DRV8889-Q1: How to Drive Unipolar Stepper Motors

Hello 

I refer to this E2E post and would like to ask if other models besides DRV8889 can be used but can achieve micro-step

Hi,

For 5-wire type only full-step must be used. It is not a driver limitation. It is a limitation of how the motor windings are wired in 5-wire unipolar motor and while using it with a bipolar stepper driver.

You could use use half-bridge driver, for example DRV8904-Q1 and use it as a low-side driver connecting the four wires to each output and the common 5-th wire to VM. You can generate your own indexer sequence to support half-step mode. Please refer to page-7 section 3.3 Driving Unipolar Motor with Four-channel Half-Bridge Driver of the application note https://www.ti.com/lit/an/sloa312/sloa312.pdf. 

The DRV8904-Q1 support only enabling bridges via SPI so this will limit the maximum step rate that can be achieved based on the SPI clock speed used and the microcontroller throughput. But it is usable. Thanks.

Regards, Murugavel