DRV8434: DRV8434 Stepping motor sensorless detection

Hello Wang,

Thank you for posting in this forum. 

wang sky said:

1. In the datasheet, it is mentioned that this IC uses sensorless to detect stall, when stall occurs, which pin is used to let the MCU know that stall occurs?

The DRV8434A and DRV8434S variants of this device has stall detection feature. This application note describes its working principle, https://www.ti.com/lit/an/slvaei3/slvaei3.pdf. When stall is detected it is reported on the nFAULT pin (LOW = stall). In SPI variant the DRV8434S it is also reported in SPI status register bit field. 

wang sky said:

2.DRV8434 is using sensorless to do motor position detection, does DRV8434 use that pin to send the motor position signal back to MCU, or is the detected motor position only known to DRV8434? If only the DRV8434 knows the motor position, how does the MCU know if the stepper motor has reached the reference position?

It does not send the motor position information to the MCU. The MCU should keep track of the end position (Stall detected) similar to using a microswitch in a 3D printer. The stepper driver does not have any feature to know the reference position or skipped steps etc. The MCU needs to take care of all of this based on stall (end of travel) in the application. Thank you.

Regards, Murugavel 

Thank Murugavel