driver before the motor actually starts spinning. When it starts spinning it quickly goes into closed loop and works fine. But why this long delay before it starts doing anything? How fast should they expect it to take. What can be done about it?

Also: We can not find out how to control Direction over I2C. Any ideas or technical documents we can share?

Regards,

Renan

  • Hello Renan,

    Thanks for your question!

    The DRV10987 is a sensorless BLDC driver, and so it needs to go through a few steps before the motor can start. Initial speed detection determines if the motor is already spinning and then an align or IPD (initial position detect) is used to determine the starting point of rotation. Both of these procedures take time, however these times are adjustable over the I2C.

    Can you send over the register settings for us to look at? We may be able to offer some advice to reduce the start-up time.

    I do not see a way to control the direction of the motor over I2C, only based on the DIR pin.

    Thanks,

    Matt

  • Hi Renan,

    Thanks for posting your question in MD forum. DRV10987 is a sensorless BLDC motor driver so it needs to go through a start up sequence before it starts spinning the motor. We can make changes in the register settings to minimize the delay. Do we have the register settings from the customer? 

    We can minimize the delay by minimizing the time taken to align the rotor (if align is chosen as startup method) or decreasing the IPD clock frequency(if IPD is chosen as startup method). 

    In the past we have seen such startup delays when ISD is enabled. Can you check with the customer to see if the problem continues after disabling ISD? In addition, can you also ask them to check spdCmdBuffer[7:0] (address 0x06) to see if it is reading a non-zero value when the motor isn't spinning?

     Regards,

    Vishnu.