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DRV8705S-Q1EVM: Drive development issue

Part Number: DRV8705S-Q1EVM

Hi team,

The hardware drives brushed DC to the H-bridge, and the customer would like to know if there is a development timing for SPI similar to DRV8750s-Q1? For example, the timing of initialization, the timing of normal operation, the timing of diagnostics, etc.?

Also, do PWM waves for both IN1 and in2 inputs require complementary waveforms? Does HIZ1 and HIZ2 need to be pull high or low?

Could you please help check this case? Thanks.

Best Regards,

Cherry

  • Hi Cherry,

    The hardware drives brushed DC to the H-bridge, and the customer would like to know if there is a development timing for SPI similar to DRV8750s-Q1

    I'm not sure what you're question here is. Can you clarify please?

    Also, do PWM waves for both IN1 and in2 inputs require complementary waveforms?

    No. It's not required. Below is the control logic for the PWM control interface

  • Hi Pablo,

    I'm not sure what you're question here is. Can you clarify please?

    With both IN1/EN and IN2/EN being PWM inputs, how to configure the device via SPI to enable the drv8705 output to drive the motor and also can adjust the speed of the motor?

    Also IDRVP_HS, IDRVN_HS, IDRVP_LS, IDRVN_LS, VGS_TDRV, VGS_TDEAD, VDS_DG, VDS_IDRVN, VGS_LVL, VDS_HS_LVL, VDS_LS_LVL, PVDD_OV_DG, PVDD_OV_LVL, VCP_UV_LVL, CSA_BLK, CSA_GAIN, how should these values be configured, is there a problem configuring them to the default?

    Initialize the configuration of the drv8705-related register so that it operates in H-bridge PWM control mode and dynamically changes the frequency of the PWM as the motor is driven to complete the regulation of the motor speed according to the specific requirements. However, in the document, INx/EN simply inputs high or low levels, as can be seen from the chip pin description of the drv8705, GHx, GLx are outputs. But in H-bridge PWM control mode, a level setting is required, will they be paradox? SH1,SH2 is an analogue input, but in the H-bridge PWM control mode, it is also level control, and it is felt that there is a problem with the setting anyway.

    So now, after configuring the drv8705 register via SPI communication, they need a specific configuration timing that can control the motor's forward and reverse rotation while also being able to speed it by entering the PWM pins IN1/EN, and IN2/EN.

    And the following figure is the circuit diagrams, please help check is there anything wrong?

    Thanks and Best Regards,

    Cherry

  • Cherry,

    I guess they made the schematic with option for "H" and for "S" version?  That is why they have resistor divider and SPI connections?  

    For "S" version, speed and direction are controlled with PWM inputs under the DEFAULT spi configuration.  It is possible to controlled the outputs with the SPI version using register writes, but I would not suggest this if customer needs SPEED control.  For simple direction change without speed control, SPI can be used.  

    The defaults should be OK, but they must ENABLE the driver with a SPI command.  

    Regards,

    Ryan

  • Hi Cherry,

    I have not heard anything back from you in quite some time. I will close this thread for now. Reply back to this thread or ask a new related question if you require further assistance from us.

  • Hello Pablo and Ryan,

    Thanks for your support!

    This issue has been resolved by the customer after checking the drive principle. I believe we could close this thread for now. Thanks again!

    Best Regards,

    Cherry