I recently came across some stepper drivers i was unframiliar with, and as such decided to do some digging.
Here is an article someone made while trsting out these drivers. It seems the S6609 is a clone of the TMC 2209. Not too suprising with its name, but interesting to see how someone flushed out how to use/test a different driver.
Tldr the guy was looking for a cheaper/available tmc 5160 driver and gave the S6609 a try which turns out to be a cheap 2209 knockoff.